INTRODUCTION
The B.E.S.T Company had been established in England under the companies Act of the country. Its registered office was in London and its board of management met here. As a result the company had to pay a similar tax in this country too.This double taxation hit the shareholders in India rather badly. The Directors of the company in London, drawing attention of the chancellor of the Exchequer to this in 1909, pointed out likelihood of the Indian shareholder insisting on shifting the head office of the company to Mumbai. Nothing came of it. And later the Indian shareholder did insist on the winding up of the B.E.S.T company in London.
The first World war started about same time The rates of the British income tax went up sharply, as did of those of other taxes. This made the double taxation even more unbearable to the Indian shareholders. The company’s directors made another fervent plea to the chancellor of the Exchequer stating that there would soon be no alternative to closing down its London office. They further argued that the company made all its purchase in England, thus contributing handsomely to the country’s treasury. Nothing came of this to.
REORGANISATION OF THE B.E.S.T COMPANY
As a result of handling entire management of the company from Mumbai the Board of directors planned to convert the company’s capital in pound sterling into it’s corresponding/value in rupees; but under the company’s law the only way of achieving it was by winding up the old company was registered under English companies Act, the law required that the shareholders meet in London in order to wind it up. Thus they met in London n 9th June 1920, and passed resolution to wind up its affair s. The shareholder in Mumbai met on 30th June 1920, and approved the resolution passed at London meeting.
The newly established B.E.S.T company had total capital of Rs.3 core and 90 lakhs, divided into 6 lakhs ordinary shares of 50 rupees each, and 1 lakh 80 thousand preference shares of the same value .
The new company got the formal approval of the Municipality. During the next twenty-seven years it underwent no fundamental changes. It is just story of expansion. The city kept growing, and the company’s activities kept pace with it .as was inevitable. The growth of the company in fact provided a fairly accurate measure of the growth of the city, so closely linked they used to be. So they are even today. The B.E.S.T company came into existence on 7thAugust 1905;it was dissolved on 6th August 1947,to make room for the B.E.S.T Undertaking.
TRANSPORTATION
The origin of the Kingsway workshop go back to the Colaba causeway workshop was opened there in 1886.People living in surrounding area are complained of nuisance from the workshop in 1910 and company (by now B.E.S.T company) decided to shift the workshop to a convenient spot in the north city. Accordingly, in June 1915 land was acquired from the improvement trust at Kingsway, between Dadar andMatunga, on a 999-year lease. A workshop was soon erected on the plot.
The workshop undertook the repairs of both the coachwork and electrical machinery of trams. It was equipped with all the necessary machines, such as heavy duty shaping machine,a tyre cutting lathe,a tyre-heating furnace, an armature winding plant, a coil testing machine,etc. The work was carried out in section such as truck shop the paint shop, the machine shop,etc.
When bus were introduced in 1926, a bus workshop was opened in Colaba. Transportation engineering was now divided into separate sections for trams and buses. When the Colaba workshop began to prove inadequate to the needs of buses, another bus workshop was opened at Dadar near the tram workshop .This workshop had various sections for repairs of to chassis (base frame, engine, and wheels),body and ancillaries, and seats and windows,apaint shop, a machine shop, an electrical section, a major/minor unit section, calibration and lubrication, a tyre section,etc.
After 1947 the workshop space was found to inadequate with the exapation of the bus service. In 1950 further land was acquired next to the Kingsway tram workshop and new workshop was planned to maintain a fleet of 600 buses.
