gdw6115k chassis workshlp manual (gl6111gr2)

8/3/2019 GDW6115K Chassis Workshlp Manual (GL6111GR2)

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Operation and Maintenance

Manual for GL6111GR2 Bus

Chassis


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PREFACE

Dear customers, thank you for purchasing and using Guilin Daewoo buses.

Guilin Daewoo Co., Ltd. is situated in Guilin City-a world famous scenic resort. The advanced technologies

and production concepts introduced from South Korea Daewoo Co., Ltd. together with solid R & D andproduction strength as well as perfect quality assurance system and after-sale service system ensure that Guilin

Daewoo Co., Ltd can provide you with best quality products and service. For many years, Guilin Daewoo has

drawn the attentions of more and more clients by upholding the business philosophy of people first, customer

centered t.

This manual describes structures, methods of maintenance and parameters of major parts on chassis. If making

full use of this manual and strictly carrying out the principle service imperatively, inspect periodically, and

repair as appropriate, the technical personnel undertaking maintenance for products of Guilin DAEWOO Bus

Co., Ltd. can keep your vehicle under favorable technical conditions and extend service life of complete bus. To

use the nonstandard products may affect complete vehicle performance resulting in vehicle damage evenendangering driving safety, so we strongly recommend that you use the products appointed by us or of the

models in line with the original parts.

In order to provide better service for you, our company set up sales and service hotlines. In case of any doubt

during the use, please contact us in time, and we shall provide warm, sincere and timely service for you.

Address: #10, Jingping Rd., Xiangshan District, Guilin, Guangxi Zip: 541003

Sales Tel:0773-3626218 Fax:0773-3605961 Email: [email protected]

Aftersale service Tel: 0773-3626258 Fax:0773-3605579 Email: [email protected]

We will appreciate it very much for any valuable advice and suggestion you put forward during the use of this

operation and maintenance manual.

Thanks again for your choice of Guilin Daewoo Buses!

Guilin Daewoo Bus Co., Ltd

Oct. 2008


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DECLARATION

Dear customers, for the purpose of your more convenient repair and maintenance of your vehicle, we edit thisoperation manual for bus chassis. This manual is distributed free of charge by Guilin Daewoo Bus Co., Ltd. and

no entity or individual may hold back it. The vehicle owner should ask for this manual from the sales

department while purchasing a bus.

In case of repair and maintenance of chassis of this series buses, please use the Guilin Daewoos genuine spareparts or accessories recommended by Guilin Daewoo. The vehicle owner himself shall be responsible for any

vehicle damage and harmful consequence caused by using of unauthorized or poor-quality parts or components

and Guilin Daewoo will refuse to take any responsibility for it.

Because of continuous technical innovation, Guilin Daewoo Bus Co., Ltd. reserves the right to modify andrevise this table of manual without prior notice of the modified items, for which we request your understanding.

In case the data, illustration or explanatory text in this manual disagrees with the actual vehicle, the actual

vehicle will prevail. You shall under no circumstances use any data, illustration and explanatory text in thismanual as a legal basis to lodge any claim to Guilin Daewoo Bus Co., Ltd.


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Contents

Section I General Notices................................................................................................................................. 1

1. General Notices ......................................................................................................................................... 1

2. Vehicle identification............................................................................................................................... 2

3. Vehicle specifications ................................................................................................................................ 2

4. Lubrication ................................................................................................................................................ 5

Section II Clutch ............................................................................................................................................. 10

1. Overview ................................................................................................................................................. 10

2. Trouble diagnosis..................................................................................................................................... 10

Section III Transmission................................................................................................................................... 12

1. Structural features of transmission .......................................................................................................... 12

2. Technical data for QJ1506 transmission ................................................................................................ 13

3. Axonometric drawing of QJ1506 transmission ....................................................................................... 14

4. Application and maintenance for QJ1506 transmission .......................................................................... 15

5. Common fault and troubleshooting of QJ1506 transmission ................................................................ 17

6. Removal/Reassembly highlights of QJ1506 transmission....................................................................... 18

Section IV Driving shaft................................................................................................................................... 20

1. Overview ................................................................................................................................................. 20

2. Trouble diagnosis..................................................................................................................................... 22

Section V Front Axle ........................................................................................................................................ 22

1. Main specifications.................................................................................................................................. 22

2. Reference outline drawing ..................................................................................................................... 23

Section Rear Axle ........................................................................................................................................ 24

1. Main specifications ................................................................................................................................ 24

2. Reference outline drawing....................................................................................................................... 24

Section VII Steering System............................................................................................................................. 25

1. Overview ................................................................................................................................................. 25

2. Common faults and inspection method ................................................................................................... 26

Section VIII Suspensions (Air Springs) ........................................................................................................... 29


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1. Overview ................................................................................................................................................. 29

2. Specifications ........................................................................................................................................ 29

3. Front Air Suspension ............................................................................................................................... 30

4. Rear Air Suspension ................................................................................................................................ 31

5. Installation & adjustment ....................................................................................................................... 33

6. Use........................................................................................................................................................... 33

7. Service & maintenance............................................................................................................................ 34

8. Shock absorber ........................................................................................................................................ 35

9. Fault analysis & maintenance.................................................................................................................. 36

SectionWheel & Tire ..................................................................................................................................... 41

1. Overview ............................................................................................................................................... 41

2. Use & maintenance.................................................................................................................................. 44

3. Excessive wear of tire and its first cause ................................................................................................. 51

4. Installation, inspection & correction of tire............................................................................................. 51


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Section I General Notices

1. General Notices

When parking the vehicle, park it at a flat place for safety; also, put the hand brake intoaction and block front and rear wheels properly.

After axle or frame is jacked up, supportframe using frame supporting rack properly

before any maintenance operation.

Before starting a job, disconnect batteryground wire to avoid the accident caused by wiredamage and short circuit.

Cover such areas as body, seats and floorwith boots to prevent damage and contamination.

Oils and antifreeze coolant etc. can corrodevehicle paintwork, so take extra care and do notsplash them to other areas.

For the places having the prompts for use ofspecial or particular tools, use the tools to

improve maintenance efficiency and quality.

Use genuine automobile parts of DAEWOOCompany.

Discard used cotter pins, gaskets, O-rings, oilseals, spring washers and lock nuts etc. Neverreuse them, replace them with new ones.

Otherwise normal functions of correspondingparts can not be guaranteed.

To ensure smooth assembly operation forinstallation validity, keep the removed parts bytype and sort in order.

Store fastening bolts and nuts by category because they are different in material and

precision (also, their assembly positions are

different somewhat).

Before inspection and assembly, clean up allparts and components. At the same time, clean

oil passages using compressed air to ensure that

they are unobstructed.

For the surfaces between which relativerotation or slip exists, apply lubricant or greaseto them before assembly. When necessary, use

seal packing to prevent leakage.

Tighten all bolts and nuts to the specifiedtorques.

After finish of assembly, perform anotherthorough total inspection to ensure installationvalidity of all parts.

To ensure safety, when removing lines orother parts having pressure from a pressure

vessel, release pressure in air tank slowly first.

1


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2Vehicle identification2-1.Chassis number

Bus chassis name plate is fixed and VIN code is stamped at the rear area of right longitudinal beam of front

axle.

2-2. Engine Nameplate

As shown in the figure, the engines nameplate is located at the upper top of cylinder.

