Air Compressors In Diesel Locomotives 2623n

CHAPTER 1 INTRODUCTION 1.1 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 2012, IR carried over 8,900 million engers’ annually or more than 24 million engers daily (roughly half of which were suburban engers) and 2.8 million tons of freight daily.

In

2012–2013

Indian

Railways

had

revenues

of 1119848.9

million (US$19 billion) which consists of 696759.7 million (US$12 billion) from freight and 286455.2 million (US$4.8 billion) from engers tickets. Railways were first introduced to India in 1853 from Bombay to Thane. In 1951 the systems were nationalised as one unit, the Indian Railways, becoming one

of

the

largest

distance and suburban

networks rail

in

the

system on

world.

IR

operates

a multi-gauge net

both long work

of broad, metre and narrow gauges. It also owns locomotive and coach production facilities at several places in India and are assigned codes identifying their gauge, kind of power and type of operation. Its operations cover twenty nine states and seven

union

territories and

also

provide

limited

international

services

to Nepal, Bangladesh and Pakistan. 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 enger 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. Since 1960, almost all electrified sections on IR use 25,000 Volt AC traction through overhead catenary delivery. 1

1.2 Indian Railways Overview:

"Lifeline of the Nation" Type

Public Sector Undertaking

Industry

Railways

Founded

April 16, 1853 (161 years ago)

Headquarters

New Delhi, India

Area served

India

Services

enger Railways freight services, Parcel carrier, Catering and Tourism Services.

Revenue

1256.8 billion (US$21 billion) (2012–13)

Net Income

104.1 billion (US$1.7 billion) (2012–13)

Owner(s)

Government of India (100%)

Employees

1.3 million (2012)

Parent

Ministry of Railways through Railway Board (India)

Divisions

17 Railway Zones 2

Indian Railways Reporting Mark

IR

Locate

India

Dates of operation

16 April 1853–Present

Track Gauge

1,676 mm (5 ft. 6 in) 1,000 mm (3 ft. 3 3⁄8 in) 762 mm (2 ft. 6 in) 610 mm (2 ft.)

Length

65,000 kilometres (40,000 mi)

Headquarters

New Delhi, India

Electrification

23,541 kilometres (14,628 mi)

Fig.1.1: Diesel Locomotive Engine

3

1.3 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 kilometre 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. This route was officially opened on 7 March 1870 and it was part of the inspiration for French writer Jules Verne's book Around the World in Eighty Days. At the opening ceremony, the 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”. By 1875, about £95 million were invested by British companies in India guaranteed railways. By 1880 the network had a route mileage of about 14,500 km (9,000 mi), mostly radiating inward from the three major port cities of Bombay, Madras and Calcutta. By 1895, India had started building its own locomotives, and in 1896, sent engineers and locomotives to help build the Uganda Railways. In 1900, the GIPR became a government owned company. The network spread to the modern day states of Ahom Kingdom, Rajputhana and Madras Presidency and soon various autonomous kingdoms began to have their own rail systems. In 1905, an early Railway Board was constituted, but the powers were formally vested under Lord Curzon. It served under the Department of Commerce and Industry and had a government railway official serving as chairman, and a railway manager from England and an agent of one of the company railways as the other two . For the first time in its history, the Railways began to make a profit.

4

In 1907 almost all the rail companies were taken over by the government. The following year, the first electric locomotive made its appearance. With the arrival of World War I, the railways were used to meet the needs of the British outside India. With the end of the war, the railways were in a state of disrepair and collapse. 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. The period between 1920 and 1929, was a period of economic boom; there were 41,000 mi (66,000 km) of railway lines serving the country; the railways represented a capital value of some 687 million sterling; and they carried over 620 million engers and approximately 90 million tons of goods each year. Following the Great Depression, the railways suffered economically for the next eight years. The Second World War severely crippled the railways. Starting 1939, about 40% of the rolling stock including locomotives and coaches was taken to the Middle East, the railways workshops were converted to ammunitions workshops and many railway tracks were dismantled to help the Allies in the war. By 1946, all rail systems had been taken over by the government.

5

Production Units Name

Abbr.