When trams were abolished in 1964, the tram shed in Kingsway tram workshop were taken over for the expansion of bus workshop. This was usefultemporary expedient; but these sheds had been specially designed for trams and did not permit a scientifically planned expansion of the bus workshop.
| YEAR | LANDMARKS |
| 1873 | Bombay Tramway Co. Ltd. started |
| 1874 | Horse-drawn Trams Introduced. |
| 1905 | Bombay Electric Supply & Tramway Co. Ltd. started |
| 1907 | First Tram ran on Electricity. |
| 1909 | Beaver Single Decker Cars started. |
| 1912 | S.T.T Cars Started. |
| 1920 | Double-decker Tram introduced. |
| 1967 | Articulated(Trailer) buses came into operation. |
| 1972 | Silver Jubilee of Muncipalisation. Tata single Decker buses introduced. |
| 1990 | Free travel Facility to freedom fighter residing in Mumbai, introduced. |
| 1992 | Automotive Bus washing machine installed at depots. |
| 1994 | Concessional tickets facility extended to student studying in Junior Colleges. Operation extended to thane by extending Route 30Ltd |
| 1996 | Single decker Articulated Vestibule buses Introduced. |
| 1997 | Environment Friendly Buses fitted with compressed natural Gas engine Introduced. Introduction of monthly bus scheme of selected routes. Luxury Bus introduced. |
| 1999 | New Mulund depot were commissioned. |
| 2000 | Monthly bus pass scheme Discontinued All luxury buses discontinued from 1/12/2000 |
| 2007 2008 2009 | Exclusive Bus lane for BEST buses from Mumbai CST to mantralaya(approx3.5km) CNG buses with Electronic Display were introduced |
| 2010 | Euro3 CNG King long &Ashok Leyland AC buses were introduced |
| 2011 | New Volvo AC buses introduced to Oshiwara Depot Euro4 CNG TATA AC buses going to launched |
TECHNICAL TRAINING CENTRE
TECHNICAL TRAINING CENTRE
Technical training Centre located at Wadala depot. This training Centre play vital role in skill &knowledge of technical personnel.
Training of Trade apprentices:
TTC CLASSROOM
Following are main activities of Technical training Centre:
a) To implement requirements under apprentices act 1961 including recruitment of trade apprentices and to imparts training as per syllabus of the different trade under the directives of the state apprenticeship adviser, government of Maharashtra.
b) To maintain records of trade apprentices, regulate their training programs and prepare apprentices for National Council of vocational training New Delhi examination. Apprentice who stand first, in their respective trades at their local trade examination Centre are considered for employment on priority basis, at present there are 600 apprentices taking training at TTC, Wadala.
Apprentices are appointed under the apprenticeship under the act 1961 in designated trades
a) Mech.MV
b) Fitter BB
c) MV BB
d)Turner
e)Welder
g)R&A Mechanic
h)Cable Jointer
The training Centre is headed by one executive engineer and is assisted by one assistant engineer,2sub engineer,6 general office foreman, 9 assisted foreman(instructor), 6-Electrical staff.
Training of probationary Engineer Diploma/Graduate Trainees:
The training is conducted for prob. Engineers (graduate) to enable them to man operations and maintain bus fleet in future –who are absorbed in management cadre.
Technician apprentices and sandwich course students in diploma as well as degree category are imparted training under the apprenticeship act1973. Local engineering colleges and government authorities sponsor these candidates.
Arranging seminars, training programs lectures:
Seminars, training programs, lectures for benefits of officer and staff are arranged with the help of OE of manufacture, firms engaged in in manufacturing products useful for undertaking Training cum educational visit to various exhibitions and industry are arranged. Training Centre also takes parts in various exhibitions ,and other technical exhibitions.
Training facilities/equipments:
Technical training Centre well equipped with TV, VCR,Projector, cut and working model of engine, electrical units, chassis fuel injection pump, gear box etc. It is well equipped with machine shop having lathe machine, drilling machine, milling machine; fly press, tin cutter, Welding machine, shaping machines.
Chapter-2
INTRODUCTION TO DEPARTMENTS
1. R&M CHASSIS SECTION
2. ENGINE SECTION
3. MAJOR UNIT SECTION
4. MINOR UNIT SECTION
5. CALIBRATION SECTION
2.1)REPAIR
MAINTAINCE
&
CHASSIS SECTION
R&M CHASSIS SECTION
It is one of biggest department in Dadar workshop. In R&M Chassis section all defective buses itself are brought for overhauling. There are total 8 working pits each bus has different defect.The worker work out Problem. If it get solved then bus is sent to transportation. If it is not get solved then all the units like engine, gearbox , clutch plate assembly etc. are dismantled from the chassis and sent to respective section for overhauling. There are about 35 to 40 workers who work on defects. The whole R&M chassis section is inspected &controlled by four supervisors. The work time depend upon the number of defective buses coming in a day.