3. Vehicle specifications

3-1Main technical parameters of chassis1. Engine

Engine Nameplate


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Chassis model GL6111GR2

Model YC6L310-30 DL08

Type Inline six-cylinder, four-stroke, direct-injection turbocharged inter-cooled engine

Number of

cylinders6

Bore stroke

(mmmm)113140 108139

Displacement

(L)8.424 7.640

Air intake

methodTurbocharged inter-cooling Turbocharged inter-cooling

Rated

power/RPM(kW/r/min)

228/2200 250/2200

Maximum

torque /RPM

(N.m/r/min)

1150/1400 1323/1200

Minimum fuel

consumption at

full load

(g/kW.h)

210 197

Noise (ISO

3744)dB(A) 119 94

Emission (TAS) Euro

2. Clutch

Chassis model

ContentGL6111GR2

Type Single, dry coil spring; Single, dry diaphragm spring

Diameter of clutch disc (mm) 430

Clutch operating method Hydraulic-air powered

3. Transmission

Chassis Model

ContentGL6111GR2

Model S6-90 QJ1506

Type 6 gear, step speed change, mechanically controlled, air powered


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Gear ratio

I:6.37

II:3.71

III:2.22

IV:1.36

V:1

VI:0.74R:5.87

Volume of gear oil About 13(L)

4. Rear axle

Chassis Model

ContentGL6111GR2

TypeWith half-shaft sleeve casting/welding axle housing

Final drive Hyperbolic gear single reduction

Final drive ratio 3.909,3.545

Gear oil filling capacity (L) 12.5

Load capacity (kg) 13000

5. Front axle

Chassis Model

ContentGL6111GR2

Type Forged steel component, I-section, two-end Elliott type

Front wheel track (mm) 2084

Load capacity (kg) 5500

6. Steering system

Chassis Model

ContentGL6111GR2

Type of steering gear integral recirculating ball power steering gear

Diameter of steering wheel (mm) 500

Steering oil filling capacity (L) 11

7 Braking system

Chassis Model

ContentGL6111GR2

Type Dual-circuit air brake

Front 410Bore of brake drum (mm)Rear 410


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Front 16016 mm8Friction lining

WidthDepth (mm) Number

of linings Rear 22016 mm8

Type of parking brake Energy storage spring braking against rear wheels

Auxiliary braking system Retarder

8 Suspension

Chassis

ModelGL6111GR2

Suspension mode Air Suspension Leaf spring

Airbag Quantity Front: 2 & rear: 4

Steel plate Quantity 12 pcs for the front, 12 pcs for the rear

Stabilizer bar Front and rear stabilizer bars

Type Two-way acting telescopic hydraulic suspension shockShock absorber

Quantity Front: 2 & rear: 4 Front: 2 & rear: 2

Leveling valve Quantity Front: 1 & rear: 2

9Wheel and tyreChassis Model

ContentGL6111GR2

Dimension 11R22.5

Type Without inner tube

Tire

Inflation pressure (kg/cm2)

8.1 - 8.3

(This value is for reference only,please refer to the instructions

on the available tyre for the actual details)

Rim Dimension 22.58.25

Note: The above configurations shall be selected according to the specific

requirements when buying a vehicle.

4. Lubrication

4-1. Lubricant viscosity schematic

Engine oil


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Gear oil

4-2Lubricating positions and intervalsThe service life of bus components is mainly dependent on lubrication. Therefore, lubrication in correct way

duly to the whole vehicle during the use, service and maintenance is very important. Lubrication of whole

vehicle, please observe closely the following rules:

1. Remove the fouling on oil cap, oil plug or oil nozzle, etc. before lubricate some items to prevent fouling

from falling into the mechanism.

2. When replace the lubricating oil of all assemblies, operate under the hot engine state (but not allowed to

startup or run) to ensure that the waste oil and dirt can be freely drained.

3. When our bus leaves the factory, current engine, transmission, rear axle, steering gear and antifreeze will be

changed according to real production situation.

WARNING: It is prohibited to use oil of different brands or specifications.

Grade of precision of engine oil-ambient temperatureSingle-stage

Ambient tem erature

Multi-stage

Viscosity grade of gear oil -ambient temperatureSingle-stage

Ambient tem erature

Multi-stage


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4. During the season changing service in summer or winter, select the oil products of proper brands.

5. Before the bus leaves the factory, if it is installed automatic filling system of butter(C.L.S), its lubricant, use

and repair refer to relative documents provided by manufacturer.

6. Take care to reclaim lubrication oil. The reclaimed oil is stored according to different types respectively and

keep away from impurity. It shall be delivered to the reclaiming processing office to handle in the right way

and avoid pollution to environment.

Lubricating

place

Name of

oilChange period Capacity

Recommended

Specification and grade

Engine Engine oil

DOOSAN engine:

Bus, every 20,000km

Highway passenger

vehicle, every 30,000km

Engine-made in China:

Please refer to the

Operating & Service

Manual for Engine

YC6L310-30

About 24-28L

DL08

About 21-27L

CH-4

SAE 15W-40

CI-4

SAE 15W-40

Transmission Gear oil

Please refer to the

Operating & Service

Manual for Transmission

QJ1506 about 13L

S6-90 about 13L

API GL-4

SAE 80W

Rear axle Gear oil

First time: 2,000km or

after the vehicle reaches

the customer.After that: every

20,000km.

about 12.5L

API GL-5

SAE 80W90

Power steering

Power

steering

fluid

First time: 2,000km or

after the vehicle reaches

the customer.

After that: every 24,000

km.

About 11LDEXRON-D (Never

use hydraulic oil.)

Wheel hub

bearingGrease Every 8,000km Just enough Multi-purpose HP-R

Clutch Brake oil

Every 1 year or

60,000km.

(Please refer to the

Operating & Service

Manual for Transmission

for the details)

Appropriate

capacity is 1L

DOT-3 or DOT-4(Use of

mineral oil brake fluid is

forbidden.)

Note: The lubricating periods listed in the table are the recommended values only, and the regular check

must be done. In the different regions and under the various application conditions, the passenger vehicle

owners should determine the lubricating period according to the experience and reference to this table,

which focuses on the reference to the product operating & service manuals provided by the


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manufacturers of various assys and parts.

4-3. Layout of Cargo Loading System (C.L.S)

If the vehicle is equipped with the cargo loading system (refer to the Operating Manual of C.L.S for use and

maintenance), the layout of loading positions is as follows:


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Note: Apart from these loading positions above, the other loading positions are manual loading positions.

10mm

10mm

10mm

10mm

10mm

6mm

Nozzle

diameter

0.1

0.2

0.2

0.4

0.4

0.2

0.1

Oilvolume

BRAKE

CAM

SHAFT(RH)

BRAKE

ANCHOR

BRKTRR(RH)

SLACKADJUSTRR

(RH)

KINGPINUPR(RH)

KINGPINUPR(RH)

SLACKADJUSTRR

(RH)

BRAKE

ANCHOR

BRKT(RH)

Englishname

Chinesename

7 6 5 4 3 2 1 SN

10mm

10mm

10mm

10mm

10mm

10mm

10mm

Nozzle

diameter

0.2

0.1

0.1

0.1

0.1

0.1

0.2

Oil

volume

LINKARM

CLUTCHPEDAL

ACCELRELAYLEVER-SHAFT

ACCELRELAYLEVER-SHAFT

T/MRELEASELEVER-CLUTCH

T/MRELEASELEVER-CLUTCH

T/MRELEASEBEARING

Englishname

Chinesename

14

13

12

11

9 8 7 SN

10mm

10mm

10mm

10mm

10mm

10mm

6mm

Nozzle

diameter

0.1

0.2

0.2

0.4

0.4

0.2

0.1

Oilvolume

BRAKECAMSHAFT(LH)

BRAKEANCHORBRKTRR

(LH)

SLACKADJUSTRR(LH)

KINGPINUPR(LH)

KINGPINUPR(LH)

SLACK

ADJUSTER

FRT

(LH)

BRAKECAMSHAFT(LH)

Englishname

Chinesename

21

20

19

18

17

16

15

SN

10mm

Mainfuelpipe

KFU2-40fuelpumpsete

PSB1016universalhingedjointe


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Section II Clutch

1. Overview

1-1. Structure

The single plate dry type clutch installed on this modelof chassis plays the roles of engagement and

disengagement of power transmission between engineand transmission case. The clutch mainly consists of

compressing disc, driven disc, clutch cover, spring,release lever, etc. The driven disc locates between the

flywheel and the compressing disc and contacts between the both under the action of the spring thus

transferring torque of the engine to the transmissioncase through mutual friction force. The control

mechanism of the clutch is oil pressure controlled.When you depress the clutch pedal, the pedal force

will be transferred to the release yoke through themaster cylinder and the slave cylinder and then release

the compressing disc through the release sleeve andthe release lever thus allowing the driven disc to

release the interaction between the engine and thetransmission case. If you release the clutch pedal,the compressing disc will force the driven disc against

the flywheel under the action of the pressure spring

thus transferring power of the engine to thetransmission case again.(Please refer to the Operating Manual provided by theclutch manufacturer for the detailed maintenance

information)

1-2.Main specifications

Chassis Model GL6111GR2

Type Single, coil springSingle, dry diaphragm spring

Diameter of clutch disc (mm) 430

Clutch operating method Hydraulic-air powered

Friction plate outer diameter x inner

diameter x thickness

(mmmmmm)

4302403.5, 4302505

Material of friction plate Without asbestos

Pressing force (N) 24000, 22700(+1800-1362)

Release ring adjusting height (mm) 750.4, 830.4

2. Trouble diagnosis

2-1Clutch slip . When accelerating, acceleration of the vehicle can not keep up with that of the engine.. Engine overheat.

