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For Dealer Sales Personnel

Cat Mining Trucks785C, 789C, 793D, 797B

September 2006

Caterpillar Product Information

Competitive Bulletin

Cat Mining Trucks 785C, 789C, 793D, 797B September 20062

Table of Contents

Machine Positioning Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Structures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Drive Train . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Mechanical Versus Electric Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Caterpillar Brake System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Steering and Suspension System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Hydraulics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Operators Station. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Monitoring System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

System Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Truck Bodies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Manufacturing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Product Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Technical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

September 2006 Cat Mining Trucks 785C, 789C, 793D, 797B 3

Machine Positioning Strategy

Caterpillar undertakes extensive field research to ensure customer needs are understood. High on the listof mining customer priorities are:

Lower cost-per-ton

Lower risk due to machine performance and operator safety

Less capital tied up in assets

Fewer liabilities

Caterpillar has responded with: research and development; continuous product improvement; superiorsupport, including MARC Contracts and Power-by-the-Hour; and tools such as Mine EIA (EquipmentInvestment Analysis).Today, as miners seek to reduce cost-per-ton, manufacturers are pushed to increase the payload capacityof haul trucks. New tire, electronic and engine technologies have been developed to deliver a more powerful,yet fuel efficient and environmentally friendly range of trucks. Caterpillar entered the ultra-truck marketwith the introduction of the largest mechanical drive mining truck in the world, the 797.


Competitive Situation

Caterpillar clearly leads the Mining Truck market with over 5,780 mining trucks shipped since 1985.Today, of every ten mining trucks sold worldwide, more than half bear the Cat brand. The remainingsales are shared between four major competitors:

Komatsu

Liebherr

Terex-Unit Rig

Euclid-Hitachi

The Caterpillar global dealership network is comprised of 182 Dealers with 59 in the United States and123 outside the U.S. Caterpillar dealers worldwide provide an unsurpassed level of personalized customerservice through more than 3,492 facilities (defined as main stores 182, branch stores 1,741 and rentalstores 1,569) in 182 countries.There are 135 Caterpillar manufacturing centers worldwide with around 57 located in the U.S. and 78 locatedoutside the U.S. With 14 remanufacturing centers, 12 technical centers, 4 proving grounds and 16 trainingcenters, Caterpillar applies more resources than any of its competitors to developing, testing and producinginnovative, high quality products that are supported by the best quality technical and service personnel inthe industry.

The Caterpillar parts distribution network features 22 distribution centers in eleven countries with 11 locatedin the United States. No matter where in the world customers are located, a Caterpillar dealer is within reachand has the most replacement parts in stock. On rare instances when a part is not found at the local level,the ANTARESSM Parts Order System can locate it in seconds. A dedicated Emergency Floor handles rushrequests and is on call 24 hours a day, seven days a week. Many Emergency orders are routinely shippedin less than four hours. This level of support differentiates Caterpillar from all the competitors and addstangible value to the Cat product.

Field PopulationHighest Hour Unit(As of June 2006)Total Units Fleet Hours

785 2,300+ 71 million 127,000789 1,800+ 67 million 106,000793 1,900+ 70 million 105,400797 190+ 3.9 million 49,000


Competitive Situation Caterpillar

Caterpillar offers a range of mining truck models in the 136 to 363 tonne (150 to 400 ton) size class.Caterpillars trucks are all mechanical drive with Caterpillars 797B being the largest mechanical drivetruck in the world. The Cat mining truck line-up includes:

785C: 136+ tonne (150+ ton) mechanical drive 789C: 176+ tonne (195+ ton) mechanical drive 793D: 218+ tonne (240+ ton) mechanical drive 797B: 345+ tonne (380+ ton) mechanical drive

The 793D is available in four different normal altitude configurations and one arrangement for high altitudeoperations. All configurations include key components matched to performance requirements in specificapplications and conditions:

Standard (MA1) for balanced all-around performance Extra Retarding (MA2) for long, downhill-loaded hauls Extra Top Speed (MA3) for long, flat hauls Extended Life Wheel Groups (MA4) for long, uphill hauls High Altitude Arrangement (MA5) for operations above 2750 m (9,000 ft)

Target Payload Capacity* (91-363 Metric Tonne Size Class)

(100-400 Short Ton Size Class)

EH3000 EH3500 EH4500-2 EH5000

785C 789C 797B

HD 1500 730E 830E

MT3000 MT3600B MT3700B MT4400

T252 T262 T282B

91 100

100 110

109 120

136 150

127 140

118 130

172 190

181 200

163 180

154 170

145 160

227 250

218 240

209 230

200 220

191 210

272 300

263 290

254 280

245 270

236 260

318 350

308 340

299 330

290 320

281 310

372 410

363 400

354 390

345 380

336 370

327 360

KOMATSU

LIEBHERR

CATERPILLAR

TEREX/UNIT RIG

EUCLID/HITACHI

* Approved weights as of 2005.

Note: Caterpillar models represent recommended target payloads for both standard body and MSD body configurations.

Competitors may approve higher payloads than indicated by using lighter weight bodies.

793D

830E - AC

930E-3

930E-3SE

MT3300

MT3300AC MT3700AC MT4400AC

MT5500B

MT5900AC

381420

Metric TonsShort Tons


Competitive Situation Komatsu

General Observations. Due to the strong mining market, Komatsu and other suppliers have reported recordsales and profits driven by the huge increase in demand for mining equipment. Komatsu is the principalmining machine competitor with a full-line of products.

Model Line-Up and Recent Introductions.

HD1550-5: 136 to 149 tonne (150- to 164-ton) mechanical drive 730E: 184 tonne (230-ton) DC electric drive 830E: 223 tonne (246-ton) DC electric drive 830E-AC: 221 tonne (244-ton) AC electric drive. 930E-3: 290 tonne (320-ton) AC electric drive. 930E-3SE: 290 tonne (320-ton) AC electric drive.

In 2004, Komatsu introduced the 930E-3 and 930E-3S in the 290 tonne (320-ton) class, which replacedthe 930E-2. The 930E-3, powered by the Cummins QSK60 engine, is rated at 2013 kW (2,700 hp), andthe 930E-3SE, powered by the Cummins QSK78 engine, is rated at 2610 kW (3,500 hp), which appearto be offered predominantly for high altitude applications in locations such as Chile.

Komatsu also introduced the 830E-AC in 2004 that among other features, is capable of speeds up to64 km/h (40 mph), an increase of 13 km/h (8 mph) versus the standard 830E DC that seems likely willcontinue in the market.

It appears Komatsu is promoting the 930E over the 830E, as the market in the 290 tonne (320 short-ton)class appears to offer more opportunities.



Product Issues and Known Problems. Feedback gathered indicated Komatsu has encountered the followingissues in the filed:

Komatsu trucks are bigger and heavier than Caterpillar trucks. With slightly higher GMW, Komatsutrucks have a significantly higher EMW, which translates into payload disadvantage. For example,several Cat 789C versus Komatsu 730E studies have shown at least 10-15 metric tons (11-17 tons)payload advantage for Cat 789C. A similar situation is found for the Komatsu 830E versus Cat 793C.

Additional weight represents tires and fuel consumption disadvantage. Mine records estimate that theaverage tire life on Komatsu 830E is at least 12 percent shorter compared to tires on Cat 793C. Also, fieldstudy data indicates the Cat 793C is in average 17 percent-20 percent more fuel efficient thanKomatsu 830E on a metric tons per liter basis.

Significant problems with Komatsu 730E DC wheel motor armatures when working in downhillhauling applications. Replacements were required with low operating hours.

Komatsu 730E are experiencing numerous disc brake pad failures due to excessive downhill speeds.

Successes and Selling Points.

Komatsu 930E is promoted as being a perfect three pass-match with cable shovels swinging 100 tonnes(110 short tons).

Selling downhill hauling speed and braking capabilities, leveraging AC drive system that providesignificant performance and safety improvements over the DC drive system.

Developing commercial alliances with mining companies with a long history of operating electricdrive trucks, such as Rio Tinto and Cleveland Cliffs, Codelco and Grupo Mexico.

Building a strong alliance with Cummins for the design and development of engines. The joint ventureagreement, effective in 1997, nominates Cummins as preferred engine supplier for Komatsu MiningEquipment.

Targeting emerging markets in India and Indonesia, at reduced prices with a global product.

Future Developments. Komatsu announced the development of the new 960E (327-345 tonnes[360-380 short tons]) and the new 860E (254 tonnes [280 short tons]). August 2006 Komatsu started thefield trial of 2 960E trucks. It has a 222 m3 (290 yd3) wider lower profile body and the truck has a ratedpayload of 327 tonnes (360 tons). One is running in the Canadian Oil Sands and the second is running inWyomings Powder river basin. It is rumored the truck is one year late from the proposed in the dirt datefrom Komatsu due to frame problems.

The 960E appears to have two different drive systems; for oil sands or hard rock mines.