2.1.1)MAIN ACTIVITIES OF R&M CHASSIS SECTION:
Fig.1. workers working under pit.
1) To register new buses.
2) Scrapping of old buses.
3) Rear axle overhauling and replacement.
4) Front axle overhauling and replacement
5) Engine replacement of CNG, AC,MUTP.etc.buses.
Following steps are used for overhauling of front axle and rear axle.
Following steps are used for overhauling of front axle and rear axle.
6) Modification of parts/units which is not available ,repeated failure, easy to maintenance and to increase life of parts.
7) Chassis frame related defects like chassis long member, cross member, outrigger or expansion ,sole bar, filch plate problems.
8) Repeated depot defects like steering hard, fuel trouble, starting trouble, NCM clutch hard, running cross, engine related defects.
9) Other defect which cannot be attended at depot as per depot letter.
10) Fork lift maintenance and servicing.
11) Inspection or physical fitment of new or modified material.
2.1.2WORKING OF UNIT/COMPONENT OVERHAULED IN SECTION:
In R&M chassis section front axle and rear axle unit are overhauled.
Following steps are used for overhauling of front axle and rear axle.
Fig.2. Front axle
1) removed defective front axle taken on stand and file on.
2) separate both side brake assembly(Hub drum, inner-outer bearings, liners, S-camshaft assembly, Brake carrier plate, knuckled arms, brake chambers, Slack adjusters and sub-axle).
3) Removed parts and material cleaned.
4) checked axle beam –crack, bend, kingpin and feather hale w/o
5) checked all removed parts-crack, w/o and damaged.
6) Replaced if necessary.
7) Refitted all assembled parts with new hub seal and grease.
8) Both side hub bearing weighs 1 to 3.5 kg.
For front axle overhauled 29 man hours and for rear axle overhauled 40 man hours needed.
2.1.3)EQUIPMENTS&TOOLS USED IN SECTION:
Following equipments and tools used in R&M chassis section:
1)chassis stand
2)Decanting pump
3)Gauges-Ammeter& HRD, compressor pressure test
4)Machine-portable grinder, Electrical drill,Welding, Pedestal drilling.
5)Jacks –Hydraulic, pit, winches,crane, camel(hydraulic)
6)PA system
7)Pullers-front bearing,hub,stub.
8)Trolley-Battery box, winches jack, for different replacement.
9) wrenches-pipe 18”, torque
2.1.4)SAFETY PRECAUTIONS IN SECTION:
1) Before working make sure that workplace floor not greasy, wet, or dirty. 2)Do not seat on boxes or inverted scrap/garbage bins. Use seats or bentches as provided.
3)Keep your workplace free from dirt and congestion.
4Use dust bin for depositing used cotton waste instead of throwing them on floor.
5)Use grease guns, oil cans, to avoid oil spillage around the machine.
6)Do not take load in self body, use tools/equipment's for loading
7)Be sure that main switch of bus is off before start working on engine
8)Be sure that gar in neutral before start of bus, for checking
9) Keep gangways and passages clear to streamline material handling
10) While removing or assembling of rear axle be sure that jack will be rightly placed.
2.2)ENGINE
SECTION
ENGINE SECTION
Engine is heart of the vehicle.It is main and most important vast department of maintenance.Engine department is divided into 4 main parts i.e. assembling, dismantling, inspection, and testing. The entire defective engine is brought together. Only one or two engine is dismantle in a day with the help of three to four workers &two to three apprentices, and all the parts are sent to its respective department for overhauling like Water pump, compressor etc.