Year Established

Location

Bharat Wagon and Engineering Muzaffarpur

BWEL

1978

Muzaffarpur

JLW

1862

Jamalpur

GOC

1928

Trichy

Diesel-electric Locomotives

CLW

1947

Chittaranjan, Asansol

Electric Locomotives

DLW

1961

Varanasi

Diesel Locomotives

DMW

1981

Patiala

Diesel-electric Locomotives

ICF

1952

Chennai

RCF

1986

Kapurthala

RSK

1988

Gwalior

RWF

1984

Bangalore

RWF

2012

Chhapra

RCF

2012

Raebareli

Jamalpur Locomotive Workshop Golden Rock Railway Workshop Chittaranjan Locomotive Works Diesel Locomotive Works Diesel-Loco Modernisation Works Integral Coach Factory Rail Coach Factory Rail Spring Karkhana Rail Wheel Factory Rail Wheel Factory Rail Coach Factory, Raebareli

Table no.1.1: Production Units

6

Main products enger Coaches (manufacturing + maintenance). Diesel/Electric Loco maintenance.

enger coaches enger coaches enger coach springs Railway wheels and axles Railway wheels enger coaches

1.4 ORGANISATIONAL STRUCTURE & STAFF STRENGTH: Railway zones Indian Railways is divided into several zones, which are further sub-divided into divisions. The number of zones in Indian Railways increased from six to eight in 1951, nine in 1952 and sixteen in 2003 and now seventeen. Each zonal railway is made up of a certain number of divisions, each having a divisional headquarters. There are a total of sixty-eight divisions. Each of the seventeen zones is headed by a general manager who reports directly to the Railway Board. The zones are further divided into divisions under the control of divisional railway managers (DRM). The divisional officers of engineering, mechanical, electrical, signal and telecommunication, s, personnel, operating, commercial, security and safety branches report to the respective Divisional Manager and are in charge of operation and maintenance of assets. Further down the hierarchy tree are the station masters who control individual stations and the train movement through the track territory under their stations istration. Zonal Railway details

Sl. No

Name

Date Established

Route km

Head quarts

1

Central

05-Nov-51

3905

Mumbai

2

Western

05-Nov-51

6182

Mumbai

3

Southern

14-Apr-51

5098

Chennai

4

Eastern

14-Apr-52

2414

Kolkata

5

Northern

14-Apr-52

6968

Delhi

6

North Eastern

14-Apr-52

3667

Gorakhpur

7

Divisions Mumbai, Bhusawal, Pune, Sholapur and Nagpur Mumbai Central, Ratlam, Ahmedabad, Rajkot, Bhavnagar Gandhidham Vadodara Chennai, Tiruchirappalli, Madurai and Salem, Palakkad, Thiruvananthapuram Howrah, Sealdah, Asansol and Malda Delhi, Ambala, Firozpur, Lucknow,Moradabad and Udhampur Izzatnagar, Lucknow and Varanasi

7

South Eastern

1955

2631

Kolkata

8

South Central

02-Oct-66

5951

Secundrabad

9

Northeast Frontier

15-Jan-58

3907

Guwahati

10

East Central

01-Oct-02

3628

Hajipur

01-Oct-02

5459

Jaipur

01-Apr-03

2677

Bhubaneswar

01-Apr-03

3151

Allahabad

Allahabad, Agra and Jhansi

01-Apr-03

2447

Bilaspur

Bilaspur, Raipur and Nagpur

11 12 13 14

North Western East Coast North Central South East Central

Adra, Chakradharpur, Kharagpur and Ranchi Vijayawada, Secunderabad, Guntakal, Guntur, Hyderabad and Nanded Alipurduar, Katihar, silchar Rangia,Lumding and Tinsukia Danapur, Dhanbad, Mughasarai,Samastipur and Sonpur Jaipur, Ajmer, Bikaner and Jodhpur KhurdaRoad, Sambalpur and Waltair

15

South Western

01-Apr-03

3177

Hubli

Hubli , Bangalore, Mangalore, Kozhikode and Mysore

16

West Central

01-Apr-03

2965

Jabalpur

Jabalpur, Bhopal and Kota

17

Kolkata Metro Railway

Kolkata

Kolkata metropolitan area, South 24Parganas and North 24 Parganas

29-Dec-10

28

Total

64255

Table no.1.2: Zonal Railway Details



Staff in Diesel loco shed, Kazipet 8

Kazipet has a sanctioned strength of 1313 against which 1210 persons are on roll. There are 9 posts of officer in the shed. The shed is headed by the Sr. DME who is assisted by 2 Sr. scale & 6 Jr. Scale officers. The laboratories are looked after by an ACMT and the attached stores depot by an AMM. The training school & simulator centre have been entrusted to a separate Assistant Officer. These officer also report to the Sr. DME.

