tkd final report (expressors)

8/11/2019 Tkd Final Report (Expressors)

1/38

Project Report

SUBMITTED BY

Varun Chandiok GB Pant Engineering College

Deepak Kukreja GB Pant Engineering College

Anshul Kumar Netaji Subhash Institute of Technology

Expressers used in Loco


2/38

1

TABLE OF CONTENTS

INDIAN RAILWAYS #

INTRODUCTION #

HISTORY #

ROLLING STOCK #

CLASSIFICATION OF LOCOMOTIVES #

DIESEL SHED TUGHLAKABAD - TKD #

INTRODUCTION #

SHED LAYOUT #

DTC #

CHAPTER 3 #

SECTION 3.1 #

SECTION 3.2 #

SECTION 3.3 #


3/38

2

INTRODUCTION

Indian Railways is an Indian state-owned enterprise, owned and operated by the Government of India

through the Ministry of Railways. It is one of the world's largest railway networks comprising 115,000 km

(71,000 mi) of track over a route of 65,000 km (40,000 mi) and 7,500 stations. In 2011, IR carried over 8,900

million passengers annually or more than 24 million passengers daily (roughly half of which were suburban

passengers) and 2.8 million tons of freight daily.

Inmy view Indian Railways has an immense untapped potential

- Lalu Prasad Yadav

Indian Railways is the world's ninth largest commercial or utility employer, by number of employees, with

over 1.4 million employees. As for rolling stock, IR holds over 239,281 Freight Wagons, 59,713 PassengerCoaches and 9,549 Locomotives (43 steam, 5,197 diesel and 4,309 electric locomotives).

HISTORY

The history of rail transport in India began in the mid-nineteenth century. The core of the pressure for

building Railways In India came from London. In 1848, there was not a single kilometer of railway line in

India. A British engineer, Robert Maitland Brereton, was responsible for the expansion of the railways from

1857 onwards. The Allahabad-Jabalpur branch line of the East Indian Railway had been opened in June

1867. Brereton was responsible for linking this with the Great Indian Peninsula Railway, resulting in a

combined network of 6,400 km (4,000 mi). Hence it became possible to travel directly from Bombay to

Calcutta.

At the opening ceremony, Viceroy Lord Mayo concluded that

it was thought desirable that, if possible, at the earliest possible moment, the whole

country should be covered with a network of lines in a uniform system.

Indian Railways


4/38

3

In 1920, with the network having expanded to 61,220 km (38,040 mi), a need for central management

was mooted by Sir William Acworth. Based on the East India Railway Committee chaired by Acworth,

the government took over the management of the Railways and detached the finances of the Railways

from other governmental revenues.

ROLLING STOCK

As for rolling stock, IR holds over 239,281 Freight Wagons, 59,713 Passenger Coaches and 9,549

Locomotives (43 steam, 5,197 diesel and 4,309 electric locomotives). The trains have a 5 digit

numbering system as the Indian Railways runs about 10,000 trains daily. As of 31 March 2013, 23,541

km (14,628 mi) (36%) of the total 65,000 km (40,000 mi) route length was electrified.[4] Since 1960,

almost all electrified sections on IR use 25,000 Volt AC traction through overhead catenary delivery.

ocomotives

Locomotives in India consist of electric and diesel locomotives. The class name includes this

information about the locomotive. It comprises 4 or 5 letters. The first letter denotes the track gauge.

The second letter denotes their motive power (Diesel or Electric) and the third letter denotes the kind of

traffic for which they are suited (goods, passenger, mixed or shunting). The fourth letter used to denote

locomotives' chronological model number. However, from 2002 a new classification scheme has been

adopted. Under this system, for newer diesel locomotives, the fourth letter will denote their horsepower

range. Electric locomotives don't come under this scheme and even all diesel locos are not covered.

For them this letter denotes their model number as usual.

A locomotive may sometimes have a fifth letter in its name which generally denotes a technical variant

or subclass or subtype. This fifth letter indicates some smaller variation in the basic model or series,

perhaps different motors, or a different manufacturer. With the new scheme for classifying diesel

locomotives (as mentioned above) the fifth item is a letter that further refines the horsepower indication

in 100 hp increments: 'A' for 100 hp, 'B' for 200 hp, 'C' for 300 hp, etc. So in this scheme, a WDM-3Arefers to a 3100 hp loco, while a WDM-3D would be a 3400 hp loco and WDM-3F would be 3600 hp

loco.

WDP4B

W : Wide Gauge

D : Diesel

P : Passenger

4 : 4000 HP

B : +200 HP

Wide gauge 4200HP

diesel engine


5/38

4

CLASSIFICATION OF LOCOMOTIVES

Locos, except of older steam ones, have classification codes that identify them. This code is the form

[gauge][power][load][series][subtype][suffix].

1. [gauge] is a single letter identifying the gauge the locos runs on :

W : Broad Gauge (1.67m)

Y : Meter Gauge (1m)

Z : Narrow Gauge(0.762m)

N : Narrow Gauge (0.61m)

2. The second item, [power] is one or two letters identifying the power source:

D : Diesel Powered

C ; DC Traction

A : AC Traction

CA : Dual Power AC/DC Traction

3. The third item, [load] is a single letter identifying the kind of load the loco is normally used for:

P : Passenger

M : Mixed Load

G : Goods

S : Shunting U : Multiple unit (DEMU/MEMU)

4. The fourth item, [series], is a digit identifying the horse power range of the loco, with 3 for

locos with over 3000hp but less than 4000hp, 5 for locos over 5000hp but less than

6000hp,etc. This new scheme was applied to all passenger/goods/mixed-haul diesel locos in

June2002, except for the WDM-2 and WDP-1 classes of locos.

5. The fifth item, [subtype], is an optional letter or number (or to of them) that further refines the

horse power indication in 100hp increments: A for 100hp, B for200hp, C for 300hp, etc. So

in this scheme, a WDM-3A refers to a 3100hp loco, while a WDM-3F would be a to a 3100hp

loco, while a WDM-3F would be a 3600hp loco.

6. The last item, [suffix], is an optional indication that indicates something special about the loco,

such as a different gearing ratio or brake system usual.


6/38

5

INTRODUCTION

It is a place where repair and maintenance work of diesel locomotives is carried out so as to increases

its life and efficiency and to reduce line failures to a minimum extent.

Tughlakabad is one such premier shed in Northern Railways homing 162 Diesel Locos. Because of its

geographical location, and being in the capital, it serves a large number of Mails /Express trains which

across the length & breadth of the country casting to goods operation.

Diesel Shed, Tughlakabad is spread over an area of 1,10,000 m 2 out of Which 10,858 m2

is covered.

Diesel Shed, Tughlakabad was established in the year 1970 with a planned holding of 75

locomotives and initial holding of 26 WDM2 locomotives.

Today, after 40 years of its existence, the shed has grown to a total holding of 162 locomotives of five

types, which include 59WDM2 (2600HP) 21 WDM4 (3100HP) 02 WDM2 (3300HP), 51 WDP1

(2300HP) and 29WDP3 (3100HP).