. Engine underpower.


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Cause Measure

1) Free travel of clutch pedal insufficient.

2) Oil or grease on driven disc.

3) Driven disc excessively worn.

4) Clutch spring broken or weakened.

5) Release sleeve deformed.

1) Adjust to its proper position according to the specified

value

2) Clean or replace driven disc.

3) Replace.

4) Replace.

5) Correct release sleeve or front shroud.

2Halfway clutch release . Hard shift

1) Free travel of clutch pedal too large.

2) Clutch oil leak.

3) Height of release lever uneven.

4) Wear of clutch parts uneven.

5) Air in clutch oil hydraulic circuit; stroke of

slave cylinder insufficient.

6) Axial motion of driven disc improper caused

by wear or seizure of driven disc and driven shaft

spline.

1) Adjust to its proper position according to the specified

value

2) Replace piston cup. Replace if piston and cylinder

sleeve are excessively worn.

3) Adjust.

4) Correct or replace driven disc, compressing disc,

flywheel, clutch spring, release lever support column, etc.

5) Bleed or repair slave cylinder assembly.

6) Clean spline and coat it with lubricant.

3Unsmooth clutch engagement . During engagement, clutch operates unsmoothly and trembles.1) Driven disc deformed or worn unevenly.

2) Compressing disc or flywheel worn unevenly.3) Damper sheet of driven disc broken or

damaged.

4) Rivet of driven disc damaged.

5) Buffer spring of driven disc aging or damaged.

6) Height of release lever incorrect.

7) Pressure spring aging or damaged.

1) Replace.

2) Correct or replace.3) Replace.

4) Replace.

5) Replace.

6) Replace.

7) Replace.

4Noise from clutch system . Regular noise is heard after clutch pedal is depressed.. Sound from clutch pedal arm.

1) Thrust bearing excessively worn or locked.

2) Clutch pedal shaft lubricated poorly.

1) Replace.

2) Fill grease.


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Section III Transmission

1. Structural features of transmission

Refer to the maintenance methods of QJ1506

transmission for the S6-90 transmission, or refer to

the related documents provided by the

manufacturer.

Structural features of QJ1506 transmission:

1-1. QJ1506 is a three-shaft type fixed shaft drive

transmission, with fix forward gears and one

reverse gear. The reverse gear uses the joint sleeve

to shift the gear, and all the forward gears use the

short stroke or twin cone lock ring synchronizer.

1-2. The gearshift mechanism uses the unique ZF

rotating shaft - pulling plate - fork type mechanism;

and it may equip with single rod and various kinds

of soft shaft mechanisms, with more simple andreliable gear shifting.

1-3. Unique self-locking and inter-locking devices. The

Neutral gear position of this transmission is located

between passageways of 4th/3rd gear, and all gear

positions share a self-locking mechanism which is


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used to self-lock all gearshift positions of the

transmission; and the advanced unique interlocking

device is used to interlock all gearshift plates, which

dont involve in gear shifting, so as to ensure that

simultaneous shifting to two gear positions of this

transmission doesnt occurs when gear shifting. Unique

self-locking and interlocking devices.

2Technical data for QJ1506 transmissionStandard Transmission Ratio

Type Input Torque

N.m1

stgear 2

ndgear 3

rdgear 4

thgear 5

thgear 6

thgear Reverse

Overdrive gear 1200 6.37 3.71 2.22 1.36 1.00 0.74 5.87

Odometer gear ratio1.545 (additionally install the secondary drive set according to the

owners demand)

Center

distance154mm

Gross weight Approx.225Kg

Dry box refilling

capacityHorizontal installation, 13.0 L


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3. Axonometricdrawing of QJ1506 transmission

3-1. Transmission case and clutch housing

assembly.

3-2. Front end cover, input shaft, intermediate

shaft, reverse gear shaft assembly.

3-3. Output shaft assembly.

3-4. Gearshift fork assembly

3-5. Transmission gearshift mechanism assembly.

3-6. Bracket assembly.

The synchronizer ring is made of steel materials, and

its friction surface is treated by using the

molybdennum spraying technology to improve the

service lifetime of the synchronizer. The gear drive

is fully or partially bevel gear drive. The form of

gear tooth is modified and the tooth root fillet is a

big round angle. The gear is made of (ZF special

gear steel products), and subject to the shot blasting

treatment after thermal stress; and the gear is

machined by using the gear grinding. The purpose of

these technologies above is to improve the strength

of gear and reduce the noise.


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4. Application and maintenance for QJ1506transmission

4-1. Operating Instructions

This transmission features compact structure, light

weight, small dimension, flexible operation, simple

gearshift, reliable application, and easy-to-maintain;

multiple variants, good adaptability of complete

vehicle; and high universality of parts and

components.

The proper use and maintenance of this transmission

may undoubtedly improve the dynamics, economy,

safety and reliability of the complete vehicle. For

this purpose, five ZF operation essentials are

recommended for you:

The higher gears are used ASAP when thevehicle is traveling so as to ensure that then engine

operating condition is within the economic speed

area.

The skip-shift (shift to the next gear)operation can be implemented when the vehicle

accelerates so as to make the best of the engine

power.

You should shift to higher gear position whenthe vehicle is travelling downhill so as to fully use

the engine for braking.

You should pay more attention to the roadconditions, employ the Neutral gear and make use of

the vehicles inertia to travel.

The emergency foot brake pedal or sharpacceleration shall not be frequently used unless it is

absolutely necessary.

Precautions for use of QJ1506 transmission:

Properly adjust the clutch so as to fully release it

and completely engage it.

DO NOT overload.

Avoid no initial maintenance of the vehicle.

Avoid not to warm up the engine on site after the

vehicle starts, and not to immediately drive the

vehicle when the water temperature doesnt reach the

startup temperature and the air pressure doesnt rise

up to the standard air pressure.

Avoid the gear shifting of high speed in low gear

or low speed in high gear, and irregular out of gear.

DO NOT impact the gearshift, and avoid forcible

pushing, pulling or beating the gearshift lever for

shifting the gear.

This transmissions Reverse/1st

gear adopts the

joint sleeve for shifting the gear, two feet shall step

on the clutch pedal for shifting the gear, and the

vehicle shall stop while shifting to Reverse gear.

DO NOT shift to the Neutral gear when going

down on a slope.

4-2. Maintenance

The maintenance includes the following contents:

Routine maintenance and periodic maintenance.

(1). Check the fixed coupling of transmission and the

condition of operating mechanism.

The vibration or violent ups and downs caused due

to the road condition while the vehicle is travelling

may results in the looseness of transmission and

clutch housings, frame, engine, supporting drive

shaft, and the couplings of output flange, and thus

the fastening shall be checked every 1200 1400 km

mileage.

During the transmission is in service, a series of

abnormal conditions may gradually occur due to the

wear and deformation of gear, shaft, bearing, and

ball head rocker arm of gearshift mechanism. Since

the operating mechanism is exposed to the exterior,

the lubricating effect is poor. And the moisture in the

oil may result in the corrosion. It may cause the wear

of ball head of rocker arm of the gearshift

mechanism, which may result in the improper or

difficult gear shifting.

(2) Sealing condition of transmission

Check the condition of oil seals at 1st

shaft end and

output shaft end; and check whether there is oil

stains at the external of housing and cover. The oil

seal and its lip will be gradually worn flat during use,

the tension of oil seal self-tightened spring reduces,


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the sealing function of oil seal decreases and thus the

oil leaks. The shortage of lubricant resulted due to

leakage may cause poor lubrication and rapid wear

of parts. It is recommended that the transmission oil

seal is replaced once every 20000km mileage.

(3) Breather plug

Since its installation position and sealing may easily

result in oil loam, it will block the breather plug.

Since the breather plug is blocked, the operation of

transmission will result in the increase of air pressure,

which may cause the oil leakage. It is recommended

that the breather plug is checked once per every

1000km mileage and the breather hole is dredged.

(4) Lubrication

ZF transmission has strict requirements on the

designation, quality and quantity of lubricant.