In assembling section only one to two engine are assembled in a day with the help of five to seven workers. All the parts required to assembling are brought together and then assembled. The whole engine section have three supervisor who finally inspect the assembled engine at the end of work.
2.2.1)ACTIVITIES OF THE SECTION:
Fig.1. apprentices dismantling engine
Engine section carries out overhauling and testing of engine removed by 25 zonal centers located at depots and docking section in R&M chassis for various defects. These engine are sent to Engine section through Material control section. Engine received are analyzed for the failure. Total life history of each engine is kept in engine section and it is used to analyze the defects and taking corrective action to reduce these defects.
The engine provides the motive power for all various functions which the vehicle or any part of it may require to perform. The engine for automotive use is of internal combustion type.
Engine overhauling done by following steps:
· Dismantling
· Degreasing
· Inspection
· Assembly
· Testing
After overhauling engines are sent to respective depots or R&M chassis,for fitting them on buses.
The various types of engine used in B.E.S.T:
1.CONVENTIONAL :370, 400, 401, 402, and 6.65
2. HINO : 6D, 6E, 4D, EURO-I, II, 6DTI PPPANTHER 6DTI.
3. AC : MATADOR, ISUZU, PEUGEST, PEUGEOT.
4. TATA : CUMMINS, STARCUS.
5. HINO CNG : EURO –II, EURO-III.
ENGINE PARTS:
The essential parts of the engine Are as follows:
I)Cylinder block II) Cylinder head,
III)Crankcase, IV) Piston,,
V)Piston rings, VI)Piston pin,
VII)Connecting rod , VIII)Crankshaft,
IX)flywheel, X)Valve and valve mechanism,
XI)Rocker arm, XII)Camshaft,
XIII)Accessories :Air- cleaner, oil filter, automatic choke, automatic heat
Control
XIV)Other parts : Spark plug, Ignition device, carburetor, Manifolds, Vibration damper.
2.2.2PROCEDURE OF ENGINE OVERHAULING:
DISMANTLING:
a) First engine putted on repair stand and be sure that engine is properly mounted on repair stand.
b) After that remove water pump and oil filter tube.
c) Remove exhaust manifold,water outlet fitting and thermostat.
d) Remove crankshaft pulley and oil pump, crankcase ventilation valve.
e) Remove rocker arm assembly, after remove feed pump and pipe and injectors.
f) Remove oil filter ,oil pan , cylinder head.
g) Remove timing gear cover, idle gear, camshaft and water pump.
h) Remove front end plate.
i) Remove flywheel housing and clutch and flywheel.
j) After remove crankshaft, oil gallery plugs and exhausts valve and springs.
DEGREASING AND INSPECTION:
Fig.2.Inspection
a) After dismantling, all parts of engine kept in tank which is filled with ‘Diva’.
b) After that all parts are inspected carefully.
c) Engine block is checked by puncture testing, if puncture test and sizes of engine found ok then it taken for assembly
d) Oil cooler assembly checked in special oil testing machine.
ASSEMBLY:
Engine assembly done in following stages:
a)1st stage :
In this stage following activities are done:
i)Fitment of crankshaft on engine block.
ii)Fitment of flywheel housing.
iii)Fitment of timing gears and its cover.
Fig.3. Assembly of engine
c) 2nd stage :
In this following activities are done
1. Fitment of cylinder liner and piston-connecting rod assembly.
2. Fitment of engine oil sump with strainer and oil pump.
3. Fitment of water pump, thermostat, air compressor, F.I pump oil cooler
assembly.
4. Fitment of cylinder head with proper torque, rocker arm assembly with proper torque.
5. Fitment of damper pulley, belt, viscous clutch.
6. Doing tappet setting and fit tappet cover
TESTING:
HINO ENGINE TESTING PROCEDURE:
a)Precaution:
v Engine should not be run on ‘no load’ for more than 5 minutes.
v The engine should not be shut sown abruptly. Allow the engine to idle for 5 minutes before shut off.