Shed is maintaining a mail link of 122 locos, which is highest for any shed on Indian railways. Some of

the important and prestigious trains being run by the shed are: Jammu Tawi and Guwahati Rajdhani

express, Shatabdi express for Amritsar, Dehradun and Ajmer, Puja Express, Uttar Sampark kranti,

Lucknow Mail, Kashivishwanath, Sharamjivi Express and the tourist train palace-on-wheels.

SHED LAYOUT

The shed has a total berthing capacity for 17 locomotives under 4 covered bays. The main bays are:-

1. The subassemblies section

2. The heavy repair and bogie section (3 berths for heavy repairs & 2 lifting points)

3. Mail running repair bay (6 berths).

4. Goods and out of course running repair bay (6 berths)

There is one old steam shed, which has recently been connected. This shed has a capacity for berthing

4 locomotives and is not equipped with lighting and overhead crane. This shed can hence be used for

light repairs only.

Diesel Locoshed Tughlakabad


7/38

6

DTC

Diesel training center at Tughlakabad was set in 1975 in premises of diesel shed, Tughlakabad

northern railway with a view to train diesel running staff as well as diesel maintenance to improve

overall efficiency of railway workers quality by upgrading the knowledge of railway workmen by starting

few courses.

INFRASTRUCTURE

DIESEL TRAINING CENTER

There are five classrooms ,a big hall and a model room with cut models (with working and non-working

types of various important components of locomotives such as expressor, cylinder head, turbo super

charger, water pump, lube oil pump, governor, etc. for better understanding. A well-qualified team of

trainers from maintenance and running is available for providing training.

DIESEL FAULT SIMULATOR

It comprises of actual electric panel, cut model of engine block(in working) and test benches. It helps n

improving, analyzing and understanding trouble-shooting knowledge of running staff as well as

maintenance staff

LOCOMOTIVES AT SHED

Today, after 40 years of its existence, the shed has grown to a total holding of 162 locomotives of five

types, which include 59WDM2 (2600HP) 21 WDM4 (3100HP) 02 WDM2 (3300HP), 51 WDP1

(2300HP) and 29WDP3 (3100HP).

Shed is maintaining a mail link of 122 locos, which is highest for any shed on Indian railways. Some of

the important and prestigious trains being run by the shed are: Jammu Tawi and Guwahati Rajdhani

express, Shatabdi express for Amritsar, Dehradun and Ajmer, Puja Express, Uttar Sampark kranti,

Lucknow Mail, Kashivishwanath, Sharamjivi Express and the tourist train palace-on-wheels.

WDM2 - 2600 HP

WDP1 - 2300 HP

WDP3A - 3100 HP

WDM3A - 3100 HP

WDM3C - 3300 HP


8/38

7

MAINTENANCE SCHEDULE

For the proper functioning of diesel shed and to reduce the number of failures of diesel locos, there

is a fixed plan for every loco, at the end of which the loco is checked and repaired. This process is

called scheduling. There are two types of schedules which are as follows:-

1. Major schedules

2. Minor schedules

MINOR SCHEDULES

Schedule is done by the technicians when the loco enters the shed.

After 15 days there is a minor schedule. The following steps are done every minor schedule &

known as SUPER CHECKING.

The lube oil level & pressure in the sump is checked.

1. The coolant water level & pressure in the reservoir is checked.

2. The joints of pipes & fittings are checked for leakage.

3. The check super charger, compressor &its working.

4. The engine is checked thoroughly for the abnormal sounds if there is any.

5. F.I.P. is checked properly by adjusting different rack movements.

This process should be done nearly four hour only. After this the engine is sent in the mail/goods

running repairs by for repairs. There are following types of minor schedules:-

1. T-1 SCHEDULE AFTER 15 DAYS



4. M-2 SCHEDULE AFTER 60 DAYS







9/38

8

TESTING-1

1. Fuel oil & lube check.

2. Expressor discharge valve.

3. Flexible couplings bubbles.

4. Turbo run down test.

5. Super checking.

TESTING-2

1. All the valves of the expressor are checked.

2. Primary and secondary fuel oil filters are checked.

3. Turbo super charger are checked.

4. Under frame are checked.

5. Lube oil of under frame checked.

MONTHLY-2 SCHEDULE

1. All the works done in T-2 schedule.

2. All cylinder head valve loch check.

3. Sump examination.

4. Main bearing temperature checked.

5. Expressor valve checked.

6. Wick pad changed.

7. Lube oil filter changed.

8. Strainer cleaned.

9. Expressor oil changed.


10/38

9

MAJOR SCHEDULES

MONTHLY-4 SCHEDULE

1. Injector changed.

2. Taped facing blowing.

3. Chang of total lube oil.

SECTIONS IN THE SHED

The whole shed is divided into various sections depending upon the Type of work. These section

assist in the repair are maintenance work of the locos.

These assisting sections may be divided into two main groups:-

1. Directly assisting sections.

2. Indirectly assisting sections.

DIRECTLY ASSISTING SECTIONS:-

These sections which directly assist in the maintenance work of the loco are called Directly

assisting sections. These sections play an important role in the maintenance work. The Directly

assisting sections are as follows:-

1. Turbo super charger section.

2. Expresser section.

3. Bogie section.

4. Cylinder head section.

5. Power pack section.

6. Speedometer section.

7. F.I.P section.

8. Air brake section.

9. Fuel section.

10. Pit wheel lathe section.

11. Traction motor and generator section.


11/38

10

1. TURBO SUPER CHARGER SECTION

INTRODUCTION

The diesel engine produces mechanical energy by converting heat energy derived from burning

of fuel inside the cylinder. For efficient burning of fuel, availability of sufficient air in proper ratio is a

prerequisite.

In a naturally aspirated engine, during the suction stroke, air is being sucked into the cylinder from the

atmosphere. The volume of air thus drawn into the cylinder through restricted inlet valve passage,

within a limited time would also be limited and at a pressure slightly less than the atmosphere. The

availability of less quantity of air of low density inside the cylinder would limit the scope of burning offuel. Hence mechanical power produced in the cylinder is also limited.

An improvement in the naturally aspirated engines is the super-charged or pressure charged engines.

During the suction stroke, pressurized stroke of high density is being charged into the cylinder through

the open suction valve. Air of higher density containing more oxygen will make it possible to inject more

fuel into the same size of cylinders and produce more power, by effectively burning it.

A turbocharger, or turbo, is a gas compressor used for forced-induction of an internal combustion

engine. Like a supercharger, the purpose of a turbocharger is to increase the density of air entering the

engine to create more power. However, a turbocharger differs in that the compressor is powered by a

turbine driven by the engine's own exhaust gases.

TURBO SUPERCHARGER AND ITS WORKING PRINCIPLE

The exhaust gas discharge from all the cylinders accumulate in the common exhaust manifold at

the end of which, turbo- supercharger is fitted. The gas under pressure there after enters the turbo-


12/38

11

supercharger through the torpedo shaped bell mouth connector and then passes through the fixed

nozzle ring. Then it is directed on the turbine blades at increased pressure and at the most suitable

angle to achieve rotary motion of the turbine at maximum efficiency. After rotating the turbine, the

exhaust gas goes out to the atmosphere through the exhaust chimney. The turbine has a centrifugal

blower mounted at the other end of the same shaft and the rotation of the turbine drives the blower at

the same speed. The blower connected to the atmosphere through a set of oil bath filters, sucks airfrom atmosphere, and delivers at higher velocity. The air then passes through the diffuser inside the

turbo- supercharger, where the velocity is diffused to increase the pressure of air before it is delivered

from the turbo- supercharger.