The 960E has a 20 cylinder Cummins engine with 12 turbo chargers, and it is rated at 2759 kW (3,700 hp)but de-rated to 2535 kW (3,400 hp) in the oil sands. It has high torque Siemens AC drives. The truck shares930E elements and the same front end, but it is built slightly heavier. It has the same tire scuffing on theoutside fronts. The machine has bladder style steering accumulators that are very tall, and bladder changeis considered to be difficult.



Initial timing studies in the oil sands, de-rated 960E, indicate the 797B is significantly faster (10 percent)in High RR (> 9 percent).Speculation is high the company also is developing the 730E-AC.

It also announced the development of a new manufacturing facility in Japan for off-highway trucksscheduled for January 2007.

Five autonomous Komatsu trucks are being tested in Codelco, Chile.

Komatsu announced the co-development of hybrid drive systems with GE.


Competitive Situation Liebherr

General Observations. Liebherr has increased its participation rate and is indicating a strongdesire to compete. However, it appears Liebherr it is not willing to entertain high risk deals.

Model Line-Up and Recent Introductions.

T252: 181 tonne (200-ton) DC electric drive T262: 218 tonne (240-ton) DC electric drive T282B: 363 tonne (400-ton) AC electric drive

Liebherr offers three mining truck models, with the T282B being the largest size at 363 tonne (400 short-ton)capacity. Liebherr focuses heavily on the T282B and does not actively market the other machine models.

Product Issues and Known Problems. Limited manufacturing capacity (80-100 units per year)The T282B truck was successfully promoted as an ultra lightweight truck. However, it has many productproblems that tremendously affect its availability, and there is a big concern the lighter weight of the truckwill generate frame issues in the long term.

Unsuccessful introduction of its ultra light truck design concept, TI272, because of safety issues withrear tire changes.


A special sound attenuation package targeted in sound sensitive areas such as Hunted Valleyin Australia is a strong selling point.

It offers the best GMW/HP ratio in the industry.

Future Developments. Liebherr developed its own drive system, which will eventually integrate into the T282B.

There are speculations that Liebherr will reintroduce the TI-272 and also a second-generation machine,the TI-264, that will replace the current T262.


Competitive Situation Terex/Unit Rig

General Observations. After the collapse in failure of the negotiations with Caterpillar, Terex has reorganizedits Unit Rig and created more distance from O&K. Due to Terex reporting structure, it is difficult to establishUnit Rigs profitability contribution to Terex. It is however generally understood that Unit Rig contributionis probably under par and O&K sales carried the Mining dealerships.

Model Line-Up and Introductions.

MT3000: 109 tonne (120-ton) DC electric drive MT3300: 136 tonne (150-ton) DC electric drive MT3300 AC: 136 tonne (150-ton) AC electric drive MT3600B: 154 to 172 tonne (170- to 190-ton) DC electric drive MT3700B: 172 to 186 tonne (190- to 205-ton) DC electric drive MT3700 AC: 186 tonne (205-ton) AC electric drive MT4400: 218 to 236 tonne (240- to 260-ton) DC electric drive MT4400: 218 to 236 tonne (240- to 260-ton) DC electric drive MT4400 AC: 218 to 236 tonne (240- to 260-ton) AC electric drive MT5500B: 326 tonne (360-ton) AC electric drive

Since 2002, Terex has added three new AC drive trucks in its wide range of truck product offering,the MT3700AC (186 tonnes [205 tons]), the MT4400AC (up to 236 tonnes [260 tons]) and theMT5900AC (327-354 tonnes [360-390 tons]).Product Issues and Known Problems. Terex has limited manufacturing capacity.

The company lacks infrastructure for product support and is considered weak in many territories.

The General Atomic AC system on MT5500B has experienced serious problems, particularly wheel motorsoverspeed.

Field study data indicates Terex MT4400 AC (793 class) weighs much more than what is documentedin their publications, which affects tire and fuel consumption negatively.


Terex/Unit Rig is successful with Rio Tinto through the HME agreement.

North Hauler Lt. (NHL) is a joint venture with Terex for the manufacture and distribution in Chinaof 20-92 metric tons (22-101 tons) mechanic OHT and 154-340 metric tons (170-375 tons) electricOHT. Recently, the joint venture has been awarded an order for MT4400AC and MT5500B/MT5900AC trucks by a state-owned Chinese company for coal application.

Future Developments. Persistent rumors indicate Terex will exit the large off-highway truck business.


Competitive Situation Hitachi

General Observations. Hitachis focus appears to be in system selling, matching shovels to trucks.

Hitachi has decided to move large off-highway trucks manufacturing facilities to Japan away fromits traditional truck production facility in the U.S.

Model Line-Up and Introductions.

EH3000: 154 tonne (170-ton) DC electric drive EH3500: 172 to 181 tonne (190- to 200-ton) DC electric drive EH4500: 254 tonne (280-ton) AC electric drive EH5000: 284 tonne (312-ton) AC electric drive

Hitachi has four mining truck sizes. EH5000 is the largest with a nominal payload of 283 tonnes (312 tons).It also introduced the new EH4500-2, which provides a higher maximum gross machine weight than itspredecessor EH4500 in response to a nominal rated payload, not maximum.

In 2005, Siemens AC drive system was upgraded with EGBT technology only for EH4500 and EH5000.

Product Issues and Known Problems. Feedback gathered indicated Hitachi encountered the followingissues in the filed:

Very weak distribution, except for good Euclid dealers (Rudd, Colombia) Overheating of AC drive motors and frame cracking on EH4500

Weight distribution on EH4500 creates serious safety concern related to front tire overloadingand steering system operation.

In some sites, average availability of EH4500 is 15 percent lower than that of the Cat 793s.

Operators note rear axle tire spinning in wet conditions on EH4500.


Competitive Situation Hitachi


In downhill haul applications at high speed. The recent introduction of the Cat 793D MA2(Extra Retarding) has narrowed or eliminated the AC drive advantage in this application.

EH5000 and EH4500-2 are relatively strong products.

Selling shovel/truck system.

Future Developments. There are speculations the company is designing two new trucks, a 191 tonne-truck(210 ton-truck) and the largest of its range with a capacity of at least 363 tonnes (400 tons) that could bethe EH5500 or EX6000.


Other Competition: Truck Manufacturers

Belaz.

Belaz offers a range of rigid dump trucks from 30- to 220-tonnes (33-243 tons) capacity. Considering upsizing

Developing the first 320 tonne (354 short ton) capacity prototype with a 2610 kW (3,500 hp)Cummins engine and an electromechanical transmission.

Following is the 2006 line up of Belaz (all are equipped with a Cummins engine).7514 120 metric tonnes (132 short tons) 895 kW (1,200 hp)7513 130 metric tonnes (143 short tons) 1193 kW (1,600 hp)7530 220 metric tonnes (243 short tons) 1790 kW (2,400 hp)


Other Competition: Components

General Electric (GE).

Co-developed the OHT hybrid drive system with Komatsu.

Transitioning to IGBT technology in all AC systems in the future.

Market share of 92 percent, but OEMs moving away from GE.

Siemens.

Adding Komatsu to their OEM portfolio, along side Liebherr and Hitachi.

Speculations indicate they are working with Belaz on 354T truck.

Transitioning to IGBT technology in all AC systems in the future.

Active in less than 200T trolley systems.

Recently acquired Flender Gear for $1.4 billion.General Atomics.

Joint development with Terex on MT5500 and MT5900 models.

Cummins.

Tier 2 engines: QSK50 (1044-1566 kW [1,400-2,100 hp]) and QSK60 (1342-2237 kW [1,800-3,000 hp]). Tier 1 engine: QSK78 (2610 kW [3,500 hp]) is experiencing reliability problems.

Detroit Diesel.

Tier 2 engines: 12V4000 (1193-1678 kW [1,600-2,250 hp]), 16V4000 (1491-2237 kW [2,000-3,000 hp])and 20V4000 (2375-2796 kW [3,185-3,750 hp]).

Routinely demonstrating 24,000-hour life.

15

Caterpillar Truck Frames. Cat frames are builtfor strength and durability and incorporate thefollowing key features:

Finite Element Analysis. Proprietary computergenerated method of showing stress concentrationareas under load based on empirical data from actualtrucks. Castings are used for added strength anddurability in these high stress locations.

Controlled Weld Quality. Weld quality is strictlycontrolled. All welders are trained and certified.The use of rollover fixtures ensures all welding isdone horizontal not overhead. All critical weldsare 100 percent ultrasonically tested to findsubsurface defects. All defective welds areimmediately repaired and then rechecked.

Mild Steel Construction. The high strength lowalloy (mild) steel used in Caterpillar OHTs offerssuperior fatigue resistance and outstandingweldability characteristics. The weakest link in anyframe is in the welds. For that reason Caterpillarhas designed the frame using mild steel because ofits ability to produce the strongest welds. In additionlarge castings are used to move the welds away fromthe high stress areas. Mild steel is easily repairedin the field with standard welding techniques andequipment.

No Horse Collar. Easy in-frame engine accessallows quick repairs with less downtime.

Integral ROPS Cab. Frame is designed for anintegral ROPS cab and provides increased strengthin the front frame supports. Durable design providesadded operator protection.