Testing procedure:
Fig.4. Engine on test bed
Preliminary test:
a) Run the engine as cycle given below.
b) Crank the engine with fuel pump stop lever pulled back.
c) Check oil circulation to rocker lever.
d) Start engine after oil appears in the rocker arm assembly.
2.2.3SPECIAL TOOLS AND MACHINARY USED IN ENGINE SECTION:
1. Hydraulic press5. cylinder liner puller 9. battery brush
2.hand grinder 6. Steam seal press10.Torque wrench
3.Oil cooling system tester 7. Idler gear shaft puller
4.Cylinder liner guide 8. Electrical crane
2.3) MAJOR
UNIT SECTION
2.3.1)What is major unit?
Lets go into brief description of about major unit. As name is suggesting it consist of overhauling of major/big parts of buses. It deal with gearboxes, differentials, tie rods and power steering system.
It consists of 6 section:
1. Gearbox overhauling.
a. Constant mesh gear box
b. Synchromesh gearbox
2. Differentials
3. Fork and bearing overhauling
4. Gear shifter overhauling
5. Tie rod and draglink.
6. Steering pump and vane pump.
2.3.2)Working of major unit :-
In the major unit ,the parts of bus with various major defectives which cannot be repaired at depot level are dismantled and are sent to major unit.
2.3.3)Distribution of work:-
The distribution of work depend on defective parts entering per day. Each table is provided with different defective unit .One skilled worker who has very thorough knowledge about unit is sent to respective work table. One unskilled worker is sent with skilled worker for helping in dismantling procedure. One common cleaner is provide to two to three work table.
2.3.4)Main activities of major unit:
a) Overhauling of gearboxes
b) Overhauling of steering box.
c) Overhauling of steering pump.
d) Overhauling of differential.
e) Overhauling of draglink.
f) Overhauling of the tie rod.
g) Overhauling of gear selector, exchanger.etc.
2.3.5)PROCEDURE OF OVERHAULNG OF VARIOUS UNIT IN MAJOR UNIT :
1)ZF GEARBOX OVERHAUING:
Fig.1(a). synchromesh gearbox Fig.1.(b).assembly of gearbox
Dismantling:
a) Mount gear box on work table.
b) Remove the selector linkage, selector assembly, speedo assembly, External plug for selector guide rod, reverse idle cover and lock reverse spindle.
c) Remove flange nut using puller companion flange.
d) Remove connection plate and preserve shims for input shaft bearing and counter shaft bearing.
e) Remove connection housing, retainer on input shaft and fever out spilt locks, spigot bearing.
Inspection:
Clean all parts and inspect them replace if necessary.
Assembly:
Assemble the transmission in the reverse order dismantling,noting the following points:
a) Assemble the synchronizing unit.
b) When installing main shaft see that needle bearing rollers in the main shaft drive are correctly positioned .etc
2)ZF VANE PUMP OVERHAULING :
After removing the power steering pump from engine follow the steps mentioned below for dismantling , inspection and assembling.
Dismantling:
a) Clean the rear cover properly.
b) Remove the hook spring ring.
c) Mount steering pump in the fixture the lightly press the rear cover by hydraulic press by spring tension the break over will come out automatically.
d) Remove rotor set and pressure plate.
e) Remove oil seal from the frank end.
f) Remove the snap ring and then remove shaft with bearing.
g) Remove the flow control valve unit.
Fig.2. ZF steering box
Inspection:
a) Check the pressure plate, front plate and rotor sets for any damage, scores and pits. It found defective replace the same.
b) Check the ratter and needle bearing for any damage and if found defective.
c) Clean and check the shaft for any scores, pits and damage, replace if found defective.
d) Check the flow control valve for proper functioning and replace piston, springs if found defective.