Pressurizing air increases its density, but due to compression heat develops. It causes expansion and

reduces the density. This results in supply of high-density air to the engine. To take care of this, air is

passed through a heat exchanger known as after cooler. The after cooler is a radiator, where cooling

water of lower temperature is circulated through the tubes and around the tubes air passes. The heat in

the air is thus transferred to the cooling water and air regains its lost density. From the after cooler air

goes to a common inlet manifold connected to each cylinder head. In the suction stroke as soon as the

inlet valve opens the booster air of higher pressure density rushes into the cylinder completing the

process of super charging.

The engine initially starts as naturally aspirated engine. With the increased quantity of fuel injection

increases the exhaust gas pressure on the turbine. Thus the self-adjusting system maintains a proper

air and fuel ratio under all speed and load conditions of the engine on its own. The maximum rotational

speed of the turbine is 18000/22000 rpm for the Turbo supercharger and creates max. Of 1.8 kg/cm2

air pressure in air manifold of diesel engine, known as Booster Air Pressure (BAP). Low booster

pressure causes black smoke due to incomplete combustion of fuel. High exhaust gas temperature due

to after burning of fuel may result in considerable damage to the turbo supercharger and other

component in the engine.

MAIN COMPONENTS OF TURBO-SUPERCHARGER

Turbo- supercharger consists of following main components.

Gas inlet casing.

Turbine casing.

Intermediate casing

Blower casing with diffuser

Rotor assembly with turbine and rotor on the same shaft.


13/38

12

ROTOR ASSEMBLY

The rotor assembly consists of rotor shaft, rotor blades, thrust collar, impeller, inducer, centre studs,

nosepiece, locknut etc. assembled together. The rotor blades are fitted into fir tree slots, and locked by

tab lock washers. This is a dynamically balanced component, as this has a very high rotational speed.

2. EXPRESSOR (6CD,4UC COMPRESSOR EXHAUSTER)

INTRODUCTION

In Indian Railways, the trains normally work on vacuum brakes and the diesel locos on air brakes. Assuch provision has been made on every diesel loco for both vacuum and compressed air for operation

of the system as a combination brake system for simultaneous application on locomotive and train.

In ALCO locos the exhauster and the compressor are combined into one unit and it is known as

EXPRESSOR. It creates 23" of vacuum in the train pipe and 140 PSI air pressure in the reservoir for

operating the brake system and use in the control system etc.


14/38

13

The expressor is located at the free end of the engine block and driven through the extension shaft

attached to the engine crank shaft. The two are coupled together by fast coupling (Kopper's coupling).

Naturally the expressor crank shaft has eight speeds like the engine crank shaft. There are two types of

expressor are, 6CD,4UC & 6CD,3UC. In 6CD,4UC expressor there are six cylinder and four exhauster

whereas 6CD,3UC contain six cylinder and three exhauster.

WORKING OF EXHAUSTER

Air from vacuum train pipe is drawn into the exhauster cylinders through the open inlet valves in the

cylinder heads during its suction stroke. Each of the exhauster cylinders has one or two inlet valves

and two discharge valves in the cylinder head. A study of the inlet and discharge valves as given in a

separate diagram would indicate that individual components like (1) plate valve outer (2) plate valve

inner (3) spring outer (4) spring inner etc. are all interchangeable parts. Only basic difference is that

they are arranged in the reverse manner in the valve assemblies which may also have different size

and shape. The retainer stud in both the assemblies must project upward to avoid hitting the piston.

The pressure differential between the available pressure in the vacuum train pipe and inside the

exhauster cylinder opens the inlet valve and air is drawn into the cylinder from train pipe during suction

stroke. In the next stroke of the piston the air is compressed and forced out through the discharge

valve while the inlet valve remains closed. The differential air pressure also automatically open or

close the discharge valves, the same way as the inlet valves operate. This process of suction of air

from the train pipe continues to create required amount of vacuum and discharge the same air to

atmosphere. The VA-1 control valve helps in maintaining the vacuum to requisite level despite

continued working of the exhauster.

COMPRESSOR

The compressor is a two stage compressor with one low pressure cylinder and one high pressure

cylinder. During the first stage of compression it is done in the low pressure cylinder where

suction is through a wire mesh filter. After compression in the LP cylinder air is delivered into the

discharge manifold at a pressure of 30 / 35 PSI. Workings of the inlet and exhaust valves are similar to

that of exhauster which automatically open or close under differential air pressure. For inter-cooling air

is then passed through a radiator known as inter-cooler. This is an air to air cooler where compressed

air passes through the element tubes and cool atmospheric air is blown on the outside fins by a fan

fitted on the expressor crank shaft. Cooling of air at this stage increases the volumetric efficiency of air

before it enters the high- pressure cylinder. A safety valve known as inter cooler safety valve set at 60

PSI is provided after the inter cooler as a protection against high pressure developing in the after

cooler due to defect of valves.

After the first stage of compression and after-cooling the air is again compressed in a cylinder of

smaller diameter to increase the pressure to 135-140 PSI in the same way. This is the second stage

of compression in the HP cylinder. Air again needs cooling before it is finally sent to the air reservoir

and this is done while the air passes through a set of coiled tubes after cooler.


15/38

14

3. BOGIE SECTION

This is the part (called the bogie) carrying the wheels and traction motors of the locomotive. A pair of

train wheels is rigidly fixed to an axle to form a wheel set. Normally, if two wheel sets are mounted in abogie it is known as BO-BO type, but if three wheel sets are mounted on truck, it is called as CO-CO

type. Most bogies have rigid frames as shown below.

The bogie frame is turned into the curve by the leading wheel set as it is guided by the rails. However,

there is a degree of slip and a lot of force required to allow the change of direction. The bogie carries

about half the weight of the vehicle it supports. It also guides the vehicle, sometimes at high speed, into

a curve against its natural tendency to travel in a straight line. They provide the propulsion, the

suspensions and the braking. As you can imagine, they are tremendous structures.

The trucks also provide the suspension for the locomotive. The weight of the locomotive rests on a big,

round bearing which allows the trucks to pivot so the train can make a turn. Below the pivot is a huge

leaf spring that rests on a platform. The platform is suspended by four, giant metal links, which connectto the boogie assembly. These links allow the locomotive to wing for side to side.

The weight of the locomotive rests on the Helical springs and Leaf spring, which compress when it

passes over a bump. The links allow the trucks to move from side to side with fluctuations in the truck.

The truck is not perfectly straight, and at high speeds, the small variations in the track would make for a

rough ride if the trucks could not swing laterally. The system also keeps the amount of weight on each

rail relatively equal, reducing wear on the tracks and wheels.