Fig.1.2: Organisational Structure of Diesel Loco Shed

1.5 SHED LAYOUT:

9

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 was one old steam shed. This shed had a capacity for berthing 4 locomotives. This shed was used for light repairs only. Now days, a new construction is being on for new locos of make WDP4 locomotives.

Fig.1.3: Layout Plan of Diesel Loco Shed

10

Fig.1.4: Top View of Layout Plan of Diesel Loco Shed

11

CHAPTER 2 Air Compressor

2.1 Introduction:

In this chapter the diagram of the air compressor and design aspect of independent parts of the air compressors are considered. Diagram is shown in figure 2.1:

Fig.2.1: Reciprocating air compressor in Locomotives An air compressor is a device that converts power (usually from an electric motor, a diesel engine or a gasoline engine) into kinetic energy by compressing and pressurizing air, which, on command, can be released in quick bursts. There are numerous methods of air compression, divided into either positivedisplacement or negative-displacement types.

12

2.2 Types of Air Compressor: 2.2.1 According to the Design and Principle of Operation: 1. Reciprocating Compressor 2. Rotary Screw Compressor 3. Turbo Compressor

1. Reciprocating Compressor: A reciprocating

compressor or

piston compressor is

a

positive-

displacement compressor that uses pistons driven by a crankshaft to deliver gases at high pressure. The intake gas enters the suction manifold, then flows into the compression cylinder where it gets compressed by a piston driven in a reciprocating motion via a crankshaft, and is then discharged. Applications include oil refineries, gas pipelines, chemical plants, natural gas processing plants and in locomotives. The heat exchangers that are used in a normal piston compressor are removed as the heat is removed in the cylinder itself where it is generated. Almost 100% of the energy going into the process is being used with little energy wasted as reject heat.

Fig.2.2: Sectional View of Reciprocating Air Compressor 13

2. Rotary Screw Compressor: A rotary screw compressor is a type of gas compressor which uses a rotary type positive displacement mechanism. They are commonly used to replace piston compressor where large volumes of high pressure air are needed, either for large industrial applications or to operate high-power air tools such as jackhammers. The gas compression process of a rotary screw is a continuous sweeping motion, so there is very little pulsation or surging of flow, as occurs with piston compressors.

Fig.2.3: Rotary Screw Compressor

Fig.2.4: Sectional view of Rotary Screw Compressor

14

3. Turbo Compressor: Turbocharger compressors are generally centrifugal compressors consisting of three essential components: compressor wheel, diff, and housing. With the rotational speed of the wheel, air is drawn in axially, accelerated to high velocity and then expelled in a radial direction.

Fig.2.5: Turbo Compressor 2.2.2 Positive Displacement Compressor: Positive-displacement air compressors work by forcing air into a chamber whose volume is decreased to compress the air. Piston-type air compressors use this principle by pumping air into an air chamber through the use of the constant motion of pistons. They use one-way valves to guide air into a chamber, where the air is compressed. Rotary screw compressors also use positive-displacement compression by matching two helical screws that, when turned, guide air into a chamber, whose volume is decreased as the screws turn. Vane compressors use a slotted rotor with varied blade placement to guide air into a chamber and compress the volume. A type of compressor that delivers a fixed volume of air at high pressures. Common types of positive displacement compressors include piston compressors and rotary screw compressors.

15

Fig.2.6: Positive Displacement Compressor 2.2.3 Non Positive Displacement Compressor: Non positive displacement air compressors include centrifugal compressors. These use centrifugal force generated by a spinning impeller to accelerate and then decelerate captured air, which pressurizes it.