Assembly:
a) Hold the pump housing in the fixture.
b) Insert the shaft with bearing then fix retaining ring.
c) Move the front oil seal.
d) Fix the body inside O ring and support ring.
e) Fix the dowel pin inside body.
f) Fix the rear plate properly on dowel pin.
g) Fix the rotor set and pressure plate.
h) Place the spring, sealing ring and then fix the cover.
i) Finally press the rear cover and press hook spring properly.
j) After assembling of pump, mount it on test bench and check it for proper functioning and performance.
3)DIFFENTIAL OVERHAULING:
Dismantling:
Fig.3.Differential on stand
a) Mount the carrier on stand.
b) The same gear set is to reused. Record the black lash before dismantle.
c) Remove the thrust screw and jam nut.
d) Make match mark on one carrier leg and bearing cap.
e) Remove cotter pins using small drift and hammer, cap screw and washer of bearing cap, bearing adjusting ring.
f) Lift the differential case ring gear assembly.
g) Mae match marks on the differential case halves.
h) Remove the lock wires and differential case bolts and separated case halves
i) Remove spider, pinions, side gears and thrust washer, gear mounting bolts and lock plates, ring gear from differential case using press.
j) Remove the bearing from differential case using bearing putter or press.
k) Fasten a flange bar to companion flange, pinion nut and washer.
l) Remove the companion flange, pinion nut and washer bearing cage and shims
Fig.4. Sun gears and star gears
m) Remove driver pin from baring cage using press.
n) Remove the oil seal, take cutter bearing cone, bearing cap from the cage .
o) Remove the inner bearing cane using the split puller/press.
p) Remove the snap ring, spigot bearing.
Inspection:
a) Using kerosene or diesel clean the all parts of differential and dry the part immediately after cleaning.
b) Apply axle lubricant/rest privative over the reusable parts.
c) Inspect the all parts replace if necessary.
Assembly:
a) Mount the differential case on repairing stand.
b) Assembled the ring gear assembly.
c) And put on differential case using puller as per marking.
d) Assembled the spider, pinion, side gear and thrust washer.
e) Assembled all parts one by one.
f) After assembly apply marking compound to six teeth of ring gear. Rotate the ring gear, forward and backward. So that this teeth go pass pinion to obtain clear pattern.
4)DRAG LINK OVERHAULING:
Fig.5.Drag-link
Dismantling:
a) Fix the drag link in bench vise.
b) Dismantle the drag link sockets RH&LH from drag link.
c) Remove the nut MIU for socket, shim, spring, outer diameter, ball pin, inner diameter, grease nipple, spilt pin for socket cup.
Inspection:
a) Clean all parts in kerosene or diesel.
b) Check drag link bent or not.
c) Check all socket assembly of RH&LH sides, changed if necessary.
Assembly:
a) Fix the drag link on bench vise.
b) Screw the drag link cup sockets on drag link respective sides.
c) One by one assemble all socket assembly.
d) Last checked the load on ball pin, it kept between 10 to12 kg and locked nut, by using split pin..
SPECIAL MACHINARY/TOOLS &EQUIPMENT'S USED IN SECTION:
1) Power steering tester
2) Lifting devise
3) Oven
4) Double cylinder hydraulic press
5) Puller companion flange
6) Range steering tester
7) High pressure Hoses
SAFETY PRECAUTIONS:
1) Before working make sure that workplace is not greasy, wet & dirty.
2) Use grease guns, oil cans to avoid oil spillage around machine.
3) Do not take load on body, use crane or equipment given for loading.
4) While any assembly mount on stand, be surely that it is properly mounted.
5) Do not handle any machine without knowledge.
6) After assembling be sure that all parts are well assembled.
2.4)MINOR
UNIT
2.4.1) What is minor unit?
As a name indicates it deals with overhauling of some minor parts or unit. Itconsists of 6 sections. In minor unit overhauling of different small units such as pressure plate, propeller shaft, air dryer, and all air brake system parts .etc. are done.
2.4.2) Distribution of work:-
In pressure plate section about 6 workers are utilized .In that 3 areskilled and other 3 are helper. In overhauling of air brake system units, 2 skilled worker are put together with helpers. About 6 to 7 air dryers are brought to Dadar workshop from different depots every day for repairing purpose. The Whole minor section has two supervisors who look into the work & manage workers.