There are three pivots on which the load is distributed as 60%, 20%, 20% respectively on centre pivot,

on two side bearers which are elliptical in shape. For distributing the load equally on the axles the

equalizer beams are used.

While running the defects which generally occur are:-

1. Crack in equalizer due to stress concentration.

2. Breaking of centre pivot due to inertia force.

3. There might be failure of spring.


16/38

15

4. CYLINDER HEAD SECTION

INTRODUCTION

The cylinder head is held on to the cylinder liner by seven hold down studs or bolts provided on thecylinder block. It is subjected to high shock stress and combustion temperature at the lower face, which

forms a part of combustion chamber. It is a complicated casting where cooling passages are cored for

holding water for cooling the cylinder head. In addition to this provision is made for providing passage

of inlet air and exhaust gas. Further, space has been provided for holding fuel injection nozzles, valve

guides and valve seat inserts also.

COMPONENTS OF CYLINDER HEAD

In cylinder heads valve seat inserts with lock rings are used as replaceable wearing part. The

inserts are made of stellite or weltite. To provide interference fit, inserts are frozen in ice and cylinder

contact. (In the latest engines the inlet valves are ground at 30 and seats are

ground at 29.5). Each cylinder has 2 exhaust and 2 inlet valves of 2.85" in dia. The valves have stem

of alloy steel and valve head of austenitic stainless steel, butt-welded together into a composite unit.

The valve head material being austenitic steel has high level of stretch resistance and is capable of

hardening above Rockwell- 34 to resist deformation due to continuous pounding action.

The valve guides are interference fit to the cylinder head with an interference of 0.0008" to 0.0018".

of cylinder heads is done in ALCO engines with a torque value of 550 Ft.lbs. The cylinder head is a

metal-to-metal joint on to cylinder.

ALCO 251+ cylinder heads are the latest generation cylinder heads, used in updated engines, with the

following feature:

Fire deck thickness reduced for better heat transmission.

Middle deck modified by increasing number of ribs (supports) to increase its mechanical

strength. The flying buttress fashion of middle deck improves the flow pattern of water

eliminating water stagnation at the corners inside cylinder head.


17/38

16

Water holding capacity increased by increasing number of cores (14 instead of 11)

Use of frost core plugs instead of threaded plugs, arrest tendency of leakage.

Made lighter by 8 kgs (Al spacer is used to make good the gap between rubber grommet and

cylinder head.)

Retaining rings of valve seat inserts eliminated.

BENEFITS:-

Better heat dissipation

Failure reduced by reducing crack and eliminating sagging effect of fire deck area.

MAINTENANCE AND INSPECTION

Cleaning: By dipping in a tank containing caustic solution or ORION-355 solution with

water (1:5) supported by air agitation and heating.

Crack Inspection: Check face cracks and inserts cracks by dye penetration test.

Hydraulic Test: Conduct hyd. test (at 70 psi, 200F for 30 min.) for checking water leakage at

nozzle sleeve, ferrule, core plugs and combustion face.

Dimensional check :

Face seat thickness: within 0.005" to 0.020"

Straightness of valve stem: Run out should not exceed 0.0005"

Free & Compressed height (at 118 lbs.) of springs: 3 13/16" & 4 13/16"

Checks during overhauling:

Ground the valve seat insert to 44.5/29.5, maintain run out of insert within 0.002" with respect to valve

guide while grinding.

Grind the valves to 45/30 and ensure continuous hair line contact with valve guide by checking colour

match.

Ensure no crack has developed to inserts after grinding, checked by dye penetration test.

Make pairing of springs and check proper draw on valve locks and proper condition of groove and locks

while assembling of valves.

Lap the face joint to ensure leak proof joint with liner.

BLOW BY TEST:

On bench blow by test is conducted to ensure the sealing effect of cylinder head.


18/38

17

Blow by test is also conducted to check the sealing efficiency of the combustion chamber on a running

engine, as per the following procedure:

Run the engine to attain normal operating temperature (65C)

Stop running after attaining normal operating temperature.

Bring the piston of the corresponding cylinder at TDC in compression stroke.

Fit blow-by gadget (Consists of compressed air line with the provision of a pressure gauge and

stopcock) removing decompression plug.

Charge the combustion chamber with compressed air.

Cut off air supply at 70 psi. Through stop cock and record the time when it comes down to

zero.7 to 10 sec is OK.

SPEEDOMETER SECTION

In this section all the gauges of an engine are tested in every schedule. If they are not working properly

they are changed. In the checking process the memory card is checked and replaced. The memory

cards records the data of speed at every moment when the loco runs on the line. This information

makes the maintenance process much easier.

The control panel of WDM2 has:-

1. Two vacuum gauges

2. Two vacuum duplex

3. Two main reservoir duplex

4. Two air flow gauge

5. HS-4-gauge

6. Central air gauge


19/38

18

7. Fuel and lube oil gauge

F.I.P. SECTION

F.I.P. is one of the most important parts of the loco. It stands for fuel injection pump

Fine spray is needed for successful ignition of the fuel. So the fuel has to be pumped into the cylinder

ay high pressure.

The fuel pump is operated by a cam driven of the engine. The fuel is pumped into the injector which

injects the fuel in the form of very fine spray, required for combustion in the cylinder. For this purpose a

multipoint fuel injection system is used. Nozzle is made up brass and has nine holes through which the

fuel is sprayed uniformly.

So, the fuel injector is an important part of an engine. In the schedule the F.I.P. is overhauled. It is

disassembled and then checked for any distortion at a high pressure has to be maintaining at the time

of injection.

Nozzle is tested at the pressure of:-

New nozzle 3900 psi to 4050 psi

Old nozzle 3700 psi to 3800 psi


20/38

19

TESTING OF NOZZLE BY USING A HYDRAULIC PRESS.

Spray pattern of the fuel should be uniform. There should be noise of chattering at testing. The nozzle

holes are cleared by 0.3mm diameter wire. The pressure of injection can be changed by adding or

removing the compensating washers (shim) which are available in different thickness. The nozzle is

tested at following specific data:-

Nozzle tip dia 0.44-0.65mm

R.P.M. 500

Stroke 300

Temp. 100-1200 C

Pressure 40psi

Viscosity 6.8-7.1 cst at 300 C

After the testing high pressure tubes in N.D.T lab the F.I.P. is cleared.

FUEL SECTION

This section deals with the fuel transaction. It delivers the report to the management & passes its

requirement. The oil comes from IOC, BPC, and HPC. The total oil expenditure of 4700 crore

rupees/year is a big amount so this is one of the most concentrating fields for the government. So a

report is sent to the head office daily.

The oil comes to the shed by road or by train. When the oil comes to the shed many data are to be

filled and sent to head office as the quantity of oil, capacity, date of loading unloading etc. are prepared

in the presence of government inspector & the person from company.

Before unloading following thing are checked.

1. The oil is tested by lube oil lab.

2. The temperature at time of unloading and by multiplying by the temp. with the Correction

factor, the exact volume is calculated.

3. The moisture in the oil is checked.

Following important factors are considered by the fuel section.