Fig.2.7: Non positive Displacement Compressor

16

2.3 Description Air Compressor: AIR

COMPRESSOR

MODELS

WLN

AND

WLG

DESCRIPTION The WLN and WLG model air compressors are water cooled two stage air compressors. Each compressor has its own oil pump and pressure lubricating system. Domestic models are equipped with a deep sump oil pan. Export models are equipped with a shallow sump oil pan. The WLN (formerly WBO) compressor has two low pressure and one high pressure cylinders and the WLG (formerly WBG) compressor has four low pressure and two high pressure cylinders. The low pressure cylinders are set at an angle to the vertical high pressure cylinder position. The pistons of the high and low pressure cylinders are all driven by common shafts.

Fig.2.8: Side View of Air Compressor in Locomotives

17

CHAPTER 3 Parts of the Compressor In this chapter we will discuss about the different parts of the compressor. The following are the lists of the parts: 1.Crank Case Body 2.Breather Valve 3.Cylinder or liner 4.Crank Shaft 5.Piston with connecting rod 6.Cylinder head with Valves 7.Lube Oil Pump 8.Inter Coolers 9.After Coolers 10.Safety Valve 11.Drain Valve 12.EPG Governor 13.Solenoid valve 14.Indicator Valve 15.Main Reservoir Tank (MR Tank)

18

3.1 Crank Case Body: The crankcase was employed as a sump for the lube oil, Which houses 21 litres of lube oil, The side cover mounted on the crankcase Is provided with' an oil filling pipe which prevents over filling of oil. This pipe is closed with a threaded type cap and float type oil level indicator for indicating the level of oil in the crank case. The crankcase has four mounting holes for mounting the compressor in the locomotive. The lube oil pump can be dismantled from the crankcase by removing the mounting pump. A breather valve is provided at the top of the crankcase, which keeps the crankcase in a partial vacuum condition. Oil seal were provided on both side of crankcase along the crankshaft axis, which prevents oil leaks and dust entering the crankcase.

Fig.3.1: Crank Case Body

19

3.2 Breather Valve: WLN compressors are equipped with a crankcase breather which permits a partial vacuum in the compressor crankcase. To accomplish this, the breather acts as a check valve. When pressure builds up in the crankcase as the pistons move down, the breather valve opens. As the pistons start up, the breather valve closes, preventing the ission of air into the crankcase

. Fig.3.2: Breather Valve

20

3.3 Cylinder or Liner: This compressor has two 196,875 mm diameters Low Pressure Cylinders and one 139.7tiim diameter high Pressure Cylinder, Cylinders are made up of Grey iron Castings with hexagonal fins for better cooling.

Fig.3.3: Cylinders

21

3.4 Crank Shaft: This converts rotary motion into reciprocating motion. It transfers power form the engine to the piston.

Fig.3.4: Crank Shaft

3.5 Piston with Connecting Rod: Piston is used to compress the air inside the cylinder. The piston has four rings, two rings are at the top which are known as the Compression Rings. The other two are known as oil scrapper rings. The oil scrapper rings are used to scrap the oil from the cylinder walls. The Following Figure will illustrate it.

22

Fig.3.5: Piston

Fig.3.6: Piston Rings

23

Connecting Rod: In a reciprocating piston Engine, the connecting rod or conrod connects the piston to the crank or crank shaft. Together with the crank, they form a simple mechanism that converts reciprocating motion into rotating motion. Connecting rods may also convert rotating motion into reciprocating motion. Historically, before the development of engines, they were first used in this way. As a connecting rod is rigid, it may transmit either a push or a pull and so the rod may rotate the crank through both halves of a revolution, i.e. piston pushing and piston pulling. Earlier mechanisms, such as chains, could only pull. In a few twostroke engines, the connecting rod is only required to push.