Propeller shaft:-
In propeller shaft section about 2 workers are send for assembling of each shaft, In that one is skilled other is cleaner or helper. About 4to5 shafts are assembled per day.
Clutch plate:-
Fig.1.clutch plate
It is smallest of all sections in minor unit. There are 2 types of clutch plates organic and ceramic each clutch plate has only one worktable .The assembling of ceramic clutch plate is very easy and it very less time.
But assembling of organic clutch is slightly difficult. Hydraulic pressing machine is required for its assembling process.
Brake shoe overhauling:-
In shoe overhauling section all the defective brake shoe are brought in workshop for repairing. The work of brake shoe section is to dismantle the brake shoe &assemble it again using the new components. The Brake shoe areriveted on brake drum. Every day target is given to different sections & that target is inspected by the supervisor
2.4.3) ACTIVITIES OF MINOR MAIN UNIT:
1) Pressure plate overhauling
2) Propeller shaft overhauling
3) Air Dryer with tire inflate overhauling
4) Dual Brake valve overhauling
5) Clutch plate overhauling
6) Brake shoe over overhauling
2.4.4) PROCEDURE OF VRIOUS PARTS OVERHAULIED IN UNIT
1) PRESSURE PLATE:
| Fig 2.assembly of pressure plate Fig.2.Assembly of pressure plate Dismantling: |
a) Place cover assembly and clutch discs into the above and clamp cove to arbor press. Remove the three hold down bolt and locknuts from the cover assembly. Now slowly release the press.
b) Remove Cast iron cover and nine pressure spring. Remove circle and washers from the pressure plate pins. Remove the release levers; dismantle the eye bolt pins from the eyebolts. Now press needle bearing in the eyebolts and pressure plate
Inspection:
1. After the cover assembly has been stripped, clean all parts thoroughly.
2. Inspect the all parts. Discards components with visual defects. i.e. worn or damaged.
3. The pressure plate must be replace if friction face is severely heat cracked or it is warped in excess of 0.8 mm or if there is excessive wear in the drive slots
4. Cast iron cover must be replacing if any cracks are present or drive blocks are worn or cover is distorted or damaged
5. All pressure springs to be checked for load at working height and for free length. Springs should be discarded if distorted or heat affected.
6. In flywheel, check for cracks, unevenness, overheating, and scoring marks.
7. The flywheel must be replaced if friction face is severely cracked or it is warped in excess of 1 mm.
Assembly:
a) Place new clutch disc assembly on special fixture or flywheel. This will act as gauge plate for setting the release levers.
b) Place the pressure plate on top of the driven disc.
c) Assemble the eye bolt, adjusting nut, release levers, retractor springs, retaining springs, retaining clips, and eye bolt pins.
d) Place the pressure springs and Ground steel washer of correct quantity over the springspring bossed on the pressure plate. Always replace pressure springs as a set.
e) The cover can now be pressed into position, taking care to engage the driving blocks into the mating slots of pressure plate and the adjusting nuts/eyebolts in holes on the ring cover as the springs are compressed. Ensure that the springs are seated correctly.
f) When the pressure plate cover has been put into position, the locknuts can be fitted. Now the assembly is ready for setting lever height.
g) The lever heights are set by tuning the adjusting nits while at the sometime holding the locknuts with a spanner. The position of the 3 levers in the case of 330 mm diameter clutch with a Cast Iron cover is checked from the flat surface of flywheel or arbor press to top of the collector ring at minimum 3 points.
h) Having adjusted the collector ring to the specified height, hold the adjusting nuts in position using 2 slots and tighten up the locknuts to the required 12 Kim torque. Recheck the collector ring heights to ensure they have not moved.
2) PROPELLER SHAFT:
Dismantling:
1) Remove the circles and holds the stub ball yoke in bench vice.