Caterpillar Castings. Caterpillar uses castingsbecause of their proven strength and capacity toproduce design flexibility. Castings eliminate theneed for a lot of high quality welding that isexpensive and hard to achieve consistently. Withmore than 50 percent of the mining truck market,Caterpillar is the only truck manufacturer that canachieve economies of scale needed to make castingsaffordable. For competitors, castings are lessaffordable due to lower volumes.

Caterpillar integral ROPS cab frame.

Caterpillar truck frame with castings shown in red.

September 2006 Cat Mining Trucks 785C, 789C, 793D, 797B

Structures

Structures. Caterpillar main frames are the backbone of the mining trucks durability.

16

Integral Four-Post ROPS Cab. Resiliently mountedto the main frame to reduce vibration and sound,the integral ROPS is designed as an extension ofthe truck frame. The structure provides five-sidedprotection for the operator and is ROPS- andFOPS-certified to ISO standards. Caterpillar haschosen to meet the toughest standards and then gobeyond test certification requirements. Caterpillarcabs are designed to offer maximum operatorprotection in the event of a rollover accident.

Competitive Designs. Although the competitionpromotes their use of relatively high yield strengthparent plate in their structures with implicationsthat this provides lighter weight and longer life,catastrophic field failures at multiple sites haveproven otherwise. In fact, their structuresseriously compromise field supportability.

High yield strength provides increased resistanceto gross plastic deformation and fatigue strengthof the parent material. However, it does not improvefatigue life of full-scale welded structures, because:

Increasing yield strength comes at the expenseof toughness and results in increased sensitivityto inherent notches at the weld joints.

Localized plastic deformation, which occurs atthese notches, is much more damaging to highyield strength steels due to reduced toughness.

Crack propagation rates are much higher,rendering in-field service inspection and repairvery difficult. As a result, the structures becomemuch more prone to catastrophic failures.

Caterpillar Field Testing. Caterpillar and itscustomers learned of this trade-off throughextensive field experience and testing.

The full scale fatigue testing conducted byCaterpillar was corroborated by laboratorytesting of welded specimens by the BritishWelding Institute.

An optimum balance of yield and toughnessneeds to be maintained. Caterpillars weldjoints reflect this balance of yield strengthand maximized toughness.

In field applications, toughness and ability tolocally deform plastically provides a significantbenefit in case of accidents involvingextraordinary strains. Events that can be absorbedthrough plastic deformation rather than crackinitiation are less likely to result in subsequentfractures.

Rolled section steel in frame rails allows J-groove welds for better penetration.

Castings transition weld location to areasof lower stress.

While these mechanisms have their limits,Caterpillar Mining Trucks are much betterconfigured for tolerance of abnormal eventsthan competitors.

Caterpillar Integral Four-Post ROPS Cab.


Structures

17

Caterpillar Frame Design Versus Competition.Cat frames are backed by years of design experienceusing same design philosophy since 1963, resultingin a superior structure. Caterpillar has control overquality by manufacturing its own frames.

Frames are designed using the latest static anddynamic analysis techniques.

Frame design incorporates the loads anddeflections required by the integral ROPS cab.

Front superstructure eliminates the need fora horse collar, providing superior engineaccess and increased front frame strength.

Castings are used in areas of high stress.

Weld joints are located in areas of lower stress.

Mild steel provides a balance of medium yieldstrength and high toughness for:

Ease of welding. No pre-heat or post-heat.

Impact resistance.

Slow crack propagation.

Ease of weld repair, if required.

Long life.

High quality control during manufacturing.

Critical welds are 100 percent ultrasonicallytested for weld integrity.

Komatsu Frame Design.

Fabricated horse collar surrounds engine,increasing repair and service time.

930E is an upgraded 830E frame with thickermain rail plates with an unoptimized modulus.

930E uses 4921 kg/cm2 (70,000 psi) yieldstrength plate material and difficult to weldrepair 6328 kg/cm2 (90,000 psi) casting material.

Terex/Unit Rig Frame Design.

All fabricated. No castings used. More vulnerableto cracking failures.

797B frame. Extensive use of castings andnew weld technology results in longer life.


Structures

18

Euclid/Hitachi Frame Design.

All fabricated. No castings used. More vulnerableto cracking failures.

No consistent frame design among variousmodels.

Material yield strength varies among models.Euclid/Hitachi EH4500-2 and EH5000 use3515 kg/cm2 (50,000 psi) yield strength material.Other models use 7031 kg/cm2 (100,000 psi)yield strength material, which is not easilyweld repairable.

Liebherr Frame Design.

Fabrication and welding in high stress areas,which is more vulnerable for cracking failures.

Nickel copper combination steel frame.

Minimal section high stress dumpbody interface.

Liebherr truck frame.Euclid/Hitachi truck frame.


Structures

19

Caterpillar Truck Engines. The Caterpillar 3500BSeries EUI engine design focuses on performance,reliability and durability. Parameters are establishedto maximize engine performance while protectingthe engine from damage and undue wear. Successof this philosophy is evidenced by the 3500sdominance of its market segment.

Caterpillar has shipped more than 105,000 unitsover the past 25 years.

High quality manufacturing of the 3500B Seriesengines is ensured by the Caterpillar Engine Centerin Lafayette, Indiana, an ISO9001 Certified Facility.

Cat 3500B Engine Enhancements. The improvementsto the Caterpillar 3500B engine, as compared toearlier 3500 Caterpillar engine models, includehigher injection pressure, electronically controlledfuel injection timing and duration, enhancedcombustion chamber design, improved air systemmanagement, and electronic engine protection andmonitoring. Design enhancements have met specificobjectives for reduced fuel consumption, increasedpower capability, transient response, smokelessoperation, and lower emissions.

Electronic Unit Injection (EUI). The Cat 3500B SeriesEngines feature an electronic governor withElectronic Unit Injection (EUI). The brain ofthe EUI system is the Electronic Control Module(ECM). The ECM performs much like a mechanicalgovernor, but has no moving parts. The ECM sendssignals to the injectors to regulate the fuel supplyto control engine speed and power.

Electronic Unit Injection eliminates complexhydraulic governor linkages resulting in fewermoving parts. That means EUI provides customerssignificant improvements in reliability and durability.

EUI offers the following advantages:

Reduced Exhaust Smoke. EUI reduces smoke byelectronically adjusting the fuel limits to maintaincorrect air/fuel ratio.

Reduced Emissions. EUI reduces gaseous andparticulates emissions. Through electronic injectiontiming control, deep crater piston design andincreased injection pressure, fuel burn is optimized.

793D HAA*789C 789C HAA 797B HAA*

Model 785C 785C HAA 793D 797BEngine 3512B 3516B 3516B HD 3524B HD**Configuration V-12 V-16 V-16 V-24Bore mm (in) 170 (6.7) 170 (6.7) 170 (6.7) 170 (6.7)Stroke mm (in) 190 (7.5) 190 (7.5) 215 (8.5) 215 (8.5)Displacement L (in3) 51.8 (3158) 69 (4211) 78 (4758) 117 (7146)

*Two Stage Turbo charging**3524 is a tandem unit with two 3512B HD engines.


Engine

Engine. Cat engines are built for power, reliability and maximum operating efficiency.

20

Improved Fuel Efficiency. The ECMs abilityto match injection timing and duration with thetransmissions demand and a host of other sensedparameters allows fuel to be optimized not onlyduring steady state operation but also during transientacceleration fuel consumption is maximized overthe entire engine operating range.

Fuel Consumption History. The ECM storesinformation on machine fuel consumption.This can be used as a management tool toensure maximum life to overhaul.

Diagnostics and Troubleshooting. EUI offers anew generation of diagnostic and troubleshootingfeatures. Advanced, easy-to-use diagnostic systemsprovide easy reference to vital machine informationand quick solutions if problems arise.

Automatic Altitude Compensation. Power isautomatically derated as altitude increases to helpprevent excessive combustion temperatures andsubsequent component damage. An on-boardatmospheric pressure sensor derates the engineat the optimal cutoff point for each model.

Cold Start Protection. When temperature dictates,the engine is automatically put into cold modeto protect it from unequal distribution of load atstart-up and to eliminate piston scuffing and seizure.If the parking brake is on and the transmission isin neutral, low idle speed will rise to 1,600 rpm andtiming will be retarded until the engine is warmedup or until the transmission is put in gear. If thetransmission is put into gear before the engine hasreached operating temperature, the engine reducesthe amount of injection advance upon acceleration,to provide continuing protection.

Air Filter Restriction Indicator. By calculatingpressure drop across the filter, restriction can bedetected and the engine automatically derates ifthe allowable limit is exceeded.

Injector Diagnostics. Using an electronic servicetool, each injector can be tested to determine whichinjector requires service without taking exhaust porttemperature readings or picking up a wrench.

Engine Design Limits. Caterpillar performanceengineers impose an exhaust temperature limit,because exceeding that limit negatively affects fuelburn to overhaul goals. Damage, including warpedor burnt exhaust valves and turbocharger damagewould result if temperatures were allowed to gettoo high.