In consideration of the current actual level of

lubricant, it is recommended that the lubricants

conforming to the following conditions are available:

Classified by the viscosity: SAE80W gear oil

Classified by the application: API-GL4 or

MIL-L-2105 heavy-duty gear oil

(5) Level of lubricant

No lubricant is filled into the transmission when

leaves factory. A product nameplate is located on the

cover of gearshift mechanism of the transmission,

and on the nameplate indicates the approximate

lubricant capacity of the assembly. of 13L, and it is

slightly added to approx. 13.5L after the first

maintenance or overhaul. The lubricant refilled shall

be the same brand of lubricant only manufactured by

the same manufacturer.

(6). Lubricant level check

The vehicle stops on the level road, and there is a

lubricant level inspection hole screw plug (painted

with a red sign) at the side of transmission under the

vehicle, and the oil plug is unscrewed with a 17-19

double offset ring spanner. If the lubricant overflows

from this inspection hole or if the lubricant can beseen, it indicates that the level of lubricant is

appropriate. It is recommended that the level of

lubricant is checked once every 700km mileage for a

luxury long-distance bus.

(7) Lubricant change period

The first compulsory maintenance of lubricant

change shall be done after the new vehicle leaves

factory and travels 2000km or gets to the owners

place, and the metal particles and foreign materials,

which are ground off during the run-in period of the

new transmission, shall be removed.

Recommendation: After the first maintenance of a

luxury bus, change the lubricant once every

80000km mileage or 2000h.

During changing the lubricant, carefully remove the

metal objects and foreign materials adhered to the

magnetic core of drain plug.


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5. Common fault and troubleshooting of QJ1506 transmission

Transmission noise abnormal

Possible Cause Remedy

Parts inside the clutch damaged or the fastener

loosened

Check the moving parts of the clutch, and replace the

damaged parts or loose fastener

Universal joint severely worn or drive shaft

clearance big

Check the drive shaft and universal joint, replace the

damaged parts or adjust the fit clearance

Lubricant shortageCheck the level of lubricant, and refill it to the

specified level according to requirement

Bearing or gear damaged, worn Check or replace the damaged or worn parts

Fasteners loosened or relative moving parts

damaged

Check the loosened fastener, and replace the damaged

parts

Hard shift


Halfway clutch release Check the clutch pedal play and adjust it

Control link train (center steering arm, gearshift

lever, connecting plate, supporting rod) improperly

adjusted or worn

Check and adjust the link train or replace the damaged

parts

Synchronizer parts or joint sleeve parts damagedCheck and replace the damaged parts, repair and grind

the damaged parts

Out of gear


Control mechanism (control operating rod, etc)

assembly improper or severely worn, which may

result in not shifting to gear in place.

Check and adjust

No play after the gearshift lever shifts to the gear. Check and adjust

Self-locking parts failure (spring, self-locking pin,

self-locking block)Check and replace the damaged parts and worn parts

The soldered tooth severely worn Replace the damaged parts

Bearing or bearing hole severely worn Replace the damaged parts

The gearshift parts damaged, worn (gearshift plate,

tie rod, fork, slide bushing) Replace the damaged parts

Clearance improper Recheck and adjust the clearance


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Oil leakage


On the housing/cover has the loose air pore, crack or the

screw hole punched throughReplace or repair

Fastener loosened Check the loosened fasteners

Seals failure, broken (oil seal, gasket, washer) Replace the failed, damaged parts

The breather plug blocked, which result in the failure of

sealsReplace and clean

Oil temperature high

Hint: The normal operating oil temperature may reach 100, and even 130 for no more than 30 min. underthe harsh working condition.


Oil level overhigh Drain out the excessive lubricant

Oil quality deteriorated Replace the specified lubricant

Clearance excessively small (bearing, gear and relative

moving parts)Adjust it according to the specified value

The moving parts severely worn (bearing, gear, etc) Replace

6.Removal/Reassembly highlights of QJ1506 transmission

6-1Main adjusting clearance and dataAdjust the clearance Adjusted Value

Intermediate shaft adjusting clearance 0.15-0.20mm

Axial clearance of 1st

shaft bearing outer ring 0.0-0.10mm

Axial clearance of output shaft bearing outer ring 0.0-0.10mm

Axial clearance of Reverse Gear intermediate gear 0.2-0.6mm

Adjusting clearance of 5th

gear cone nave 0.6-0.9mm

Axial clearance of circlip for shaft 0.0-0.1mm

Clearance of input shaft bearing spilt ring -0.01-0.02mm

Limit of wear between synchronizer ring and cone nave 0.8mm

Clearance between gearshift fork and sliding sleeve 0.4-0.9mm

Axial clearance of 1st

gear, 2nd

gear and 3rd

gear of 2nd

shaft0.15-0.40mm

Axial clearance of 4th

gear, 5th

gear and 6th

gear of 2nd

shaft 0.15-0.50mm

Gearshift lever swing play 2-3mm


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6-2Main removal tools

6-3 Removal

Principle of removal: The removal of

transmission is from simple to complex, from the

external to the interior, and from the upper to the

lower, and the sub-assemblies are disassembled first,

and then the components are removed.

Sequence of removal:

1. Place the transmission vertically, and remove the

upper cover assembly.

2. Remove the gearshift fork mechanism.

3. Remove the output flange, rear cover, worm, and

2nd

shaft rear bearing.

4. Remove the front end cover and 1st

shaft

assembly.

5. Hoist and remove the 2nd

shaft assembly.

6. Remove the reverse gear shaft assembly.

7. Remove the intermediate shaft assembly.

6-4. Assembly

Principle of assembly: In general, the parts which

are removed first are assembled last, and those which

are removed last are assembled first; and the

sub-assemblies are assembled first, and those

sub-assemblies are then installed.

Sequence of assembly:

1. Assembly and installation of the intermediate shaft

assembly

2. Assembly and installation of the reverse gear shaft

assembly

3. Assembly and installation of the output shaft

assembly

4. Assembly and installation of the rear cover

assembly and output flange

5. Assembly and installation of the input shaft, front

end cover assembly

6. Assembly and installation of the gearshift fork

mechanism

7. Assembly and installation of the upper cover

assembly, testing and adjustment of the transmission,

and removal and assembly of the attached retarder

6-5. Testing and adjustment of transmission

performance

(1) Test item

Shift to any gear in turn, check whether any gear

can be simply put into and whether the rotation is

flexible.

Check whether the play of gearshift lever rotation

against any gear position conform to 2-3mm (swing

leftwards and rightwards).

Operate any gear after the transmission is placed

on bench or installed onto the vehicle, and check

whether there is abnormal noise while the

transmission is operating with any gear.

Operate any gear after the transmission is placed

on bench or installed onto the vehicle, and check

whether there is out of gear.

(2) Adjustment method

Upper cover adjustment play method: Since there

is a certain clearance between the upper cover bolt

and screw hole, the upper cover can be slightly

moved leftwards and rightwards, and thus this may

adjust the gearshift movement of two relative gear

positions.

Link train adjustment play method: Adjust the

uniformity of any gear by adjusting the link train

upper supporting rod, ball head, control link train

and etc, and thus ensure the appropriate gearshift

lever play.


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Heating Temperature and Tightening Torque of Main Parts

M12 bolt 60Nm

Intermediate shaft gear

160 - 180 (remove

and assemble it with a

press of 60T or above ) M14 bolt 135Nm

5th gear bearing race 100 - 120 Turbocharger for the reverse gear is 60Nm

Synchronizer tooth holder 85 - 100 Gearshift fork anchor pin 220Nm

Bearing 85 - 100Transmission case upper plug screw

M16*1.530Nm

M8 bolt 25Nm Clutch housing bolt M18*1.5 270Nm

M10 bolt 49Nm Inner threaded plug screw M24*1.5 50Nm

Section IV Driving shaft

1. Overview

1-1. Structure

The universal drive system transmits the torque of

an engine to the rear axle. The drive system

together with the engine is installed onto the frame,

and the rear axle supports the frame through

spring. As a result of the function of suspension

spring and the vibration and deformation of frame,the relative position of drive system and rear axle

always changes.

Therefore, to adapt to the change of relative

position and relative angle of engine a rear axle,

the universal drive shaft consists of the spline

shaft, sliding sleeve and universal joint. The

universal joint generally consists of the spider,

needle bearing, oil seal and etc. Any drive shaft ismade of hollow shaft which can bear the bending

moment and torque.

Please refer to the Operating Manual provided by the drive shaft manufacturer for the detailed

maintenance information.