Fig.3.7: Connecting Rod

24

3.6 Cylinder Head with Valves: This Compressor Is equipped with three cylinder heads; the valves are Individual disc type, loaded with springs, operated due to the differential pressure between the upstream and downstream pressure. As the name indicates that it is located at the top or at the head of the cylinder. It has two valves in the head they are 1. Inlet or Suction Valve and 2. Discharge Valve 3.6.1 Inlet or Suction Valve: Inlet valves are located at the suction side on the cylinder head. The inlet valve is as shown in the figure below

Fig.3.8: Inlet Valves

3.6.2 Discharge Valve: 25

Discharge valve is located on the discharge side of the cylinder head. The Discharge valve is as shown in the figure.

Fig.3.9: Discharge Valve Working Principle of the Valves: As we see from the figure, in the first stage i.e., low pressure side, when the piston moves from the Top Dead Centre (TDC) to Bottom Dead Centre (BDC) vacuum is created in the cylinder due to this vacuum, the plate on the valve compresses the spring which is located below the plate. Due to this spring tension the plate comes downwards and then the air from the air strainer enters into the cylinder and then when the piston moves from the BDC to TDC air which is entered into the cylinder is compressed in the second stage i.e., high pressure side. After the compression the valve plate tries to compress the spring which is on the top of the plate and then the compressed air is send to after cooler and then to the MR tank. Following figure shows the exact working principle of the valves.

26

Fig.3.10: Working Principle of the Valves 

Cylinder Head with the Valves: The following figure shows the figure of the Cylinder Head with the

Valves.

Fig.3.11: Cylinder with the Valves

3.7

Lube

Oil

Pump: The

oil

pump circulates the oil under pressure. Drive is taken from the crankshaft. By means of a Set of gears with an Idler, to pump the oil through the system. A primary oil filter which faces the inner side of the crankcase bottom filters the oil to prevent the Ingress of external agents

27

like dust and other solid particles from entering into the pump and the lubricating system. The filtered oil is ed through the groove to the distributing ring. Through the distributing ring, the lubricating oil flows to each crank pin in the crankshaft through the oil holes drilled in It, The oil lubricates the Inner bearings of the connecting rods through the groove provided and the needle roller bearing and gudgeon pin at small end through the hole drilled in the connecting rods. A relief valve fitted on the body of the oil pump maintains the oil pressure between 2.2 to 3.5 kgf/cm2. It can be adjusted to the desired oil pressure. In case the oil line pressure exceeds. The oil relief valve opens and allows the oil out the pump, thus maintaining the set pressure. An oil pressure Indicator valve, mounted on the side cover of crankcase helps to ensure the line pressure of the oil system. Recommended oil pressure is minimum 2.2 kg/ cm2 at Idle and 3.5 kg/cm2 at full speed. Oil seals fixed at the outer position of the two bearings prevent the oil leakage over the shaft and the atmospheric air entering into the crankcase. Oil level can be checked visibly, and by the dipstick through the transparent oil level indicator, fitted on the side cover of the crankcase, the breather fitted on the crankcase maintains partial vacuum inside the crankcase which ensures better lubrication. The oil pump relief valve & oil pressure indicator respectively. Oil will overflow while filling when the maximum level is reached.

Fig.3.12: Lube Oil Pump

3.8 Intercooler and After- cooler: The Intercooler reduces the temperature of the compressed air leaving the first stage prior to entering the second stage in order to improve the overall

28

thermodynamic efficiency of the system. The air from atmosphere is forced to flow configuration to reduce the temperature of the compressed air. The inlet-cooler contains ages for engine cooling water and for air from the low pressure cylinders. It acts to remove heat from the compressed air, making it denser, and thereby improving the efficiency of the high pressure cylinder(s). The basic intercooler has one water inlet and one water outlet, but some intercoolers (two) have one water inlets and two outlets to obtain parallel flows and more efficient cooling of the air- A two- intercooler is required for operating speeds of 950 RPM or greater. Air flow is the same through each typ.3 of intercooler.