Cat engineers also maintain peak cylinder pressure,turbo speed, and turbo surge limits to ensure thatthe engine will not only meet the performance goalsbut also meet the expected life to overhaul goals.With many years of experience in the miningindustry, Caterpillar has been able to establishphysical material limitations specifically fordemanding mining applications to achievemaximum engine life.

Long Engine Life. Caterpillar truck engines aredesigned to provide the highest customer value overthe life of the machine. The expense of unplanneddowntime has a tremendous impact on cost per ton.This reality has played an important role in makingdecisions on how to design and apply the 3500 Seriesengine. Thermal stress, pressure and vibrationstresses caused by high BMEP are major factorsin reducing engine life.


Engine

21September 2006 Cat Mining Trucks 785C, 789C, 793D, 797B

Engine

Brake Mean Effective Pressure (BMEP).Brake Mean Effective Pressure is a measure ofhow hard an engine is being worked for its givendisplacement. This calculated parameter, expressedin units of pressure, could be used to compareengines of greatly different displacements andapplications.

Caterpillar BMEP Versus Competition.Recognizing that BMEP is critical in determiningengine life, Caterpillar designs engines to run ata much lower BMEP than the competition.Although diesel engine technology is the sameacross the industry, Caterpillar consistentlyapplies engines with a lower BMEP.

BMEP figures for competitive engines are morecomparable with figures for standby powergenerators. Due to high early hour failure rates,some competitors have abandoned the use of highBMEP engines in mining trucks. Most of theavailable alternatives have substantially higherBMEP than Caterpillar, as clearly indicated onthe graphic.

To calculate Brake Mean Effective Pressure (BMEP):

number of crank rotations per cycle(2 stroke or 4 stroke)Rev/cycle =

P (Bhp) rev/cycle 396,000D (in3) N (rpm)=

BMEP(English)

P (kW) rev/cycle 60,000D (L3) N (rpm)=

BMEP(Metric)

Power rev/cycleDisplacement Speed

BMEP =

0

500

1000

1500

2000

2500

QSK7

8

Stan

dby E

PG

QSK6

0

MTU

DDC

793D

(351

6B H

D)79

7B (3

524B

HD)

777D

(350

8B)

785C

(351

2B)

789C

(351

6B)

D11R

(350

8B)

994F

(351

6B H

D)

Engine BMEP in Truck and Other Applications

BM

EP (k

Pa)

22

Cat High Displacement Engine. The physical limitsestablished by Cat performance engineers are notstatic limits. Caterpillar is always conducting researchto develop materials, manufacturing techniques anddesigns that allow increases in engine capability.One example of how this has benefited customersis the 3500 HD (High Displacement) program.Piston technology had improved to the point whereCaterpillar was confident that piston speed increasescould be put into production. An evaluation of the3500B showed an increased stroke was possible.Applying this change has greatly benefitedcustomers of the 793D and 797B. With increaseddisplacement, and superior injection timing control,engine temperatures and pressures dont need tobe as high to produce the same amount of power.The High Displacement 3500 engine optimizesfuel consumption for a more fuel-efficient engine.Customers in the field have experienced higher fuelefficiencies due to, among others, the machinesability to hold gears longer with the HighDisplacement engine.

High Displacement Versus Standard Stroke.A plot of fuel consumption versus engine speeddemonstrates one of the benefits of a highdisplacement versus standard stroke engine.

Engine Combustion. The 3500B engine offersworld-class fuel economy. The combustion systemon the 3500B engine has increased valve lift andimproved combustion efficiency when comparedto early 3500 series engines. The 3500B fuel systemproduces high injection pressures over shortinjection duration resulting in enhanced in-cylindercombustion and better fuel burn. Internal ironchanges that provide these results includemodifications to the camshaft, rocker arms, camshaftfollowers, push rods, rear gear train, and pistons.

As a result of camshaft changes, the 3500B enginehas increased valve lift for both the intake andexhaust valve. The new lobe design yields 13%more lift, allowing the combustion chamber to filland exhaust with greater efficiency and withoutcompromises for engine overspeed.

Design changes to the piston provide significantimprovements in combustion efficiency of theair/fuel mixture within the cylinder. The shape hasa deep bowl crown that reduces crevice volume andincreases air compression. This change results inimproved fuel efficiency and lower emissions.The piston uses a proven, two-piece highperformance design with an aluminumskirt and forged steel crown.

Engine Cooling. The Caterpillar cooling system isincorporated into the total design of the truck andconsists of two parts, which include the jacketcooling system and the Separate Circuit Aftercooler(SCAC) system. It is built for efficiency anddesigned to take up no more space than necessaryin order not to diminish payload capacity. Use ofseparate cooling circuits enables Caterpillar toachieve effective cooling without excessiveradiator size or horsepower loss.

The 797B and 793D cooling system employshydraulics rather than belt drive, allowing the useof a demand fan. The demand fan reduces parasiticlosses when cooling requirements are less thanmaximum.

BSFC Comparison 793D 3516B HD vs 793C 3516B SS

0%

2%

4%

6%

8%

1250 1350 1450 1550 1650 1750

Engine Speed (RPM)

Bra

ke S

peci

fic F

uel

Cons

umpt

ion

(Impr

ovem

ent)


Engine

793D 3516B HD fuel consumptionadvantage in the engine operating range

23

For most efficient combustion, highest densitycharge air (coolest air) is required in thecombustion chamber. The lower the aftercoolerwater temperature needs to be, the bigger theradiator required.

Competitors tend to need more cooling to achievethe same emissions as Caterpillar. Because theyneed cooler water, theyre not nearly as wellpositioned to meet emissions requirements.Some competitors already face difficulty meetingemissions requirements and customers need toascertain how these companies plan to deal withnew emissions standards.

Caterpillar has a single aftercooler, or a doublecooler, depending on the model.

Cat Electronics. Cat 3500B engine performance isoptimized by an integrated electronic control system.The electronics optimize the fuel injection timingto improve power characteristics and fuel economy.Overall, the 3500B and 3500B HD series enginesoffer 6 percent to 20 percent lower fuel consumptionthan competitors mechanical engines, and in mostcases identical to or better than competitorselectronic engines. It is important to note that oftencompetitors use a fuel consumption tolerance of5 percent tolerance compared with 3 percenton Caterpillar engines.

Electronic Control Module (ECM). The ECM usesindustry leading control algorithms (software) andhardware to ensure peak engine performance overthe entire operating range. The 3500B enginecontrols consist of an engine-mounted AdvancedDiesel Engine Management (ADEM) ECM. With the exception of the 797B, which has a mastercontrol and two slave units, the 3500 engines useonly one ECM. The ADEM control facilitatesintegration of the engine with other Caterpillarcontrols on board the truck. Electronic unit injectors,sensors and the ECM regulate and monitor theoperation and health of the engine.


Engine

24

The ECM consists of two components: the controlcomputer and the control software. The controlsoftware contains the operating maps defininghorsepower, torque curves, air/fuel ratio, injectiontiming and transmission shift information. The ECMcontrols the injectors using feedback from variousengine sensors. Based on this input, the ECMdetermines fuel injection timing and durationto use for optimum performance.

Fuel injection timing depends on engine speed, load,throttle and other sensor inputs. The speed/timingcalibration sensor signals the location of top deadcenter of each cylinder, enabling ECM to controltiming and length of injection to maximizeperformance. The ECM will deliver only enoughfuel to reach Caterpillars limit on exhausttemperature, turbo speed, peak cylinder pressure andother key factors in maintaining a healthy engine,which will reach its expected life and beyond.

The ECM controls the variable horsepower settingson the Cat 797B (3524B) engine, to improveproduction. By exchanging information over theCat Data Link, the ECM allows the engine toaccelerate up to 1,950 rpm when the transmissionis in 7th gear, achieving top speed of 64 km/h(40 mph). When in torque converter drive, theECM allows the engine to limit its speed and thetorque to the drive train to extend component life.These features yield an increase in production anda decrease in cost per ton.

Monitoring and Diagnosis. The ECM performstwo engine health related tasks. First, it monitorsengine parameters such as oil pressure, enginespeed, filter differential, and boost, and determinesif these parameters are consistent with acceptableengine limitations. If not, the ECM records anengine event and initiates an alarm, a derate or ashutdown depending on the severity of the problem.Recorded events, including the nature of the event,the number of occurrences and service hour offirst and last occurrences, can be reviewed andinvestigated via the Electronic Technician (ET)service tool.

Second, the 3500B engine ECM has the ability todiagnose itself, its electronic sensors, and wiring.Diagnostic codes are generated and stored inmemory, as active or non-active, to reflect currentand intermittent or repaired problems. The codesprovide event description, number of occurrences,hour of first and last occurrence and total hours.In the 3524B, the codes also indicate which enginehas a fault. Logged diagnostic codes are helpful introubleshooting and are accessed via the CaterpillarElectronic Technician (ET) service tool. To furtherenhance serviceability of the system, sensors usedto monitor the engine are consolidated with theVital Information Management Systems (VIMS)sensors to reduce redundancy and complexity.