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Exploded view(for reference only)

1.universal joint fork 6. Grease nipple

2. Cross axle assembly 7. Hexagon head bolt

3. Needle bearing 8. Hexagon head nut

4. Snap ring 9.Spring washer

5.universal joint fork


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2. Trouble diagnosis

Universal drive shaft and vehicle body vibration

Cause Measure

1) Shaft fork not assembled properly

2) Drive shaft bent or deformed

3) Drive shaft parts loosened or bolts loosened

1) Adjust all parts of shaft fork

2) Replace or correct

3) Replace or correct

Abnormal operating noise from universal drive shaft

Cause Measure

1) Spline excessively worn

2) Spider or needle bearing worn, deformed or

damaged

3) Various components assembled loosened

4) Various components lubricated badly

5) Intermediate bearing worn or damaged

1) Check the axial clearance, and replace the worn

parts

2) Replace

3) Repair

4) Refill the butter for lubricating

5) Replace

Section V Front Axle

1. Main specifications

Item Parameter Item Parameter

Rated axle load 5500kg Toe-in 02mm

Maximum steering angleInner wheel 47; outer wheel

36Rim applicable 22.58.25

Tire bolt 10-M221.5 Brake structure type S cam bowl type

Diameter of wheel rim

distribution circle335mm Brake structure specification 410160mm

Kingpin inclination 7.5


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2. Reference outline drawing

Please refer to the Users Manual provided by the front axle manufacturer for the detailed

related information.


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Section Rear Axle1. Main specifications

Item Parameter Item Parameter

Rated axle load 13000kg Wheel track 1860mm

Tyre rim/ Tyre specification 22.58.25 Final drive ratio 3.9093.545

Tire bolt 10-M221.5 Diameter of wheel rim distribution circle 335mm

2. Reference outline drawing

Please refer to the Users Manual provided by the rear axle manufacturer for the detailedrelated information.


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Section VII Steering System

1. Overview

The steering system mainly consists of the steering

wheel, steering shaft, universal joint fork (yoke),

universal joint, spline shaft, steering column,

steering gear, steering rocker arm, steering linkageassembly and etc.

It is an integral power boost type steering gear, and

its steering screw connects with the steering wheel

through the universal joint fork, universal joint and

steering shaft. When turning the steering wheel, this

kind of rotary motion drives the rotation of screw of

the power steering gear, and the rotary motion of

the screw converts to the sliding movement of nut

via the circulating ball. The teeth on the steel ball

nut engage with the teeth on the sector shaft

connected with the steering rocker arm. So, with thesteering rocker arm, the rotary motion of the

steering wheel is tied to the movement of other

steering control levers.

The power boost type steering system automatically

provides the mechanical steering gear with the

hydraulic steering force. This power steering

system mainly consists of the control valve, powercylinder, power steering pump and etc. With the

function of control valve, the power cylinder

moves. Which direction the power cylinder moves

to fully depends on the position of the valve.

Regardless of the type of valve, i.e., whether it is a

rotor valve or slide valve, it directly connects to the

steering gear assembly. The pressure oil, which is

used to drive the operation of this system, is

provided by the vane-type steering pump.

Please refer to the Operating Manual provided by the steering system manufacturer for the relatedmaintenance information.

1-1Main specificationsChassis Model

Item

GL6111GR2

Type of steering gear Integral recirculating ball type power boosting steering gear

Type of control valve Rotary valve type

Diameter of steering wheel 500mm

Steering oil filling capacity (L) about 11L

2. Common faults and inspection method

When any trouble occurs in your steering system,

please perform a preliminary inspection first toclassify the existing trouble and feed the information

back to professional maintenance personnel faithfully

to ensure that you are talking about the same problem.

For example, in case of hard steering, you need to

indicate the details (whether it occurs during left

turning or right turning, it only occurs during turning

in situ or occurs steadily, it occurs only at a certain

point or there is no steering boost). Expressing the

problem clearly can help save time and improve

working efficiency.

If causes of the trouble are still not found, you can let

the professional maintenance personnel test-drive

your vehicle under conditions of safety and feasibility.

If he can not drive, please ask him to sit beside you.When you are driving, allow him to hold the steering

wheel to feel status of the steering fault directly,

during which you can show the problem to him.

Once you confirm that a steering trouble exists in the

steering system, please not be anxious to remove the

power steering gear or the oil pump because many

other components in the steering system may cause

steering fault in most cases. Instead, check the

following components first, finally, check the steering

gear.


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1. Check steering wheel and wheel. Check if steering

wheel is loose, tire pressure is appropriate, air

pressures at both sides are uniform, tires are worn or

damaged.

2. Check if front wheel alignment (caster, kingpin

inclination, camber and toe-in) conforms to complete

vehicle requirements. Check tightening of tie rod

and drag link, ball joint and kingpin.

3. Check oil pipes. Check oil pipes for replacement

requirement, oil inlet and outlet pipes for

misplacement, oil pipes for clogging, distortion and

undersize diameter, and oil circuit for unobstructed

state. If any trouble is found, be sure to replace oil

pipes.

4. Check oil reservoir and ensure that oil level reaches

correct position. Check oil pump belt for overstress or

slip. If any trouble is found, please adjust or replace

according to specifications.

Trouble First cause Inspection method

1. Tire pressures insufficient or unequal at two

sides.Replace tire or inflate.

2. Steering system components loose or worn. Tighten or replace.

3. Wheel hub bearing adjusted improperly or

worn.Adjust or replace.

Drift occurs during turning

4. Steering gear mounting bolt loose. Tighten.

1. Tire pressure insufficient. Inflate.

2. Front axle parts or kingpin fitted too tightly. Adjust

3. Front wheel alignment adjusted improperly. Adjust

4. Steering valve locked. Repair steering gear.

5. Steering gear adjusted too tightly. Adjust steering gear.

Poor righting ability

6. Foreign materials in steering gear too much.Clean inside of steering

gear.

1. Steering linkage connections too loose. Tighten loose parts.

2. Steering wheel and steering shaft fitted loosely. Tighten loose parts.

3. Clearance between screw rod and nut or rack

and geared sector excessive.Repair steering gear.

Excessive free stroke of

steering wheel

4. Steering gear bracket loose. Tighten.1. Air in system. Bleed.

2. Leakage from one side of steering gear

excessive.Repair steering gear.

3. Tire pressures at two sides unequal. Inflate and adjust.

Steering heaviness occurs

at one side

4. Tire kingpins and cambers at two sides unequal.Adjust complete vehicle

parameters.


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Trouble First cause Inspection method

1. Air in system. Bleed.

2. Flow of steering oil pump too small.Remove and clean flow

control valve of oil pump.

3. Internal leakage of steering gear excessive. Repair steering gear.

4. Rotary valve locked (torsional deformation of

input shaft caused by impact).Repair steering gear.

5. Universal joint moving dully caused by

interference with steering column.Repair steering linkage.

6. Vehicle overload. Reduce load of vehicle.

7. Tire pressure insufficient. Inflate.

8. Strainer of oil reservoir damaged or clogged.Replace filter element and

clean piping system.

Steering heaviness occurs

at both sides

9. Oil in oil reservoir insufficient. Refill.

1. Stroke valve adjusted incorrectly.Check adjusted angle of

stroke valve.

2. Drag link adjusted incorrectly. Check length of drag link.Understeering

3. Fitting marks on pitman arm and steering arm

shaft not aligned.Reinstall.

1. Air in system. Bleed system.

2. Mechanical parts in system loose. Replace loose parts.

3. Flow of oil pump small. Adjust or replace.

4. Axial clearance of screw shaft too large. Adjust clearance.

Steering wheel strikeshand

5. Tire worn seriously or unevenly. Replace.

1. Brake forces unequal. Adjust brake force.

2. Tires worn or air pressures of left and right

wheels unequal.Replace tire or inflate.