1. Fuel consumption rate of shed. (gross tone/kilometer, per unit tone/kilometer)

2. Economic factor.

3. Maintaining safety standard.

4. Oil testing.

5. Temp. correction factor.

6. Wastage allowed only 0.001%.


21/38

20

For further records fuel trip cards are maintained by the driver in this lube oil change, fuel oil are filled

by the driver & kept in record. These all records came in major schedule & send to major head office.

The oils used are:-

HSD High speed diesel as fuel oil

RR-813 Engine block lubes oil

RR 407 Expressor oil

T77 grade oil Governor, traction generator, wick lube

Cadmium compound gear & pinion on axle, fast coupling

PIT WHEEL LATHE SECTION

When the loco is on line there are many types of tracks in the way on which driver has to apply brakes.

At the time of braking there are many possibilities of skidding due to sudden braking. When two metals

slide upon each other the wear of both the metal occurs. So due this reason the wheel wears when this

wear flatness exceed 50mm of length, then the wheel needs treatment. The wheel are machined in this

section. So, for making the wheel perfectly round the wheel are send to this section. The lathe is

installed in pit, hence is the name Pit Wheel Lathe.


22/38

21

TRACTION MOTOR AND GENERATOR SECTION

This giant engine is hooked up to an equally impressive generator. It is about 6 feet (1.8m) in diameter

and weighs about 17,700 pounds (8029kg). at peak power this generator makes enough electricity to

power a neighborhood of about 1,000 houses.

So, where does all the power go? It goes into six, massive electric motors located in the bogies.

The engine rotates the crank shaft at up to 1000rpm and this drives the various items need to power

the locomotive. As the transmission is electric the engine is used as the power source for the electricity

generator or alternator.

MAIN ALTERNATOR

The diesel engine drives the main alternator which provides the power to move the train. The alternator

generator AC electricity which is used to provide for traction motors mounts of the axles of the bogies.

In older locomotives, the alternator was a DC machine, called a generator. It produce direct currentwhich was used to provide power for DC traction motor. Many of these machines are still in regular use.

the next development was the replacement of the generator by the alternator but still using DC traction

motor. The AC output is rectified to give the DC required for the motors.

AUXILIARY ALTERNATORS

Locomotives used are equipped with auxiliary alternators. This provides AC power for lighting, air

conditioning, etc. on the train. The output is transmitted on the train through an auxiliary power line. The

output from the main alternator is AC but it can be used in locomotive with either DC or AC traction

motors. DC motors where the traditional type use for many years but, AC motors have become

standard new locomotives. They are cheaper to build and cost less to maintain and to convert the ACoutput from the main alternator to DC, rectifiers are required. If the motors are DC, the output from the

rectifiers is used directly. If the motors are AC the DC output from the rectifier is converted to 3-phase

AC for the traction motors.

TRACTION MOTORS

Since the diesel-electric locomotive uses electric transmission, traction motors are provided on the

axles to give the final drive. These motors where the traditionally DC but the development of modern

power and control electronics has led to the introduction of 3-phase AC motors. There are between four

& six motors on most diesel electric locomotives. A modern AC motors with air blowing can provide up

to 1000hp


23/38

22

INDIRECTLY ASSISTING SECTIONS

Those sections which indirectly assist in the maintenance work are called indirectly assisting sections.

The labs generally come under this sections. The various indirectly assisting section are as follows:-

1. Speedometer lab

2. Metallurgical lab

3. Machine shop

4. Millwright sections

5. C.T.A. cell

6. Control room

The brief introductions of these sections are given below.

SPEEDOMETER LAB

When the loco comes for a schedule, the lube oil of the loco checked thoroughly. When the metals

slides over each other. Sometimes they cause wear, but there is continuous flow of lube oil between

them which takes those particles with them. This increases the quality of different metals in them. So, in

this lab the different percentage of elements are taken out by electronics method. In this test, a very

thin film is created between two graphite electrodes having high potential difference between them.

This causes a spark between them which carries a high temperature (25000 C). this process is done in

UV-Rays. So the valence electrons of different element in outer shell get excited and jump to the

excited level. They remain there for 10-2 sec. when they come down to normal state they release

energy in the form of light rays. Different elements release different intensity waves which are focusedon a different grating, which splits the light into a spectrum. These spectrum lights are focused on the

potential tubes based on photo electric effect. This generates electric signals that are read & compared

by the computer to the standard data. The data is as follows:-

Elements Min. Limit in ppm) Max. limit in ppm)

Cu 10 20

Pb 5 10

Sn 5 10

Fe 20 50

Cr 5 10

Na 30 50

Al 5 10

Si 15 20

B 10 20

So according to these limits we can easily detect which metal is wearing more, and according to that

which part has to be checked and changed.


24/38

23

MACHINE SHOP

In this section machining of different parts is done. The machine shop has different lathe, grinding

machine, power hacksaw, drill machine & shaper machine. But the machining of very few components

like expresser shaft, generator armature is done and most of the parts are replaced because there is no

comprise for the efficiency.

METALLURGICAL LAB

In this section the properties of the lube oil & fuel oil are tested and if they are up to the mark then they

are only used.

The standard properties of the fluids are as follows:-

FUEL OIL PROPERTIES

Acidity nil

Pour point 3oC(winter)15oC(summer)

Distillation record(370oC) 95% min.

Flash point 35oC min.

Kinematic viscosity (40oC) 25 cst.

Density (15oC) 820-860 kg/m3

Sulphur max% by weight 0.25

Water max% by volume 0.05

Carbon residue % wise by weight 0.30

LUBE OIL PROPERTIES

Appearance clean & bright

Kinematic viscosity (100oC) 15.516.3 cst

Viscosity index - 110min.

Pour point - 21max

Flash point - 200oC

Sulphur - 1.39-1.63%


25/38

24

Different tests are conducted on the oil and their properties are tested out. If the readings are different

then the action is taken by the administration.

MILLWRIGHT SECTION

In this section the maintenance work of helping machine is done.

The maintenance of supporting machines are done as:-

1. Cranes.

2. Hydraulic jacks.

3. Air compressors.

4. Water compressors.

5. Air pipe lines.

C.T.A CELL

The information for any movement is necessary to be given to the head office. So there should be a

body which can form a like between administration and the shed. This is done by C.T.A cell.

The few main works are as:-

1. Interaction between H.O and shed.

2. To keep check of the technical view on the working in the shed.

3. To check the work quality according to the standards.

4. To solves the problem s of the sheds different departments.

5. To contact the concerned private agencies if there is some problems in their services.

6. To maintain the standard criteria of I.S.O as they need the six monthly contracts.

So, in this way C.T.A cell plays an important role of interaction between shed and administration.

CONTROL ROOM

There are several locos in the shed, so it is important to have a proper schedule to maintain them andto maintain proper outage of the shed. This work is done by the control room. It is the link between the

shed and each every loco. It forms an interface between the on line and the shed. Control room

maintains the record of each and every failure. They decide when a loco has to come back in shed and

when it has to besent on the line. For this they have maintained a system which automatically let them

know which loco is running where. If a loco fails on line then control room has to deal with it. So this is

the department which keeps the track of a loco at every moment.