Cat Data Link. The ECM is a critical component ofthe Caterpillar Integrated Power Train ManagementSystem. Information is shared between smartcomponents over the Cat Data Link, allowingonboard microprocessors to communicate witheach other and access stored information fortroubleshooting. Most competitive machines lacksuch an integrated control and monitoring system.

Caterpillar Electronic Technician (ET) Service toolis used to diagnose the Cat 3500B engine.


Engine

25

Electronics Integration Features. The Cat integratedcontrol and monitoring system offers the followingelectronic control features:

Engine Overspeed Protection. If the enginereaches 2,100 rpm, a warning horn and checkengine message will activate in the message centerof the VIMS. At 2,300 rpm the transmission willautomatically upshift one gear regardless of caneposition. If the transmission is in top gear, thetorque converter lock up will disengage.An overspeed upshift event will be logged inmemory. The Automatic Retarder Control (ARC)computer will automatically activate in an overspeedcondition to control engine speed to 2,180 rpm.

Acceleration Delay on Start Up. To reduce wearon lubricated components, engine acceleration isdisabled for two seconds after low idle has beenattained, on start-up only. This allows time for allmachine lubrication and cooling systems to achievepressure and flow before operating at higher speeds.An engine pre-lubrication attachment is availableto pre-pressurize oil galleries within the engineprior to cranking the engine during start-up.

Elevated Low Idle. In cold weather conditions,low idle is elevated to allow the engine to achieveoperating temperature quicker and maintaintemperature. Certain conditions must be met forelevated low idle to be enabled: transmission mustbe in neutral, parking brake set and engine coolanttemperature below 75 C (167 F). Standard lowidle is 700 rpm.

Cold Mode Start Capability. The ability to startand to perform is improved in cold weather byretarding timing when the engine is below operatingtemperature. Retarded timing reduces peak cylinderpressure and cylinder pressure rate. The engineoperates in cold mode when engine coolanttemperature is below 70 C (158 F). The ECMalso modifies the amount of advance on accelerationwhen in cold mode to further protect the engine.

Air Filter Restriction. An air filter restrictionindicator monitors the air intake system. When theair inlet restriction is too high, the system willactivate a warning and record the event in systemmemory. The system will automatically derate as airintake restriction increases. When restrictions reach660 mm (26 in) of water, fuel is limited 1 percent.For higher restriction, fuel is limited 2 percent per102 mm (4 in) of water up to a maximum of20 percent.

Altitude Compensation. When operating at highaltitudes, the system automatically derates powerby limiting fuel to prevent excessive exhaust gastemperatures and related damage. The ECM usesatmospheric pressure to determine the enginesaltitude. High Altitude Arrangements (HAA)are available and they use either additionaldisplacement or two stage turbocharging to getfull truck performance even at the highest minesites in the world.

Diagnostics. The ECM is compatible with theElectronic Technician (ET) service tool, andinterfaces with Electronic ProgrammableTransmission Control II (EPTC) and ARC viathe Cat Data Link. ET plugs into a connector portlocated on the fuse panel behind the operatorsseat. ET can retrieve and display boost pressure,fuel flow rate, engine rpm, logged diagnostics,logged engine events, overspeed events, air filterrestriction, oil pressure, overheating and other sensorinput. ET provides numerous service featuresincluding individual cylinder cut out, crank withoutinjection, and injector solenoid test. ET is theprimary troubleshooting tool for the 3500B engine.


Engine

26

Fuel Use Record. The ECM provides a cumulativerecord of fuel consumed. This record is accessiblevia ET and VIMS.

Multi-Point Pressure Sensing. The engine oilpressure alarm will be activated if pressure falls outof spec. Oil pressure is monitored as a function ofengine speed and the information is passed onto VIMS. If a condition falls outside of normaloperating parameters, the operator will be alertedto decrease the risk of piston scuffing and enginedamage.

Ether Starting Aid. The ECM automaticallycontrols ether injection by determining if etherstarting aid is necessary based on engine coolanttemperature. Automatic ether injection controlprevents the possibility of the operator damagingthe engine by using too much ether during enginestart-up.

Starter Protection. The starter is protected fromdamage in two ways. First, the control feature willnot allow starter engagement if the engine speed isabove 0 rpm. Second, the starter is disengaged bya solenoid after the engine speed reaches 300 rpm.This prevents the starter from remaining engagedif an operator continues to hold the key in the startposition after the engine has started.

Oil Renewal System (ORS). ORS is an optionalsystem, which increases machine availability andproductivity by extending oil change intervals andreducing oil disposal and labor costs. ORS metersand injects used engine oil from the crankcaseinto the engines return fuel line, within carefullycontrolled parameters. The ECM performs controlof the ORS. No additional electronic modulesare required.

Oil Degradation Versus Time.

Oil Degradation versus Time

0 1000 2000 3000 4000 5000

Hours

Oil

Degr

adat

ion

3500 Engine Oil

Supply

Engine ECM

Transfer Pump

ORS Electronic Metering

Valve

Diesel Fuel

Fuel Tank

Mixed Return

Engine 2u Fuel Filter

Engine Fuel System

(Injectors)

Oil Renewal System


Engine

27

Electrical Connections. To improve reliabilityand serviceability, over 80 percent of the electricalconnections used are Deutsch connectors. VIMSand ECM sensors were combined to reduceredundant sensors on the engine. Additionally, thewiring harness and clipping of the harness on theengine and within the engine compartment isdesigned to facilitate easier and faster engineremoval and installation.

Caterpillar Engine Design Versus Competition.Caterpillar has a very real advantage in being ableto design and develop a fully integrated engine andpower train control system.

The Lafayette engine group employs enginesoftware specialists to develop a system thatwill control specific parameters for optimalengine efficiency, reliability and durability.

Based on extensive experience using the controlsystem on engines in different applications,Caterpillar has the expertise to integrate engineand power train specifically for the requirementsof mining.

Through the Mining Truck Engineering Groupin Decatur, IL, Caterpillar ensures system designand manufacturing suppliers work together tooffer a fully integrated system.

Competitive Engine Design. Competitors arechallenged when it comes to system integrationbecause they join together with up to three differentcompanies, each with their own performancecriteria. Cat doesnt face these difficulties withintegration.

Typically the engine manufacturer develops softwareto control and protect the engine, but the truckmanufacturer and the customer may have differentoperating parameters in mind. To reach agreementis a compromise, not likely to be ideal for any ofthe three parties.

At Komatsu, for example, integration of threedifferent systems is required. Engine controlsystems from Cummins and GE must be integratedwith operating systems from Komatsu. All aredeveloped separately and with different performanceparameters. While GE might want the operatingsystem to protect the engine, Komatsu may wantthe system to operate differently to meet customerdemands.

Komatsu-Cummins Engine Design. In a jointventure with Komatsu, Cummins has formed a newcompany (Industrial Power Alliance (IPA), andadded the 2610 kW (3,500 hp) QSK78 (alternativelynamed the Komatsu SSDA18V170), to its range ofengines for mining trucks, which also includes theQSK45 and QSK60. The joint venture agreementnominates Cummins as exclusive engine supplierfor Komatsu Mining Equipment.

Cummins QSK78 Engine.

1. 12 Holset Turbos 2. Belt drive alternator 3. Jacket water pump 4. Coolant filters

1

3

2

4

5116

117

5. Centrifugal oil filtration system6. 3 electric starters7. Auto prelube


Engine

28

Reducing product development and manufacturingtime, while minimizing development capital, IPAsourced off-the-shelf components for the QSK78.In an unprecedented union, the design team hadto accommodate ideas from both Cummins andKomatsu engineers. On-going development, specificmanufacturing and operational requirements wereto be achieved in the shortest possible time.

Komatsu-Cummins Engine Performance.Although the negative impact of increasingpeak cylinder pressures and specific power wasacknowledged, the BMEP of the QSK78 is morethan a third higher than the Cat 3524B. QSK60and QSK78 ratings exceed MTU/DDC 4000, andare similar to ratings for Cat Standby GenSets.Based on information available, the predicted lifeof the QSK78 would be significantly less than thepublished 20,000 hours. To date, there appears tobe no site where a QSK78 engine can be foundoperating and reaching expected parameters.

The QSK78 has a peak torque of 13,770 Nm(10,156 lb-ft) at 1,500 rpm while the Cat 3524Bpeaks at 17,220 Nm (12,701 lb-ft) at 1,300 rpm.At 1,900 rpm rated speed, the QSK78 produces13,100 Nm (9,662 lb-ft) versus 14,444 Nm(10,653 lb-ft) at 1,750 rpm for the Cat 3524B,a torque rise of 5% versus 19% for the 3524B.

Performance curves show 2610 ekW (3,500 BHP) atrated 1,900 rpm and BSFC of less than 201 g/kW/h,looks good versus Cat BSFC of 211 g/kW/h, butthere is no indication of tolerances.

Komatsu-Cummins QSK Family. Cummins optedfor a mono-block construction with added stiffnessand chose the power cylinder components (head,piston, ring pack and liner) from the Komatsuinline SAA6D170 family, which fit, with someadjustments. QSK78 uses a one-piece nitridehardened iron piston design.