3. Torsion bar pin of steering gear broken. Repair steering gear.

4. Flow of oil pump too large. Adjust or replace.

Wheels pull to one side in

fixed direction

5. Wheel hub bearing adjusted improperly. Adjust.

1. External leakage of steering gear. Replace sealing element.

2. Oil level in oil reservoir too high. Drain.

3. Oil reservoir gasket damaged. Replace.

4. Pipe joint gasket damaged. Replace.

External leakage

5. Oil pump drive shaft gasket damaged. Replace.

1. Air in system. Bleed.

2. Oil inlet and outlet pipes of system bending. Replace oil pipes.

3. Oil level in oil reservoir too low. Refill.

Abnormal noise

4. Steering oil pump damaged. Replace oil pump.


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Section Suspensions (Air Springs)1. Overview

In recent years, advantages of air suspension are getting acknowledged widely. Compared with common

suspensions, it can not only extend service life of vehicle but also improve comfort of complete vehicle. For

large-size buses, it can also decrease dynamic load of wheel to greatly reduce level of damage to road surface

caused by vehicle thus reducing maintenance and repair cost of highway surface. In addition, it enables vehicle

body height adjustment according to different demands. Current, air spring suspensions have been widely used

on vehicles of various kinds overseas and it rate of utilization on buses has reached above 95%. These vehicles

with air suspensions have snatched a big share in global automobile market. (The air spring is mainlydescribed here. Please refer to the Users Manual provided by the front axle manufacturer for the

detailed information and leaf spring.)2. Specifications

2-1 Table of Specifications of Front Air Suspension

Acting stroke of axleChassis

Model

Height of airbag

mm

Rated axle load

kgTotal stroke

mm

Up

mmDown mm

Center distance of air

spring mm

GL6111GR2 2505 5500 169 82 87 1244

2-2 Table of Specifications of Rear Air Suspension

Acting stroke of axle

Chassis

Model

Height of airbag

mm

Rated axleload

kg

Total stroke

mm

Up

mm

Down

mm

Center

distance of air

spring (lateral)

mm

Center distance

of air spring

(longitudinal)

Mm

GL6111GR2 2555 13000 188 85 103 1560 1628

2-3 Threaded connection tightening torque requirements

S/N Thread

SpecificationTorque Requirement Applied Position

1 M141.5 200N.m Stabilizer bar installation2 M141.5 100N.m(Maximum) Shock absorber installation

3 M161.5 350N.m Various supports installation

4 M181.5 100N.m Airbag upper cover installation

5 M181.5 100N.m Airbag & lower mounting installation

6 M181.5 440N.m Thrust rod installation

7 M201.5 650N.m Thrust rod support installation

8 M243 900N.m U-bolt tightening

Note: All the above states are the wet-state (lubrication state), and the torque shall be increased by 20%

if the tightening begins from the bolt head


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3 . Front Air Suspension

3-1 Structure diagram

3-2 Parts ListSN Parts name Quantity SN Parts name Quantity1 Frame support (adjustable) 1 23 Disc washer 8

2 Frame support (fixed) 1 24 Self-locking nut M161.5, Class 10 4

3 Leaf spring beam 2 25 Locating & adjusting bushing 2

3a Rubber bushing 26 Noise-reduction gasket 4

4 Protection pallet 2 27 Dowel pin 2

5 Connecting rod 2 28 Hexagon bolt M1670, Class 10.9 4

6 transversestabilizer bar 1 29 Self-locking nut M16, Class 10 4

7 Left locating plate 1 30 Welch plug 4

8 Right locating plate

1 31Hexagon bolt M20140 , Class 10.9

2

9 Air spring upper mounting plate 2 32 Welch plug 20 16

10 Air spring lower mounting plate 2 33 Self-locking nut M20, Class 10 16

11 Shock absorber lower support 2 34 Hexagon bolt M20100, Class 10.9 2

12 Left support 1 35 Hexagon bolt M20120, Class T1 9

13 Shock absorber assembly 2 36 Hexagon bolt M2080, Class 10.9 1

14 Air springassembly 2 37 Hexagon bolt 1-8, Class 5 2

15 Transverse torsion bar 1 38 Self-locking nut M1-8, Class B 2

16 Gusset plate 2 39 Nut 0.5''-13, Class B 2

17 Shock absorber upper support 2 40 S rin washers 0.5" 2

18 Torsion bar right support 1 41 Hexagon bolt M2090 , Class 10.9 2

20 Clam 2 42 Self-locking nut0.75''-10, Class B 2

21 Pad 2 43 Thin self-locking nut 0.75''-16, Class A 2

22 Rubber sleeve 8 44 Welch plug 0.75" 2


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4. Rear Air Suspension

4-1 Structure diagram

4-2 Parts List

SN Parts name Quantity Remark(The unit of tightening torque is NM) 1 Style 1 hexagon nut 12 M12, Class 10, torque 115

2 Spring washers 12

3 Clamp 2

4 pad 2

5 Stabilizer bar bushing 1

6 Transverse stabilizer bar 2

7 Hexagon head bolt 30 M1245, Class 10.9, torque 115

8 Hexagon head bolt 12 M1450, Class 10.9, torque 130

9 Spring washers 12

10 Reinforcement plate 2

11 V-rod frame support 2

12 Double-hole check spacer 8

14 V-shaped thrust rod 1

15 Cotter pins 4

16 Right adapter base welding assembly 1

17 Vertical tie rod 2

18 Vertical tie rod rubber sleeve 8

19 Disc washer 8

20 Hexagon slotted and castle nut, style 1 421 Style 1 all-metal hexagon nut 2 Torque 600

22 V-shaped axle support 1


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23 Hexagon head bolt 2 M24110, Class 10.9

24 U-bolts 4 M242405222, Class T1

25 U-bolt bracke 2

28 Stopper bracket welding assy 2

29 Stop block 2

30 Hexagon head bolt 4 M1230, Class 10.931 Style 1 hexagon nut 18 M8, Class 8

32 Spring washers 18

33 Hexagon nut 4 0.5"-13, Class B, torque 50

34 Spring washers 12 0.5"

35Rear left airbag guard welding

assembly1

/Rear right airbag guard welding

assembly1

36 Thin hexagon self-locking nut 4 0.75"-16, Class A, torque 50

37 Welch plug 4 0.75"

38 Air spring assembly 4

40 Hexagon head bolt 80.5"-131", 2 , 115

0.5"-131", Class 2, torque 115

41 Shock absorber assembly 4

42 Leveling valve 2

/ Pressure protection valve 1

43 Link 2 6280

44 Rubber plug 8

45 Left C-beam welding assembly 1

/ Right C-beam welding assembly 1

46 Left adapter base welding assembly 1

47 Cylindrical pin 4

48 Hexagon thick nut 8 M242, Class 10, torque 600

49 Shaft end cover 2

50 Three-hole check spacer 2

51 Straight track bar 2

51A Pin-shaped rubber ball head 2A 8t press machine is required while

replacement

51B Tubular rubber ball head 2 A 8t press machine is required whilereplacement

52 Longitudinal thrust rod frame support 2

53Front left airbag guard welding

assembly1

/Front right airbag guard welding

assembly1

Note: 1. In the Remark column, those indicated with the sign are the wearing parts2. The torque if not lubricated shall increase by 30%


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5. Installation & adjustment

Ensure quality of installation and adjustment of air

suspensions. The key points in quality control are:

A. Height of airbag: (refer to 2-1 and 2-2 Table of

Specifications).

B. After making sure that height of suspension,

position of axle or height of air spring is correct,

install lateral rod, longitudinal rod, straight rod, and

diagonal rod of front suspension.

When installing lower longitudinal rod of suspension,

ensure that there is no clearance between torsion bar

and frame support mounting surface side. Select

spacer for the other side according to clearance (one

piece for each place). After finish of the adjustment,

tighten the mounting nuts at both ends to the

specified torque. When installing upper longitudinal

torsion bar of suspension, select a spacer for the

clearance between the torsion bar and its mounting

surface on frame support to adjust installation slope

of front axle to specified value. Tighten the mounting

nuts at both ends to the specified torque.

When installing lateral torsion bar of suspension,

select a spacer for the clearance between the torsion

bar and its mounting surface on the support as

needed. Tighten the mounting nuts at both ends to

the specified torque.

Install straight rod to suspension first. Ensure that

there is no clearance between straight rod and

left/right mounting surface side. Select spacer for the

other side according to clearance (one piece for each

place). After straight rod has been installed properly,

install diagonal rod. Similarly, adjust length of

diagonal rod until just appropriate by adding spacer

to or removing spacer from the clearance between

diagonal rod and the mounting surface on front

support of left/right diagonal rod.

D. Tighten all fasteners for installation to the

specified torques. In case more than two fasteners

constitute a set, recheck tightening torque after they

have been tightened to the specified torque.

E. The height control valve should work and the

air spring should inflate and deflate normally.

F. After the air spring has been deflated

completely, there should be appropriate clearances

between tires and vehicle bottom surface and any

other parts (same when turning front wheel to left or

right extreme position).

G. When the air spring has been fully inflated

under full load condition, there should still be

adequate clearance around.

H. When installing height valve, note that the >

symbol on valve body should correspond to direction

of the drive link inserted into the valve body and the

drive link should move in the direction indicated by

the arrow of the symbol.