Fig.3.13: Inter - Cooler

3.9 Relief and Indicator Valves:

29

These valves works on the same principle when the relief valve fitted on the body of the oil pump maintains the oil pressure between 2.2to 3.5 kgf/cm2. It can be adjusted to the desired oil pressure. In case the oil line pressure exceeds. The oil relief valve opens and allows the oil out the pump, thus maintaining the set pressure. An oil pressure Indicator valve, mounted on the side cover of crankcase helps to ensure the line pressure of the oil system. Recommended oil pressure is minimum 2.2 kg/ cm2 at Idle and 3.5 kg/cm2 at full speed. Oil seals fixed at the outer position of the two bearings prevent the oil leakage over the shaft and the atmospheric air entering into the crankcase. Oil level can be checked visibly, and by the dipstick through the transparent oil level indicator, fitted on the side cover of the crankcase, the breather fitted on the crankcase maintains partial vacuum inside the crankcase which ensures better lubrication. The oil pump relief valve & oil pressure indicator respectively. Oil will overflow while filling when the maximum level is reached.

Fig.3.14: Relief and Indicator Valve

3.10 Main Reservoir Tank (MR Tank): 30

It is the main component of the air compressor in locomotives which stores the compressed air in the cylindrical vessel of having pressure in the range of 8-10 kgf/cm2. The air from the after cooler directly enters into the MR tank. If the pressure reaches the maximum range then the cylinder will damage due to fatigue.

Fig.3.15: MR Tank

CHAPTER 4 31

WORKING PRINCIPLE

4.1 Working principle of air compressor: 'Before AIR enters the compressor the air is cleaned by age through a drytype air filter. On single filter units the filter is mounted on the air inlet manifold. On dual filter units the filters are mounted directly onto each of the two low pressure cylinder heads- Dual lifters are recommended for optimum compressor performance. Air at atmospheric pressure is drawn in through the litres and intake valves into the low pressure cylinders during the downward strokes of the pistons- As the air is compressed on the upward stroke, the intake valve is closed and the air at higher pressure is forced through the discharge valve into the intercooler. Air leaves the intercooler, entering the high pressure cylinder through its intake valve. As the high pressure piston moves upward, it compresses the air 10 a higher pressure, forcing it out through the discharge valve and connecting piping to the main air reservoir.

Fig.4.1: Working Principle of Air Compressor

4.2 Unloaded Principle: 32

When the MAIN RESERVOIR reaches the recommended pressure, the compressor activates the EPG ( ELECTRO PNEUMATIC GOVERNOR) when this get activated the compressor governor senses the pressure in the MR Tank and sends the information to solenoid switch which help to control the it air to the unloaded assembly, i.e. cutting out the compressor action by holding the intake valve open. Here the air from MR tank divides into two ways one is to compressor and the other one to relief valve. When reservoir reached the safe pressure the pressure falls off. The air operating the unloader is cut off, the intake valve is released, and the compressor resumes normal pumping.

Fig.4.2: Unloader Principle

CHAPTER 5 33

AIR INTAKE AND COOLING SYSTEM

5.1 AIR INTAKE SYSTEM: 'Before AIR enters the compressor the air is cleaned by age through a drytype air filter. On single filter units the filter is mounted on the air inlet manifold. On dual filter units the filters are mounted directly onto each of the two low pressure cylinder heads- Dual lifters are recommended for optimum compressor performance. Air at atmospheric pressure is drawn in through the filters and intake valves into the low pressure cylinders during the downward strokes of the pistons- As the air is compressed on the upward stroke, the intake valve is closed and the air at higher pressure is forced through the discharge valve into the intercooler. Air leaves the intercooler, entering the high pressure cylinder through its intake valve. As the high pressure piston moves upward, it compresses the air 10 a higher pressure, forcing it out through the discharge valve and connecting piping to the main air reservoir.

Fig.5.1: Air Intake system

5.2 Cooling System: 34

To cool the compressor the water pump circulates the water to low pressure cylinders of both sides of compressor and to high pressure cylinder. While water pumping to LP cylinder an intermediate connection will be there to intercooler. Water which es through intercooler helps to cool the high pressurized air. In LP cylinder the water enters to LP Liners to head of the cylinder and in the same the water enters to HP cylinder. The water in compressor at last is collected at HP cylinder head from there it flows to oil cooler to radiator.