26/38

25

INTRODUCTION

IN Indian Railways, the trains normally work on vacuum brakes and the diesel locos on air brakes. As

such provision has been made on every diesel loco for both vacuum and compressed air for operation

of the system as a combination brake system for simultaneous application on locomotive and train.

In ALCO locos the exhauster and the compressor are combined into one unit and it is known as

EXPRESSOR. It creates 22" of vacuum in the train pipe and 140 PSI air pressure in the reservoir for

operating the brake system and use in the control system etc.

The expressor is located at the free end of the engine block and driven through the extension shaft

attached to the engine crank shaft. The two are coupled together by splined flexible coupling (Kopper's

coupling)/Cardan shaft. Naturally the expressor crank shaft has eight speeds like the engine crank

shaft and runs between 400 RPM to 1000 RPM range.

CONSTRUCTION AND DESCRIPTION

The expressor consists of the following components mainly;

1. Crank Case

2. Crank shaft

3. Four/Three exhauster cylinders with cylinder heads

Expressers In Diesel Locomotives


27/38

26

4. One/Two low pressure compressor cylinder with cylinder

head.

5. One high pressure cylinder with cylinder head.

6. Six pistons with connecting rods (including one/two

LP, one HP and four/three exhausters.)

7. Lube oil pump.

Each of two crank journals supports three connecting rods. The crankshaft is supported at the both

ends by double row ball bearings. Outside the ball bearings are located oil seals to prevent the leakage

of oil from inside the crank case and air from out side into it. Crankcase breathers are provided to vent

the compressor crankcase.

MODELS OF EXPRESSORS USED IN DIESEL LOCOS

There are two models commonly used in Diesel Locos. They are

1. 6CD-4UC


28/38

27

2. 6CD-3UC

In 6CD-4UC Expressor, there are six cylinders out of which the one having smaller diameter acts as HP

and one LP and four exhausters while in 6CD-3UC, there are one HP, two LP and three exhausters.

In both models, the LP cylinder head and each exhaust cylinder head contains two inlet and two

discharge valves and the HP cylinder head contains one/two inlet and discharge valves. The valves are

such that they have liberal air flow passages to avoid flow restrictions and to prevent excessive heating

and choking of valve ports with carbon deposits due thermal decomposition of lube oil. The retainer

stud in both the assemblies must project upward to avoid hitting the piston. The inlet valves of both LP

and HP cylinders are equipped with unloaders which help to unload the compressor when the desired

pressure in the main air reservoir is reached. Similarly, the compressor cylinders are loaded whenever

there is a drop in air pressure.

WORKING

COMPRESSOR

The compressor is a two stage compressor with one LP cylinder and one HP cylinder. During the first

stage of compression it is done in the LP cylinder. As the piston of LP cylinder starts moving downward,

the combined action of discharge valve return springs

and the pressure differential existing between the

discharge manifold and the LP cylinder closes the

discharge valves. At same time inlet valves open due to

pressure differential existing between inside and outside

the LP cylinder. The atmospheric air is then sucked into

the cylinder through an intake strainer (wire mesh filter)

mounted horizontally. During the upward stroke of the

piston, the combined action of inlet valve springs and

pressure differential existing between inside and outside


29/38

28

the LP cylinder closes the inlet valves. The air present in

the cylinder above the piston is then compressed. Towards

the end of the upward stroke, the compressed air opens

the discharge valves due to the pressure differential

existing between the discharge manifold and the cylinder.

After compression in the LP cylinder air is delivered intothe discharge manifold at a pressure of 30 / 35 PSI. Thus

the compressed air reaches the intercooler which is of

radiator type cools the low pressure compressed air before

further compression in the HP cylinder. After the first stage

of compression and after-cooling the air is again

compressed in a cylinder of smaller diameter to increase the pressure to 135-140

PSI in the same way. This is the second stage of compression in the HP cylinder. Air again needs

cooling before it is finally sent to the air reservoir and this is done while the air passes through a set of

zigzag tubes below the loco superstructure. Thus finally the output of HP cylinder is discharged into the

main air reservoir.

LOADING AND UNLOADING OF COMPRESSOR

To avoid the compressor running hot due to

overloading and also to avoid the wastage of

engine horse power, arrangements are

provided to unload the compressor when a

particular pressure is reached. In other

words the compressor cylinders are not

required to compress air any further whenthe main reservoir pressure reaches

10kg/sq.cm. So the compressor stops

loading the main reservoir. Due to no

further compression being done, reservoir

pressure naturally falls due to normal

consumption and leakages. When the MR

pressure come down to 8kg/sq.cm. The

compressor resumes loading of the MR

again. Generally, the time taken for loading

and unloading should be in the ratio of 1:3.

Basically in these compressors unloading is

effected by the unloader plunger prongs

pressing down the inlet valves of both LP

and HP cylinders to keep them in open

position as soon as 10kg pressure is reached in the M.R. It continues to be so till the pressure comes

down to 8kg/sq.cm. Thus the compressor remains unloaded or relieved of load in the range between


30/38

29

10 to 8kg/sq.cm. MR pressure. In this case, the LP cylinder air drawn in through the intake filter is

thrown out in the same direction. In case of the HP cylinder air is pushed back to the inter cooler and

LP discharge manifold. This is achieved through the function of the unloader plunger in conjunction

with the air governor. The added advantage of unloading process is that the air which goes out without

getting compressed during the unloading process cools the system.

EXHAUSTER

Air from the vacuum brake pipe is drawn into the inlet side of the exhauster head. The inlet faces of the

exhauster heads are connected by two inlet manifolds. Two exhauster cylinders are attached to each

manifold. There are two inlet valves and two discharge valves in each cylinder head. During the

downward stroke of the piston, air is drawn through the inlet valves into the exhauster cylinders. The

pressure differential existing between inside and outside of the exhauster cylinders closes the

discharge valves. As the piston moves upward, the air is compressed slightly above the atmospheric

pressure and passes through the discharge valve into the discharge manifolds. During the upward

stroke, the combined action of the inlet valve return springs and pressure differential existing between

the vacuum reservoir and the exhauster cylinders will close the inlet valves. At the same time, thecompressed air will open the discharge valve near the end of upward stroke of the piston.

This process of suction of air from the train pipe continues to create required amount of vacuum which

is 23 inch of Hg and discharge the same air to atmosphere. The VA-1 Control Valve helps in

maintaining the vacuum to requisite level despite continued working of the exhauster.

LUBRICATION SYSTEM

The lube oil system of the expressor is a force feed pressure lubrication system, independent of the

lube oil system of the engine.

Lubricating oil of SAE 30 or SAE 40 grades is filled in the sump of 21lts. capacity. The lubricating oil is

filled through the filler assembly into the crankcase. An oil pump which is of chain-driven gear type

circulates the oil under pressure through the system as shown in fig. The oil pump is driven by a


31/38

30

sprocket mounted on one of the two pump gears which takes drive from the crank shaft of the

expressor through a sprocket and chain. A strainer screen which is held in place by screen retainer

filters the oil before oil is drawn up into the inlet port of the gear pump.

The oil after filtration is carried around the gears to where the gears mesh. The meshing action forces

the oil upward to the discharge port. A port takes the oil up to the groove in distributing ring of the oil

pump body.