Components for the QSK60 were derived fromthe Komatsu SAA6D170 family, but the extendedcrank length and additional crank throws requiredmodification to the piston crank. Concerns aboutreliability of the front gear train resulted in designchanges to accommodate wider, high-contactratio gears.

Accommodating new performance criteria and theengineering philosophies of both Cummins andKomatsu required a clean sheet approach in manyareas, but longevity of the QSK78 is yet to be testedin field applications.

Cummins Quantum Engine wasthe basis of the QSK78 design.

1. 2 Intercoolers2. Belt fan drive3. Inter/Aftercooler pump

4. Balance tubes5. 6 Aftercoolers (3 per side)6. Fuel/water separators

1

2

3

4

5

6


Engine

29

The QSK60 is a 60 L (16 gal) (2 m3 [3,672 in3]),159 mm bore and 190 mm stroke (6.26 x 7.48 in)2013 kW (2,700 hp) engine. The engine can beconfigured with one or two stage aftercoolingand with serial or parallel turbochargers.Approximately 25% of QSK60 productionis placed in mining applications.

Terex/Unit Rig also uses the Cummins QSK60engine in its larger mining trucks while Hitachiuses Cummins engines in some of its smallermining trucks.

MTU/DDC Engine Design. In a joint effort by DDCand MTU, Series 4000 MTU/DDC engines weredeveloped to provide fuel economy, reduced servicetime and promise of a 20,000 hour life to overhaul(in most applications). Since their introduction in1999, attention has been required to address issueswith injector seals, high-pressure pump failures,cooling system performance, charge air intakesystem and, most recently, main bearings.MTU/DDC engines are used in Liebherr,Terex/Unit Rig and some Euclid models.

MTU/DDC Versus Cat. The MTU/DCC enginerequires a much colder SCAC temperature and stillhas higher cycle emissions than the Cat 3500 engine.The MTU pushes the turbochargers harder to getits performance and it requires a higher BMEPto get to its rating.

Durability of MTU/DDC 4000 in the 830E and930E has been reported to be less than expected.There is evidence that some MTU/DDC 4000engines were stripped out due to disappointmentwith performance and serviceability in miningapplications. By comparison, with the veryserviceable Cat 3500 series engine, theMTU engine presents some challenges:

Very high levels of liquid nitrogen are involved.

Flangeless couplings are more complicatedand time consuming to deal with.

In tests conducted by Caterpillar, at mid-load andat high speed, the MTU had better fuel consumption,but throughout the entire load range producedmuch more smoke than the Cat 3500 engines.The MTU had higher NOx limits and particulatesemission than the Cat engine. The Cat 3500 enginealso has a better NOx/BSFC trade-off than theMTU/DDC 4000.

The MTU/DDC 4000 engine was found to havesome advantages over Cat 3500 series engines:

Slightly better Brake Specific Fuel Consumption(BSFC) than the Cat 3500 engines.

More efficient two-pass aftercooler.

Low and high idle engine noise.

Caterpillar offers the following advantages overthe MTU/DDC engine:

Lower installation costs. MTU requires26 percent more SCAC flow. More stringentinlet and exhaust restriction requirements.

Better tested emissions capability.Higher injection pressure.

Slightly less engine noise at rated point.

Lower cost rebuild as cylinder head has betterreman potential and flush bottom deck ischeaper to refinish.

Less expensive pistons.

Longer engine life.


Engine

30

Caterpillar Planetary Powershift Transmission.

Proven Cat technology uses durable largediameter clutch packs. Clutches and controlsare designed to provide smooth, automaticshifting while limiting clutch energy inputto give long clutch life.

The Cat patented design for rotating clutchpressure seals minimize drag losses and makerotating clutches as reliable as stationary clutches.

Gears are made from bearing-quality steel toavoid inclusions that can cause tooth breakage.High Contact Ratio Helical transfer gearsdesigned by Cat to control sound and givelong life.

On the new 793D, the extra top speedarrangement provides an input transfergear with lower gear ratio.

Precise planet gear tooth profiles are achievedby CBN grinding after heat treat. This reducessound and provides exceptional bendingfatigue life.

Planet gear teeth also are designed andmanufactured with crown to ensure correctload distribution across the tooth face.

Cat planet shafts are stone polished.This provides superior resistance to frostingand pitting compared to more commoncenterless-grind finished shafts. They alsoare more likely to be reusable at rebuild.

Routine maintenance and most control repairscan be made in-chassis. Modular design allowsquick transmission removal. Electronic controlseliminate linkage adjustments and lessen thechance of mechanical failures.

At rebuild, bearings, seals, gaskets, seal ringsand thrust discs are expected to be replacedregardless of condition; other components,including clutch discs and gears, may beinspected and reused.

Modular design allows quick transmissionremoval. When the transmission must beexchanged, it can be done by two mechanicsin a half-shift or less.


Drive Train

Drive Train. Cat mechanical drive train delivers more power to the ground.

31

Caterpillar Transmission Design. Electronicallycontrolled planetary transmission features:

Smart shifting with no gear hunting.

Downshift inhibitor prevents engine overspeed.

Optimum performance with minimum wear.

6 and 7 speeds forward, 1 speed reverse.

Top speeds: 785C in F6 = 54.8 km/h (34.0 mph);789C in F6 = 52.6 km/h (32.7 mph); 793D inF6 = 54.3 km/h (33.7 mph); 797B in F7 = 67.6 km/h (42.0 mph)

35 percent ratio steps in all ranges.

Torque converter lockup in first gear withtorque converter drive in reverse and firstgear below 7.2 km/h (4.5 mph).

Low torque design with most reduction infinal drives.

Transmission mounted directly to differentialhousing.

Controlled throttle shifting reduces torquecreated by the engine during shifts for smoothclutch engagement and improved componentlife. Ability to select any gear with cane.

Programmable top gear limit with any gearfrom 4 to 7 as top limit.

Directional shift management automaticallyreduces engine throttle before shifting fromneutral, reverse to forward and forward toreverse to protect driveline components.No operator input change required.

Neutral coast prevention will not allow thetransmission to shift to neutral if the groundspeed is above 6.4 km/h (4.0 mph). It onlydown-shifts to the proper gear for thatground speed.

On-board alphanumeric diagnostic displayrecords intermittent and active faults.

On-board memory records shift histogramsand lock-up clutch engagements.


Drive Train

32

Caterpillar Final Drives. Transmission and finaldrive parts work together to put more power onthe ground. Cat final drives are designed to workas a system to withstand the forces of high torqueand impact loads. They are manufactured and testedfor precise fit and heat-treated to ensure durabilityand long life. They deliver superior performanceand are of such high quality that they can beremanufactured for a second life.

Spindle bearing journals are laser-hardened. The differential bearings utilize newly developed

steel for increased resistance to fatigue failures.

Forged and ground crowned gear teeth preventexcessive stress on mating teeth and ensurecorrect load distribution across the face.Pitting, scoring and breakage is reducedto extend component life.

Cat mining trucks are equipped with a one-piececast rear wheel to accommodate high-capacitywheel bearings.

Cat Duo-Cone seal mountings within thewheel station prevent brake hub wear andincrease service life.

Direct lubrication of differential bearings isprovided through use of ground driven gearpump on 785C and 789C or continuous,hydraulically driven gear pump on 793Dand 797B. The lubrication is filtered priorto being directed to the components.

A new hydraulically driven filtration system on793D and 797B provides cooler, cleaner oil andparasitic power loss management via a constantoil flow to the final drives for longercomponent life.

The VIMS Monitoring System monitors therear axle system to notify the operator of lowlubrication levels, high temperatures and lowlubrication flow caused by plugged filters.

Extended Power Train Life. Cat final drives, wheels,and differential are designed and built for longpower train life.

Final Drive Features.

Flat deck carrier improves the ability to castand assemble; planet loads are equalized.

Higher capacity planet bearings for improvedreliability.

Improved heat treatment with an exclusivefinish and higher precision.

Wheel Features.

Optimized structure. High casting quality, highyield strength steel, can be re-manufacturedand repaired.

Front wheel spindle is forged or cast with laserhardened journals.

Rear wheel splined brake to spindle connection;improved stress distribution.

Increased capacity wheel bearings for betterload distribution.

Sealing designed to minimize debrisaccumulation.


Drive Train

33

Differential Features.

Structure designed to maintain optimum gearand bearing alignment.

Optimized effective bearing spread.

Spider bearing sleeves eliminated; new spiderbearings eliminate cage wear.

Pressure lubrication.

Rear Axle Lube System.

Continuous driven lubrication pump on 793Dand 797B. Ground driven lubrication pumpon 785C and 789C.

Parasitic power loss management.

Power Train Reliability. Caterpillar builds the bestdrive train parts on the market and achieves thehighest availability in the industry. Backed byexcellent maintenance and repair options, the resultis maximum productivity and lower costs. Cat offerseffective drive train maintenance, includingPreventive Maintenance (PM) programs, OilAnalysis, Inspections, Training, Scheduling, andRecordkeeping, which result in fewer failures andless unexpected downtime. Operating costs decrease,as machine life and availability increase.