Fig.5.2: Radiator

CHAPTER 6 35

LUBRICATION OF COMPRESSOR

Lubrication of Compressor: The compressor lubricating system is piloted by the gear drive Oil pump. The oil pump circulates the oil under pressure. Drive is taken from the crankshaft. By means of a Set of gears with an Idler, to pump the oil through the system. A primary oil filter which faces the inner side of the crankcase bottom filters the oil to prevent the Ingress of external agents like dust and other solid particles from entering into the pump and the lubricating system. The filtered oil is ed through the groove to the distributing ring. Through the distributing ring, the lubricating oil flows to each crank pin in the crankshaft through the oil holes drilled in It, The oil lubricates the Inner bearings of the connecting rods through the groove provided and the needle roller bearing and gudgeon pin at small end through the hole drilled in the connecting rods. A relief valve fitted on the body of the oil pump maintains the oil pressure between 2.2 to 3.5 kgf/cm2. It can be adjusted to the desired oil pressure. In case the oil line pressure exceeds. The oil relief valve opens and allows the oil out the pump, thus maintaining the set pressure. An oil pressure Indicator valve, mounted on the side cover of crankcase helps to ensure the line pressure of the oil system. Recommended oil pressure is minimum 2.2 kg/ cm2 at Idle and 3.5 kg/cm2 at full speed. Oil seals fixed at the outer position of the two bearings prevent the oil leakage over the shaft and the atmospheric air entering into the crankcase. Oil level can be checked visibly, and by the dipstick through the transparent oil level indicator, fitted on the side cover of the crankcase, the breather fitted on the crankcase maintains partial vacuum inside the crankcase which ensures better lubrication. The oil pump relief valve & oil pressure indicator respectively. Oil will overflow while filling when the maximum level is reached.

36

Fig.6.1 Lube Oil Flow Path

37

CHAPTER 7 AIR COMPRESSOR MAINTANCE AND SPECIFICATIONS 7.1 Air Compressor Maintance: The compressor oil level should be checked regularly using the dipstick, and the oil level should be kept at the full mark. The compressor oil and compressor oil filter should be changed at the scheduled maintenance intervals. The compressor air filters should be changed out at the scheduled maintenance 1intervals. Remove the filters by first removing the nuts attached to the clamps on the filter housing. Swing the clamps to the side and remove the retainer screen. The filter housing and screen should be cleaned whenever the filter elements are changed. When the applications of test gauges are required for Maintenance, ensure that the gauges are removed and the proper size plug is inserted and tightened before returning the locomotive to service. Air compressor change out and overhaul should be done at the scheduled maintenance intervals. For detailed rebuild instructions see the appropriate vendors’ instructions.

38

Fig.7.1: Air Compressor Maintance

7.2 AIR COMPRESSOR CONTROL: The standard air compressor on a GT46PAC locomotive is coupled directly to the diesel engine through a driveshaft and when the engine is running, the air compressor is being driven. Therefore an unloader assembly, mounted on the compressor, is required to control when the compressor is actually pumping air.

39

The intake or suction valves of the compressor contain unloaders that block the valve open when pneumatically activated. With the intake valves blocked open the compressor is incapable of compressing, whether it is rotated or not. These unloaders are controlled pneumatically, through the unloader magnet valve. This valve is called the MV-CC, or Magnet Valve Compressor Control. The locomotive computer, the EM2000, controls the MV-CC in turn. When the locomotive is started, the computer picks up the MV-CC, allowing main reservoir air through to activate the unloaders. When the computer, monitoring 11main reservoir pressure, notes that the pressure is below the required pre-programmed maximum pressure it drops out the MV-CC. This releases the unloaders causing the compressor to load.

Fig.7.2: Air Compressor

40

7.3 Specifications of Air Compressor

Fig.7.3: Specifications of RR 66 101 W Compressor

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CHAPTER 8 CONCLUSION

The compressor is located at the free end of the engine block and driven through the extension shaft attached to the engine crank -shaft. Compressor is a combined unit of Crank case, cylinder, piston and the inlet and the exhaust valve. The main function of compressor unit is to create air pressure in main reservoir of locomotive up to 10kg/cm2. Atmospheric air is drown into the compressor LP cylinder through the open inlet valves during suction stroke and same air is discharged to HP cylinder through discharge valves and delivery pipe. The HP cylinder compresses the air at high pressure and discharges it in main reservoir of locomotive for the use of brake system.

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