Note: The air springs on the chassis, especially front

axle air spring may reach height of suspension under

low pressure because of too low load, looking like

underinflation even going flat. This is normal.

6. Use

After a trouble-free operation test (approximate one

million kilometers) performed by customers, the air

suspension is proved to possess excellent

performance, serviceability, and extreme high

trouble-free running kilometers. In case of such

failures as air line leakage or accidental airbag

damage, the pressure protection valve in the air

circuit can still maintain adequate brake air pressure

on the vehicle and the buffer block in the air spring

can form a rubber pad support, so that you can still

drive the vehicle to the nearest service station safely

under low speed.

Correct use can reduce or avoid air suspension

malfunction.

The operating requirements for the air suspension

are:

6-1 Do not overload vehicle

It is not allowed to overload the air suspension. In

addition, when driving on such good road surfaces as

highway and a road, do not overload by more than

10%.

6-2 Maintain normal air supply pressure

The air supply pressure of the air suspension system

should be maintained within 5-8.5bar.

6-3 It is strictly forbidden to apply oil or grease


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on rubber parts

Do not apply lubricant or grease to any part of the air

suspension system. Especially, it is strictly forbidden

to use oil or grease on rubber parts.

6-4 Perform service and maintenance as

required

See Service and maintenance for details on related

specific requirements to service and maintenance.

7. Service & maintenance

7-1 Routine inspection & maintenance

7-1-1 Every day or before each trip, perform a

routine inspection to the air suspension (at the same

time when you perform routine inspection to other

components on the vehicle).

7-1-2 Items of the routine inspection include:

A. Visually check the air spring for adequate and

even inflation.

B. Height of the suspension is normal and there is

no leakage from the system.

Simple inspection method: When you take over the

vehicle from the manufacturer, park the vehicle

under sound conditions on a level ground, and

measure the distances between the four wheel

centers and the fixed points which can be easily

located on the body above the centers. Also, note the

four data properly. At each inspection after that, what

you need to do is to park the vehicle on a flat ground

simply and then measure and check the four data for

significant change. If no significant change is found,

it indicates that height of the suspension is normal

and there is no air leak from the system.

7-1-3 If it fails to pass the inspection, it is needed

to find out the cause and remove the trouble, repair it

if necessary. .

7-2 Periodic safety inspection

7-2-1 The periodic safety inspection can be

performed along with first class maintenance.

Kilometer interval: 1,500-2,000. Or you can perform

it at the safety inspection intervals specified for the

fleet.

7-2-2 When checking, park the vehicle on a

clean and flat ground (had better park it on an

inspection pit), then apply parking brake and block

wheels. (In the inspections and maintenances

described below, this provision is omitted).

7-2-3 Items of the safety inspection:

A. None of fasteners gets loose; there is no loose

soil, scale or metal wearer around bolt heads and

nuts; none of washers gets loose.

B. The air spring should inflate normally and the

compactness of the airbags at both sides of one and

the same axle should be uniform. Also, check the air

spring for wear, damage and inappropriate bulge and

adequate space and clearance around it; check and

clear such soils as sandstone and broken glass

adhering to outside of the piston on the air spring

base.

C. No oil leakage and damage should be found on

the shock absorber and it should work normally.

The simple method for determining that the shock

absorber works normally is thermal test for shock

absorber.

D. No cracks should be found on any part and

welding seam.


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8. Shock absorber

8-1 Shock absorber is the key component that is

most liable to wear

The function of the shock absorber in the air

suspension has varied greatly from that when it is in

a leaf spring suspension. Reason: Running speed of a

vehicle equipped with leaf spring is comparatively

low; acting stroke of a leaf spring suspension is

restricted; also, internal friction of a leaf spring

suspension is strong enough to automatically damp

vibration; therefore, load of the shock absorber is

comparatively low. To the contrary, vehicle speed of

a vehicle equipped with air suspension is high; acting

stroke of an air suspension is far too long; also,

internal loss of the suspension structure is low and

down stroke of the suspension is limited absolutely

by the shock absorber; therefore, the shock absorber

plays the key role in damping suspension vibration;

in addition, it receives extremely strong force, has

long piston stroke, high oil temperature and oil

pressure, and is liable to damage; in a word, shock

absorber is the key component that is most liable to

wear in an air suspension system.

8-2 Install the shock absorber with appropriatelymatched function

In a suspension system, shock absorber is designed

to match function of the whole system. A shock

absorber having appropriately matched function can

help reduce wear and damage of costly suspension

parts (e.g. air spring). It can also reduce tire wear and

damage to the parts in the cab and on the chassis

caused by vibration, and help reduce fatigue of the

driver to improve driving safety. Therefore, periodic

inspection and service to the shock absorber can help

avoid the unpredictable failures which will cause

forced stoppage of the vehicle and finally reduce

operation and maintenance cost of the vehicle.

Neither fail to replace a damaged or disabled shock

absorber nor install one that is of incorrect type and

has improperly matched function.

8-3 When will you replace shock absorber?

A. During a visual check, the shock absorber isfound damaged. For example:

Upper or lower mounting ring is damaged.

The bush in upper or lower mounting ring is

damaged.

The dust boot is damaged or it rubs or interferences

with the shock absorber body.

Bends (piston rod or body bends) or the body is

deformed or depressed.

Broken.

Leakage (oil leakage other than oil infiltration).

B. When any of the following symptoms is found,check the shock absorber carefully and perform a

thermal test for shock absorber to judge and replace

the damaged or disabled shock absorber.

The air spring is damaged or split.

Performance of the suspension deteriorates causing

excessive vehicle vibration.

Early damages of the parts in the cabin, the electric

device system and the cooling system.

Uneven tire wear.

8-4 Thermal test for shock absorber

Function of the shock absorber is to damp vibration

of the suspension system. In the process of vibration

damping, it converts the vibrational energy of the

suspension system to heat energy which will then be

shed. The working temperature range of the shock

absorber is from ambient temperature to around

176.Therefore, when you touch the shock absorber

after it works normally, you will found that it

changes from former lukewarm state to very hotstate.

In case no damage is found on the shock absorber

Dust boot

Body


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during visual check and you suspect that its inside is

damaged or disabled (abnormal working), the

simplest method is to perform a thermal test for

shock absorber to judge. Steps of the thermal test:

A. Run the vehicle under medium speed for at least

15 minutes.

B. After parking, immediately check. Touch the

chassis parts close to the shock absorber first to feel

temperature of metalwork in the environment, and

then touch dust boot and body of the shock absorber

carefully. The shock absorber dust boot working

normally is hotter than other parts while the shock

absorber body is hotter than the dust boot.

C. The temperature of a shock absorber having

internal fault is significantly lower than that of the

shock absorber at the other end of the same axle

(temperature difference between shock absorbers on

different axles does not mean shock absorber failure).

For a shock absorber of which temperature is visibly

low, remove it to check.

D. Shake the removed shock absorber and carefully

hear for metal impact sound from its inside. If any, it

indicates that inside of the shock absorber is

damaged.

8-5 Difference between oil leak and oil ooze of

shock absorber

Oil mist & oil ooze

After a period of time of use, temperature of the

hydraulic oil in inner chamber of the shock absorber

body will rise. The oil vapor evaporated will be

volatilized from the clearance between the piston rod

and the gasket. When the oil vapor contacts outside

cold air, it will condense on the shock absorber body

to form an oil mist film which will always adhere to

the whole shock absorber after mixing with flying

sand and dust on road.

In the oil ooze process, pressure of the oil at top of

inner chamber of the body will rise when the shock

absorber stretches. Then a little oil will adhere to the

piston rod and be pulled out of the gasket. In

subsequent compression stroke, part of the oil

adhering to the piston rod will be scraped off by the

gasket and left outside the gasket, so that the

gradually accumulated oil will flow down along the

shock absorber body.

Oil mist and oil ooze will occur inevitably when the

shock absorber works normally and they are also

necessary for normal working of the shock absorber

because forming process of oil mist and oil ooze

plays the role of lubrication and reduces friction and

heat to help extend service life of the gasket. In case

of positive confinement, no lubrication is enabled

between the piston rod and the gasket, so increased

friction force will cause the gasket to heat up and be

burned and damaged rapidly.

Oil leak

Oil leak means that a mass of oil flows out from the

gasket when the gasket is damaged or the damping

hole on the piston is clogged. When oil leak occurs,

very clear streams will be found at the body area

from the seal down, and hydraulic oil accumulated

until saturated accompanied by a thick layer of sticky

dirty oil can be seen. When checking, stretch the

shock absorber as possible as you can so as to see

status of the body top blinded by the dust boot.