Caterpillar Rim to Wheel Mountings. To mount rimsto wheels, Caterpillar uses a flange type mountingwith sufficient quantity of torqued bolts toaccommodate both vertical loads and tractive loads.A single torquing of the bolts is sufficient to preventslip or loosening of the joint. If, in the unlikelyevent the rim were to slip, the multiple bolts act asdowels to stop any further slippage. For more than30 years, Caterpillar has successfully used theflange-type mounting system in off-highway trucks.

Cat Duo-Cone Seals. Since the introduction ofoil-cooled disc brakes on Caterpillar mining trucks,Cat Duo-Cone seals have been an integral part ofthe design. Duo-Cone seals were developed in thelate 1950s to provide a new type of seal to improvelubricant retention in hostile, abrasive and corrosiveenvironments where elastomeric shaft seals woreout quickly.

The design of a Caterpillar metal-faced sealcompensates for many manufacturing and operatingvariables. Two metal sealing rings float in position;two elastomeric toric rings exert uniform pressureto accurately position the metal rings and serve asthe static seal between the housing and the seal ring.The load rings also transmit the turning torque fromthe driven housing to the seal ring. Positive sealingcontact is provided, regardless of assembly tolerancebuild up, deflections or end play.Caterpillar wheel station with laser hardened journals.


Drive Train

34

Metal-faced seals feature:

Corrosion resistant seal rings.

Precision lapped, self-renewing seal surface.

Minimum face load variations.

Long life.

Good performance across a wide rangeof face loads.

Service Support. Cat dealers can restore systemperformance and get machines back to work fast,helping to evaluate repair indicators and determinethe lowest cost repair option. Dealer service isguaranteed, with professional service people whohave the training and technology to handle all levelsof repairs. Even in remote areas, Caterpillar dealershave access to the worldwide expertise and supportof Caterpillar. Cat dealers also offer an unmatchedExchange or Cat Remanufactured parts serviceproviding parts that carry a same as new partswarranty but cost far less than new.


Drive Train

35

Caterpillar Mechanical Drive. Caterpillar entered themining market with the introduction of the 77 tonnes(85-ton) 777 in 1975. Prior to the introduction ofthe 777, all trucks in the 77 tonnes (85-ton) classwere electric drive. No competitor had attempteda mechanical drive with a power shift transmissionin larger trucks. The mechanical drive 777 withpower shift transmission soon became the dominantleader in the 77-91 tonnes (85- to 100-ton) classconstruction/mining trucks. Because of the greaterefficiency, rimpull, gradeability and durability,mechanical drive quickly replaced the electricdrive in the 77-91 tonnes (85- to 100-ton) class.Today, no competitor offers an electric drivein the size classes below 91 tonnes (100 tons).

Caterpillar trucks are used in relatively moresevere applications than competitive DC drivetrucks, but with the advent of newer AC trucks,the application ranges are now more comparable.Caterpillar mechanical drive systems offer thefollowing benefits:

Efficiency... more power getting to the groundand thus more useful work done.

Reduced fuel cost per ton... less fuel burnedper ton of material moved.

Power Train Efficiency. Power train efficiencyquantifies how much of the engine power generatedgets to the ground to do the work... moving materialefficiently from point A to point B. Engine powerthat doesnt get to the ground is wasted.


Mechanical Versus Electric Drive

Mechanical Versus Electric Drive. Cat mechanical drive trucks are built for superior control in the mostsevere applications.

36

Mechanical Drive. The mechanical drive systemis more efficient than both the DC or AC electricdrive system. A comparison of efficiencies on atypical mine haul grade of 10 percent shows the793 to be about 8 percent more efficient than an830E. Under the same conditions, the 797 is about6 percent more efficient than a 930E.

As effective adverse grades increase, the electricdrive becomes less efficient while the mechanicaldrive has a relatively constant efficiency as adversegrades change. For example, the efficiency of the830E truck drops from 81 percent on a 5 percenteffective grade to 66 percent on a 15 percent grade.The efficiency of the 793 truck actually increasesslightly from 81 percent on the 5 percent grade to83 percent on a 15 percent grade.

Higher efficiency of the drive train system resultsin less fuel burned per ton of material moved, whichtranslates into lower cost per ton operating costs.



Gross Power Train Efficiency

100%

72.281.5DC

7983AC

85.488793D

86.788797B

12%Peak

Mechanical drive systems are the most efficient over a broad operating range

Effective Grade

Gro

ss P

ower

Tra

in E

ffici

ency

95%

90%

85%

80%

75%

70%

65%

60%

55%

50%

45%

40%

35%

30%30%25%20%15%10%5%0%

793D 797B

AC Drive DC Drive

37

Electric Drive. The efficiency losses in anelectric drive system are caused by losses inpower conversion.

For DC systems:

Engine power to alternating current.

Alternating current to direct current.

Direct current to mechanical motion at thewheel motor.

Additional accessory losses to support theelectric drive system.

For AC systems:

Engine power to alternating current.

Alternating current to direct current.

Direct current back to multiphase alternatingcurrent.

Alternating current to mechanical motionat the wheel motor.

Additional accessory losses to support theelectric drive system.

Because electric drive systems are less efficient,competitors with electric drives must increasegross engine power to have grade power equivalentto mechanical drive. For example, the 830E has1864 kW (2,500 gross horsepower) compared tothe 793D at 1801 kW (2,415 gross horsepower). Mechanical Drive Advantages.Miners acknowledges that mechanical drive trucksoffer the following advantages:

Broader application range, steeper grades,good performance in poor underfoot conditionsand superior performance in high rollingresistance in tar sands.

Few thermal limitations on grade. The insulationin the Electric Drive wheel motor breaks downunder high heat and load conditions experiencedover long periods of time.

No high voltage electric support required.

High voltage safety.

Potential to use mechanical drive in moresevere conditions.

Better controllability retarding and driving.



Gross Power Train Efficiency

72.281.5DC

7983AC

85.488793D

86.788797B

12%Peak

Mechanical drive systems are the most efficient over a broad operating range

Gro

ss P

ower

Tra

in E

ffici

ency

100%

95%

90%

85%

80%

75%

70%

65%

60%

55%

50%

45%

40%

35%

30%0 10 20 30 40 50

793D 797B

AC Drive DC Drive

Ground Speed-mph

38

High stall rimpull.

Environmental tolerance mechanical driveis less affected by wet conditions.

Lower fuel costs per ton.

Fewer electrical parts.

Electric Drive Advantages.

Less maintenance time is required to changeoil and filters.

Trolley compatibility.

Less oil volume.

Fewer gears and mechanical parts, althoughmechanical drive has no high voltage linesor control cabinets.

Faster downhill hauling speeds.

No wearing of brake parts during retarding,but mechanical systems have no blowersor heat rejection grids.

Electric Drive Disadvantages.

Efficiency.

Support multiple suppliers.

System integration multiple software systems.

Complex to trouble shoot.

Stall torque capability.

Thermal capacity.

High voltage lines and control cabinets.

Traction control.

Conclusion. Caterpillars field research concludedCat mechanical drive trucks have functionalcapabilities that promote their use in a broader rangeof applications than the DC and AC drive trucks.

Competitive DC trucks perform well in lightduty applications.

Competitive AC trucks have a wider rangeof applications than the DC drive trucks.

The 218 tonnes (240-ton) AC drive trucks werepreferred in severe downhill hauling until therecent introduction of the Cat 793D MA2 (ExtraRetarding), which has narrowed or eliminatedthe AC drive advantage in this application.

The responsiveness of power electronictraction control software in electric trucks isslightly inefficient when compared to the Catmechanical drive Traction Control System.

Some competitors market machines withlower prices for repair and maintenancecontracts falsely, creating the perception thatelectric drive is a lower cost-per-ton option.Maintenance costs and conditions needto be compared carefully.



39

Operating Cost Comparison. Miners acknowledgecost per hour (or ton) varies widely between minesites depending on a number of variables, andCaterpillars studies confirmed this variation is fargreater than the variation between mechanical andelectric drive systems. For mature systems operatingunder similar conditions, there is no significantdifference in operating costs for the electric vs.mechanical power transmission system in miningtrucks. The difference in drive type impacts ononly 16.5 percent of the total cost-per-ton.

Cost-per-hour of the total propulsion systemaveraged:

Engine: 46 percent

Power Transmission: 16.5 percent

Wheel Station: 37.5 percent

Product Support. Every element of Caterpillarsmechanical drive train is performance-matchedand built to take the abuse of haul truck applications.

From the heavy-duty design of the 3500 series engineto the six/seven speed transmission, through doublereduction planetary final drives and the all-wheel,oil-cooled disc brakes, each component in everysystem is designed for maximum durability.

The result is a mining truck that performs better,breaks down less and lasts longer. And just asimportant is an unmatched product support team Repair Before Failure programs, remanufacturedcomponents and reusable parts, Scheduled OilSampling, regular maintenance options,worldwide parts inventories and an extensiveparts distribution system.