From the distributing ring, oil flows to each crank-pin through drilled passages in the crankshaft. These

holes connect to distributing holes drilled axially through each crank-pin of the crankshaft. Each crank-

pin is cross drilled to supply oil to three connecting rods. This also provides lubrication for the six

connecting rod insert bearings. The top half of each insert bearing of the connecting rod is grooved and

ported to deliver oil to the wrist pin bushing and the cylinder liner

The oil pressure in the system is limited to 25-60 psi (40 psi at idle, 60 psi at full speed) by relief valve

located in the oil pump body. The relief valve is spring weighed and maintains the lubricating oil

pressure in the compressor at designed setting. When the oil line pressure exceeds, the relief valve is

unseated allowing oil to pass out to the sump. An oil pressure indicator gauge indicates the oil pressureof the system. The gauge is mounted on the side cover of the crankcase. Pressure reaches the gauge

by means of a tube leading from the lower pipe tap on the pump body to the gauge port in side cover.

The magnetic drain plugs one on either side of the crankcase is meant for draining oil from the

crankcase and to collect iron particles in the oil sump.

COOLING SYSTEM

Cooling in expressors is done at two stages. At the first stage, compressed air from LP cylinder is

cooled in the intercooler before going into the HP cylinder thereby increasing compressors volumetric


32/38

31

and overall efficiency. At the second stage, compressed air from the HP cylinder is cooled by passing it

through a set of zigzag tubes below the loco superstructure before going to the MR tank.

Intercooler is of adequate thermal capacity with large heat dissipation area consisting of finned tubing

mounted between cast iron headers which act as cooling ribs. This is an air to air cooler where

compressed air enters the top header and passes down in one half and comes up through the

remaining half of the tubes. Cool atmospheric air is blown on the outside fins by a fan fitted on the

expressor crank shaft. The fan also cools cylinder and cylinder heads. The direction of the air flow is

such that hot air from the diesel engine does not pass over the expressor. A safety valve set at 60 psi is

fitted to the intercooler to afford necessary protection to the intercooler and LP cylinder equipment

against excessive pressure.

AIR INTAKE STRAINER

The inlet air for LP cylinder of expressor is filtered by one horizontally mounted viscous type air intake

filter. The main parts of strainer filter are

1. Strainer element made of metal wire mesh.

2. Latch bail to hold the strainer element in position.

3. Strainer gasket.

4. Fittings to hold the complete strainer assembly on to the inlet side of the LP cylinder.

INLET AND DISCHARGE VALVES

All the inlet and discharge valves are of double disk type. The valves springs of inlet and discharge

valve assemblies are completely interchangeable. All inlet valve assembly has same valve seat; all

discharge assembly have same valve seat.The inlet valves of LP and HP cylinders are equipped with

unloaders which are controlled by governor.

PISTON

The LP and exhauster pistons are made of Aluminum alloy whereas HP piston is made of cast iron.

Four piston rings are fitted on each piston. The upper two rings are compression rings and other two

are oil rings.

CONNECTING ROD

Expressor has six identical connecting rods of forged steel. These are

mounted on each crankpin of the crankshaft. Each connecting rod has

replaceable insert bearings on the big end. The smaller end of LP and

exhauster connecting rods have bush bearings where as that of HP has

roller bearings.


33/38

32

CRANKSHAFT AND CRANKCASE

The crankshaft is coupled together by splined flexible coupling (Kopper's coupling)/Cardan shaft

directly to the diesel engine. The crankshaft dynamically balanced to ensure smoothness of operation,

is supported on two main bearings, one at each end of the crankshaft. The bearings are double row ball

ty

CRANKCASE

It is housing for crankshaft, connecting rods and lubrication system. It is under partial vacuum which is

achieved by connecting the crankcase to the inlet manifold of the exhauster by means of a pipe through

the vacuum maintaining valve to prevent oil throw through the exhaust.

VACUUM MAINTAINING VALVE

When there is a pressure buildup in the crankcase, the piston in the vacuum maintaining valve moves

up assisted by spring pressure to open the port connecting the crankcase to inlet manifold of the

exhauster, thereby evacuating the crankcase. When the vacuum in the crankcase reaches the

predetermined value as set, the same is maintained at that level by the piston moving down and cutting

off manifold connection.

GOVERNOR

The function of the air governor is to transmit main air reservoir pressure to the top of unloader plunger

as soon as the MR pressure reaches 10 kg/sq.cm and process of unloading starts. With the fall of

pressure to 8kg/sq cm the same supply is discontinued and existing pressure in the unloader valve is

vented out.

The NS-16 air governor consists of governor body in two pieces of bronze castings and a pipe bracket

with a number of air passages. It also incorporates (1) wire mesh filter (2) cut out cock (3) cut out

adjusting stem (4) cut out valve spring (5) cut out valve spring adjusting nut (6) cut in tail valve (7) cut

in valve (8) cut in valve adjusting stem (9) cut in valve spring (10) cut in valve adjusting nut.

When MR pressure gets access into the air governor through pipe A, it passes through the filter (1) to

passage B and then bifurcates in the pipe bracket. A part of this air passes through the passage C at

the bottom of the cut out valve. The other portion of the air passes through passage D and work on the

cut in tail valve.

Once the MR pressure reaches 10 kg/sq. cm, the pressure acting at the bottom of the cut out valve

overcomes the cut out valve spring tension and lifts the valve to get access to passage E. The air

pressure acting on cut in tail valve lifts the cut in valve thereby opening the passage from E to F which

leads to the top of the unloader plunger. At the same time the exhaust passage G of the casting is

blocked by the upper lips of cut in valve.


34/38

33

Once the MR pressure goes below 10kg/sq.cm.But remains above 8kg/sq.cm the cut out valve spring

forces the cut out valve to be seated and the passage from C to E is blocked. But the cut in valve is

still kept up with the help of pressure between 10kg/sq.cm to 8kg/sq.cm and the amount of air passing

through the cut in tail valve keeps on supplying air to the unloader valve top.

As soon as the MR pressure drops to 8kg/sq.cm, or below the cut in valve spring closes the valve and

thereby block the passage to F and no further air is supplied to the top of unloader. Further, whatever

air is there in the pipe line is exhausted as soon as the cut in tail valve upper lips move down opening

the connecting passage G to exhaust port.

INSTALLATION

For the installation of a new expressor or the overhauled expressor requires careful consideration since

proper alignment with the diesel engine is involved, in the alignment is not properly done, the

negligence of accuracy will cause unsatisfactory results and a sort life for the unit. Two condition may

arise under which expressor is replaced or reinstalled. In either case, perfect alignment be ensured.

First, if the diesel engine has been removed, which usually means that the expressor has also beenremoved. If the expressor only has been removed for replacement. In the first case it is very important

that alignment of expressor should not be started until the diesel engine, generator, and auxiliaries,

including fuel tanks, have been properly installed and secured in place and fuel, water and necessary

lubricating ail have been supplied.

The reason for this important procedure is that there is an arc in the locomotive frame which will level

off under the load of machinery. Therefore, the expressor should not be permanently place in position,

and aligned with the diesel engine until the locomotive body frame has leveled off and is approximately

straight.