Volume of the oil stored in the shock absorber should

be adequate (around 500ml above). Leakage to

certain extent is permissible. Adverse effect to

performance of the shock absorber will appear only

when the leakage exceeds 75ml.

In a word, immediately replace the shock absorber

on which oil leakage is found. The shock absorber on

which oil mist and oil ooze occurs has no

malfunction and requires no replacement. In addition,

do not mistake oil mist and oil ooze for oil leak

because it is difficult to differentiate oil ooze from

oil leak of the shock absorber. Replacement of a

normally working shock absorber will add

unnecessary maintenance cost.

9. Fault analysis & maintenance

Although the air suspension has excellent quality,

serviceability and extremely long trouble-free

running kilometers, some failures may occur on itdue to many factors such as installation, adjustment,

vehicle running and service and maintenance. To


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help customers enable troubleshooting after cause

analysis and save time and reduce maintenance and

repair cost as much as possible during service and

repair, the symptoms or status that may occur in the

air suspension system and possible causes of the

troubles are listed as follows:

9-1 Shock absorber failures & maintenance

9-1-1 Shock absorber failures

ALeakage

(Differentiate among oil mist, oil ooze and oil leak)

Height of suspension incorrect (too high or toolow).

Shock absorber installed incorrectly (for example,it is installed upside down or installation site of

shock absorber upper bracket is incorrect).

Model of shock absorber incorrect. Clearance around shock absorber insufficient. Vehicle used improperly; shock absorber workingunder overload; gasket damaged or worn

prematurely.

Gasket worn normally.BMounting ring of shock absorber outstretched orpulled open or shock absorber pulled to break.

Height of suspension too high. Shock absorber installed incorrectly (for example,installation site of shock absorber upper bracket is

too high).

Model of shock absorber incorrect. Vehicle used improperly (running under too highspeed on bad road surface or getting across such

obstacles as pit, channel and ridge under high

speed).

A. Bore of shock absorber bush worn, deformed orrubber ply damaged.

Suspension too high or too low or installedincorrectly.

Shock absorber installed incorrectly; mountingbolt not tightened or loose.

Model of shock absorber incorrect.D. Shock absorber bending (piston rod or body

bends); body depressed and deformed; dust boot

damaged.


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Model of shock absorber incorrect. Shock absorber installed incorrectly; installationsite of shock absorber upper bracket too low.

Model of air spring incorrect. Clearance around shock absorber insufficient;shock absorber impacted.

Description: The shock absorber is the part most

liable to wear. The repeated damage of which

causes can not be located and that occurs not

within a short time should be regarded as a

normal situation.

9-1-2 Maintenance

In case any of above failure occurs on a shock

absorber, replace it. Please follow the normal method

for vehicle repair to replace. The specific procedure

is as follows:

A. Remove upper and lower mounting bolts to take

off the shock absorber.

B. Replace with a new shock absorber, install

fasteners and tighten them to the specified torques.

Check length of the shock absorber. If the difference

between its length and the standard length is greater

than 6mm, check if height of the suspension or the

air spring is correct. When necessary, adjust height

of the suspension.

C. After you have driven for a certain kilometers,

check the shock absorber for normal operation.

Note: When replacing the shock absorber, be sure

to replace with a shock absorber matching former

model correctly; otherwise performance and

service life of the air suspension system will be

reduced and the air spring and the shock

absorber are likely to be damaged quickly. In case

a customer replaces with a shock absorber not

matching the former model by himself/herself, all

problems arising from this shall be the customers

sole liability.

9-2 Air spring failures

9-2-1 Types of air spring failures

AAir spring goes flat (not inflated).

Pressure of air reservoir too low to open pressureprotection valve.

Pressure protection valve failed or its filterelement too dirty.

Air control line leaky or clogged. Height control valve failed or its flexible linkgetting loose.


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BAirbag wear:

Flank is worn even penetrated to generate holes.

(as picture)

Clearance around air spring insufficient. Upper location adjusting block of frame supportsealing off or rubber bush in pin lug worn to cause

suspension drift resulting in friction between airbag

and tire, etc.

Interferential friction of airbag caused by shockabsorber damaged or line loose, etc.

. The area where airbag licks piston is worn to

generate lobe-shaped protuberance even holes.

Sandstone, broken glass, etc. adhering to outsideof the piston on air spring base.

CUpper margin plate of air spring is depressed.

Height of suspension too low; air spring workingunder low air pressure for an extended period of

time.

Height control valve failed or its flexible linkgetting loose.

Model of air spring incorrect (height is too high). Air supply pressure comparatively low; vehicle

overloaded seriously.

DUpper margin plate of air spring is raised.

Shock absorber failed or damaged or shockabsorber model incorrect.

Height control valve not working. Height of suspension too high; air spring workingunder above-normal air pressure for an extended

period of time.

Model of air spring incorrect (height is too low).ECracks or air leak occurs at joint between airbag

and upper margin plate or piston or air leak occurs at

root of screw or stud.

Air supply pressure too high causing seriousoverload.

Shock absorber failed, damaged or shockabsorber model incorrect; airbag overstretched.

Buffer contacting eccentrically causing localwear at joint between airbag and upper margin plate

or piston.


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F Air spring tilting; buffer pad contacting

eccentrically.

Air spring installed incorrectly; air spring askewlongitudinally.

Suspension installed incorrectly; air spring askewlaterally.

Upper location adjusting block of frame supportsealing off or rubber bush in pin lug worn to cause

suspension drift.

GCrowfoot cracks are found on airbag. Rubber aging prematurely caused by grease,solvent, etc. adhering to or coating on airbag.

Normal aging.HElasticity drops and gets harder and harder. Moisture in air reservoir not drained duly causingmore and more water to accumulate in air spring.

Description: Under normal service conditions,

service life of the air spring can be 3-5 years or

longer.

9-2-2 Replacement of air spring

A. Use a jack or a support seat to prop the frame at

the position about 51mm higher than normal height

of the suspension.

B. Bleed the air spring: Disconnect the mounting

bolt at lower end of the flexible link of the height

valve, turn control arm of the height valve down to

bleed air in the air spring, and then disconnect the

intake pipe on the air spring.

C. Remove damaged air spring.

D. Install a new air spring: attach upper margin plate

of the air spring to frame girder or upper mounting

plate of the air spring tightly, and then tighten

fasteners to the specified torque.

E. Connect air supply pipe of the air spring and

install the bolt at lower end of the flexible link of the

height control valve properly.

F. Remove the jack or support.

G. Start the engine to make system air pressure reach

shutoff pressure of the air pump, and then check the

system for air leak and the air spring for normal

inflation.

9-3. Height control valve failures

AVehicle tilts.

Height control valve adjusted improperly. In caseof significant differences between heights of

suspensions on front and rear shafts and their design

values, the vehicle will tilt longitudinally; in case of

excessive difference between heights of the

suspensions at both sides of one and the same axle

controlled by the height control valve, the vehicle

will tilt laterally.

One height control valve malfunctioning or lineobstructed causing the airbag under its control not to

inspire or exhaust (airbag is either low or high).

BLocking nut of the link is loose causing the link to

be pulled open.

Model of link incorrect or link installedimproperly; length of thread of flexible joint

screwed in connecting pipe too short.

Two locking nuts on link not tightened; threadloose.

CValve responds slowly.

Air supply pressure too low. Height control valve dirty and/or line dirty ordeformed.

Moisture in air reservoir not drained duly; valveand/or line frozen due to moisture in air in freezing

days.

Bore of line and/or joint too small.9-4. Suspension truss failures

9-4-1 Types of suspension truss failures

AWheel track deflects; tire is worn excessively.

Front axle and/or rear axle positioned incorrectly. Mounting bolt of thrust rod loose; rubber bush atend worn or damaged.


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Shock absorber damaged; performance ofsuspension deteriorating; vibration serious.

BVehicle runs unsteadily; it is difficult to control. Mounting bolt of thrust rod loose. Mounting bolt between front axle and adaptiveseat loose; weld between rear axle and adaptive seat

of axle sealing off.

Mounting bolt of thrust rod loose; rubber bush inend of thrust rod damaged, or mounting bolts of left

and right supports at both ends loose, or torsion bar

axle support sealing off.

9-4-2 Replacement & adjustment of thrust rod

The

gdw6115k chassis workshlp manual (gl6111gr2)

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