40

Caterpillar Brake System. Caterpillar oil-cooledmultiple disc brakes for off-highway trucks have along development history. When Caterpillar begandevelopment of an off-highway truck in the late1950s, oil-cooled brakes were an integral part ofthe design. Improvement of the brake has been anon going process since those early days. For manyyears only Caterpillar offered the superior oil-cooledbraking system on off-highway trucks. Severalcompetitors have since tried to copy the Cat system,but have not kept up with the advances andinnovations offered by Caterpillar.

Integrated Design. The Caterpillar designed anddeveloped non-fade, oil-cooled braking system isan integral part of the overall truck design, not anadd-on or afterthought.

The integrated design serves four braking systems:

service

retarding

secondary

parking

The service and retarding functions are actuatedby modulated hydraulic pressure on the brake pistonthat in turn applies a load or force on the brake rotorsand stators. The secondary and parking functionsare actuated by multiple springs acting on thesecondary/parking piston. The springs are releasedby modulated hydraulic pressure. Hence, brakes arealways available even in the event of a completehydraulic failure very important safety feature.No other manufacturer has ever offered an oil-cooledbrake with the safety feature of spring applied/oilreleased secondary/parking brake.

1

1 Parking/Secondary Piston 2 Service/Retarding Piston 3 Friction Discs 4 Steel Plates 5 Actuating Springs 6 Cooling Oil In 7 Cooling Oil Out

2

7

65

4

3


Caterpillar Brake System

Caterpillar Brake System. Cat oil-cooled, multiple disc brakes offer exceptional, fade-resistant brakingand retarding for maximum performance and productivity in all haul road conditions. Integrated BrakingControl combines retarding and traction control into one system for optimum braking efficiency.

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Four-Wheel Braking. The large Cat trucks havefour-wheel braking for superior retarding controlwith wet haul road conditions. Single axle retardinglimits controllability during slippery road conditions.Operator security is much greater with the four-wheel brake system, resulting in greater productivity.Trucks with two-wheel or single axle retarding mustcease operations during conditions of slick haulroads while Cat trucks can continue to operate.

The parking brake is applied to all four wheelsto give superior parking capability. The parkingsystem provides parking capability on grades upto 15 percent with worn brakes at the targeted grossmachine weight. No competitor provides four-wheelparking brakes. Since the parking brake system alsois oil-cooled, inadvertent application while movingwill not burn-up the brakes, which is the casefor competitors.

Brake System Design. The Cat oil-cooled disc brakesystem delivers exceptional performance due tosuperior design features.

The large frictional area is determined by thegross machine weight to give low retardinghp/in2 and high wheel torque for shortstopping distances.

Front to rear brake torque split is balancedto give the best braking performance andto minimize wheel lock-up especiallywhen in the retarding mode.

The non-fade characteristic of oil-cooled brakesenables reduced stopping distances comparedto systems using either dry caliper disc or drumtype brakes. As trucks became larger, retardinggrades steeper and regulatory requirementsmore stringent, only the Cat trucks were ableto meet legal braking requirements withoutmodifications.

The friction material has been improved fromthe original sintered bronze to a cellulose fibermaterial. To be more environmentally friendly,asbestos ras eliminated from the friction materialin the 1980s. The friction material is continuallybeing modified to improve frictional, wear andheat resistance characteristics.

The energy absorbed by the brakes duringretarding is dissipated by high flow of oilthrough the discs and separator plates. The oilis cooled by water-to-oil heat exchangers togive good retarding capability.

Extended life friction material has double thewear life of standard brakes and is twice asresistant to glazing for more consistentbraking power with less noise.

Hydraulic Automatic Retarder Control (HARC).Hydraulically activated automatic retarder controlsystem electronically controls retarding on gradeto maintain optimum engine rpm and oil cooling.It is designed to modulate the brake system inorder to maintain a constant engine speed, andit also promotes smoother engagement, betterresponsiveness, loping removal, less air systemdemand and fewer air system parts. Additionalbraking may be applied using the manual retarderor the brake pedal. HARC is deactivated when theoperator applies the brake or accelerator controls.



42

HARC vs. ARC.

Less chance for engine overspeed

Smoother engagement

No loping

Less air system demand

Reduces operating costs

HARC Production Advantages.

Traction Control System (TCS). Caterpillar trucksalso use the rear oil-cooled brakes for tractioncontrol. The exclusive Caterpillar system improvesperformance in poor underfoot conditions byelectronically monitoring and controlling wheelslippage. Sensors monitor wheel speed and if thedifference exceeds a preset limit, the oil-cooledbrake is actuated on the faster spinning wheel.With a standard differential output, torque to thetwo wheels is always equal. Applying brake torqueto the faster spinning wheel (the one with leasttraction) will then give additional torque to theslower wheel and provide additional tractiveeffort. Normal steering maneuvers do notactuate the system.

Integrated Brake Control (IBC). The HARC andTCS are combined into an Integrated Brake Control(IBC) System to enhance Cat truck performanceand increase productivity.

Serviceability. Maintenance of the oil-cooledbrake is minimal since the brake is enclosed andsealed. Additionally, brake material wear conditioncan be determined without disassembly of the brake.By removal of a service plug and insertion of asimple service tool, wear of the disc pack is easilydetermined.

10Time (Seconds)

20 30 40 50 60

With Hydraulic Automatic Retarder Control(average speed, 1950 rpm)

With Manual Retarder Control(average speed, 1730 rpm)

Engi

ne S

peed

(rpm

)

700

2500

1500

1000

500

2000

1 2

4

3

5

8

6

6

7

7

TCSHARC 1 Service Brake Sensor 2 Engine Sensor 3 HARC 4 HARC Switch 5 Brakes 6 Service Brakes 7 Axle Speed Sensor 8 TCS



43

Regulations. All brake tests to determinecompliance with regulatory requirements are runwith the truck at the maximum allowable grossmachine weight and not at nominal gross machineweight as in the past. Seldom will the truck weightbe at the nominal because of variations in loadingtool fill factors, material density variations, andloading tool operator skill. It is imperative thenthat the truck has adequate brakes when loadedto the maximum allowable gross machine weight.

Caterpillar Brake System Versus Competition.The brake system on Caterpillar mining truckshas been designed for optimum braking efficiencyand safety.

Oil cooled multiple disc brakes provide non-fade braking and retarding on all four corners.

Braking force is applied in a ratio of 40 percentfront, 60 percent rear for better handling andcontrollability.

Automatic electronics control the retardingfunction.

Rear brakes provide traction aid.

Service and retarding brakes are hydraulicallyapplied for greater efficiency.

Secondary and parking brakes are spring appliedfor added safety.

The application of emergency brakes canbe modulated for a brief period before theyremain applied.

The brake system exceeds legal/regulatoryrequirements at maximum allowable grossmachine weight.

Completely sealed system is not affectedby environment, including water and dustcontaminants.

Brake wear measurement can be undertakenwithout disassembly.

Komatsu Brake System. The brake system features:

Hydraulically applied front and rear dry caliperdisc brakes are subject to dirt and moisture entry,which can cause premature wear and/ormalfunction.

Rear brake discs on the high-speed motorarmature develops high torque but very limiteddynamic capability. Small disc diameter of635 mm (25 in) provides limited frictional area.

Spring applied, hydraulically released parkingbrake on high speed motor armature developshigh torque but almost no dynamic capability.

Dynamic electric retarding through tractionmotors and grid system.

The 930E-3 and 930E-3SE brake system features:

Hydraulically applied front and rear brakes areoil cooled multi-disc brakes.

Retarding capability with the oil-cooled brakesis limited since oil flow is low.

Spring applied, hydraulically released parkingbrake on the high-speed motor armature developshigh torque but almost no dynamic capability.

Dynamic electric retarding through tractionmotors and grid system.

Terex/Unit Rig Brake System. The brake systemfeatures:

Hydraulically applied front and rear dry caliperdisc brakes are subject to dirt and moisture entrywhich can cause premature wear and/ormalfunction.

Rear brake discs on the high-speed motorarmature develop high torque but very limiteddynamic capability. Small disc diameter of508 mm (20.2 in) on the MT3000, 635 mm(25 in) on the MT4400 and 787 mm (31 in)on the MT5900 provides limited frictional area.



44

Spring applied, hydraulically released parkingbrake on high-speed motor armature developshigh torque but almost no dynamic capability.

Accumulators that require routine pressurechecks and maintenance provide secondarybrake power.

Service and secondary brakes share the samebrake circuit and are more complex. Circuitincludes: pump, shuttle valves, pressure reducingvalve, relief valves, accumulators, pilot-operatedcontrol valves, steering versus brakes priority.

Euclid/Hitachi Brake System. The brake systemon the Euclid/Hitachi EH3000 and EH3500 features:

Hydraulically applied front and rear dry caliperdisc brakes are subject to dirt and moisture entry,which can cause premature wear and/ormalfunction.

boletin competitivo camiones mineros caterpillar -tejb8063-01

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