Under either condition, as mentioned above, the alignment should checked wit an indicator in order to

obtain correct level. If possible, dial indicator should be used to check coupling alignment in all

directions to ensure that there is no misalignment. Under any condition, when the coupling between the

diesel engine compressors exhausted is parted, it is important to check that proper alignment is

obtained before the coupling is again tightened. Further, coupling must be inspected periodically for

tightness and mechanical defects and wear

MAINTAINENCE SCHEDULE

TRIP INSPECTION

Check oil level and top up, as required, with the diesel engine stopped.

Drain condensate from intercooler.

The recommended lubricants for the expressor SERVO PRESS 150 of IOC make.


35/38

34

MONTHLY INSPECTION (30 DAYS)

Clean the air intake filter of the compressor with engine stopped. Clean the strainer of the expressor

governor and the oil strainer of the expressor.

Check and record crankcase vacuum with diesel engine running.

Check the oil level.

Check whether there is any leakage of oil at the shaft seal.

QUATERLY INSPECTION (3 MONTHS)

Clean and inspect valve assembles, with the engine stopped. Renew gaskets between the wall

assembly and the cylinder head.

RECONDITION ON LOADERS.

Drain, clean and refill cranks case, check the split pin of the drive chain to ensure that it is well secured

and tight, before filling. Clean oil strainer. Check alignment of drive. Inspect the piping for tightness for

crank case check valve. Insure that the orifice is free from obstructions. Measure cranks case lube oil

pressure and record with engine running.

Check the temperature of cylinder heads. If it beyond the normal, find out the fault, with the engine

running and rectify it.

HALF YEARLY INSPECTION (WITH ENGINE RUNNING)

Clean and oil expressor governor. Ensure that the exhaust opening is free from dirt gum. Perform

orifice test. Use the 8.70 mm diameter orifice for the compressor and 12.7mm diameter orifice for the

exhauster portion. Maintain the capacity within the values shown in the graphs.

YEARLY INSPECTION (WITH ENGINE STOPPED 24 MONTHS)

Examine the oil pump, gears and the oil pump relief value of the expressor.

Examine intercooler safety valves and check their performance.

Decarbonizes the piston and the renew rings, if necessary.

TRIENNIAL INSPECTION

Carry out break- in test on the locomotive and then check the performance by orifice test if a test stand

is not available Drain and refill lubricating oil during the first fort nightly scheduled to remove all wear in

particles.


36/38

35

GENERAL

Check the condition of all other parts to avoid any OUT OF COURSE attention when expressor is

removed from the locomotive and dismantled for renewal of the face type carbon steels. Dismantle the

expressor if its leaks oil trough face type carbon seal due to its deterioration.

REPAIRS

RECONDITIONING CYLINDER AND PISTON WITHOUT REMOVING EXPRESSOR FROM

LOCOMOTIVE.

It certainly proves advantageous to do the repair work without removing the expressor from the

locomotive. For this the procedure adopted to secure maximum benefits greatly enhances the quality of

repair work done on the unit. The actual delivery of air found out by conducting the office test. The

damaged condition of the valves piston rings and cylinder indicate the deficiency in the actual delivery

of air as conducted by the orifice test. The damaged parts should be carefully examined and replaced.

Subsequent cleaning is necessary to decarbonize the valves and the cylinders heads and check again.

Even after observing the above procedures if the orifice test not satisfactory, the cylinders and pistons

should be removed for carefully analysis. The position of cylinder in the cranks case should be marked

per identification. The connecting rod bearing and wrist pin should be I good condition and the wrist pin

in their respective connecting rods, when checking the maximum & minimum clearance.

DISMENTALING EXPRESSOR FOR OVERHAUL

REMOVAL FROM LOCOMOTIVE

On doing major overhaul the seams used for alignment at the basement should be left as it is their

respective position so that it facilitates the reinstallation of the same expressor on the same locomotive

from which it has been removed. This saves times and effort spends for the correct alignment of the

unit with the basement in the locomotive.

REMOVAL OF COUPLING

The expressor exhauster bearing should be well protected any damages, while removing the coupling

from or refitting to crank shaft. The coupling hub should be heated quickly while using a gears puller to

facilitating the removal. Couplings are shrunk fit on the sharp. The clamping screws on the coupling

and remove for facilitating the removal of fan from the coupling half. Crank shaft locked nut is removed

from the sharp and a cooler is used to removed the coupling half. Now the other accessories such as

the intercooler, intake strainers, piping to the governor, oil gauge, and exhauster many folds and side

covers are removed.

The cup nut, spring shims and the piston of oil pressure indicator are also removed.

OIL PUMP DISMENTALING

For dismantling the oil pump assembly.


37/38

36

1. Removed the tube connecting the oil pressure indicator to the oil pump body.

2. Loosen the lock nut and set is screws which holds oil strainer body in place, then removed the

oil or strainer body and then remove the sprocket screw and stay pin, from the oil pump body.

Remove the strainer.

3. Take out the master link to remove the derive chain.

4. The lock wire and torque screws and removed to remove the oil pump body.

5. The lock wire and the two cap screws are removed to remove the oil pump bearing cap at crank

shaft end.

6. Remove the crank shaft sprocket and after removing the lock ire to shoulder screw which holds

it in place.

7. The dry key from the crank shaft is also removed.

REMOVAL OF OTHER PARTS

1. Remove the cylinder heads, cylinder connecting rods, piston, and crankshaft.

2. Place the crank case in position so that the axis of the crank shaft is vertical and men bearing

facing upwards, when dismantling the cranks assembly. Wild dismantling cranks all possible

care is to be taken avoid damaged to the ball bearings.

3. The end cover which is secure to the crank case by means of cap screw is removed. Three

inches UNC screws should be inserted to the tapped holes in the end cover and gradually

tighten all the screws simultaneously by equal amounts. The end cover is thus raised gradually,

until it is possible to apply a gears pulls to the edge of the housing. Then use a puller and

removed the end cover.

4. In applying the puller care should be taken so the crank shaft center is not damaged. For this a

tick metal disc can use between the gears puller screws and the crank shaft.

5. A lifting device is necessary for removing the crank shaft. This lifting device consists of a

threaded portion to which is welded a V shaped loop of sufficient size to permit the insertion of

the hook of the lifting equipment. Apply the nut to the end of the crank shaft knock its upper end

back and forth at right angles to its axis. The shaft is to be removed without causing damaged

to the bearings for this it should be checked the lifting force is in line with the crank shaft to

prevent wedging acting between the bearing and crank shaft.

GENERAL REPAIRS

Inspection has to be carried out and for this all parts should be thoroughly, the drilled all passages, oil

ling should be free from any obstruction and should be checked for any damages. If there are any

damages in crank shaft it should be replaced.


38/38

OBJECTIVES

To study overhauling practices of expressor.

To study the problem of loading/unloading on locos fitted with air dryers and suggest

solutions after searching about latest maintenance practices followed in other countries.

To study Cases of fire in expressers and suggest preventive measures to arrest fire

cases in espressers

To study overhauling practices of expressor.

Project Study

tkd final report (expressors)

Documents