2) With a sort nosed drift drive out the bottom bearing cup. 3)Invert the propeller shaft and drive out the opposite bearing cup.
4) Repeat the procedure to remove bearing cups from link flange yoke. Fig.3. Propeller Shaft
5)For dismantle slip joint end, check the arrow marks and pull out the sleeve yoke from the splinted shaft after the dust cap.
6)To dismantle centre joint bearing, hold the propeller shaft on a fixture. Remove the split pin and the nut retaining the flange using extractor companion flange.
7)Press out the bearing from center bearing housing and remove oil seals.
Inspection:
1. Clean all the components thoroughly.
2. Visually inspect the components for wear or damage.
3. A total of 0.010” circumferential movement measured on the outside diameter of the splinted should not be exceeded.
4. Check for max run out of 0.020” at centre of tube and 2” from the weld.
Assembly:
1. the Centre bearing.
2. Press the oil seals in the bearing housing and end cover.
3. Press the bearing in the bearing housing and packed with grease.
4. Insert the spacer and press up against the abutment shoulder.
5. Replace the spacer and end cover with oil seal.
6. Replace the Companion flange making certain i.e. good fit hard up, the taper. Replace and tighten the nut to 55 Kim, and secure with the split pin.
7. Fill the assembly with grease through the lubricator provided.
8. Replace worn out parts.
9. Assemble the needle rollers in the bearing cups. Smear the walls of the cups with grease to retain the needle rollers in place.
10. Renew the cork journal shoulder should be applied with shellac prior to fitting the retainers to get a good oil seal. Use tubular drift to ensure that the gaskets and retainers fit down on the grunion shoulders.
11. Insert the journal grunions in the yokes. Tap or press the bearings into position at opposite ends of the journals grunion in turn with a soft drift.
12. Refit the circles.
13. If the joint appears to bind top the lugs lightly with a mallet which will relieve any pressure of the bearing cup on the end of journal grunion arm.
14. When replacing a sliding joint on a shaft be sure that marks on the flange and sleeve or stub ball yokes are in line this can be checked by observing whether the arrows stamped on the sleeve yoke and stub shaft are in line. Screws up the dust cap cover the cork and steel washers by hand.
15.Lubricate the joints and sleeve yoke through the grease nipples provided.
3) DUAL BRAKE VALVE:
| Fig 4.Dual brake valve |
1. Clean the exterior of the unit.
2. Loosen and remove the stop light switches and low pressure indicator switches, if provide.
3. Remove one of the split pins of the fulcrum pin which secure the pedal on the mounting plate.
4. Push out the fulcrum pin and remove the pedal assembly.
5. Remove one of the split pin tram the plunger pin and remove the pin and plunger from the pedal.
6. Remove the boot from plunger.
7. Loosen and remove mounting plate.
8. Mark the position of upper and lower bodies to avoid wrong position of ports during re-assembly.
9. Dismantle lower and upper body
Cleaning and Inspection:
1) Clean the metallic part in cleaning solvent and blow dry with compressed air.
2) Ensure that the metering holes and free from \ blockage in the upper and lower bodies.
3) Check the upper and lower bodies for thread/part face damage.
4) Inspect the mounting plate, piston, plunger and venting guide for damage of wear and check the spring.
Assembly:
1) Replace the old part scrapped during dismantling and also replace the parts found to be unserviceable during inspection.
2) Lubricate the piston bores of upper and lower bodies and sealing ring spacers with multipurpose grease.
3) Install the new ‘O’ rings on the piston. Install the guide rings on the primary piston and smear with grease.
4) Assemble the lower body.
5) Assemble the upper body.
6) Assemble in the plunger groove assemble to the brake pedal by aligning the pedal holes with plunger holes in line and insert the plunger pin.
7) Secure the fulcrum pin by split pins at the ends and fold its ends.
8) Assemble the stoplight switches in the auxiliary part of the deliveries and the low pressure indicator switches in the auxiliary parts of the inlets, along with aluminum washers if provided.
4) CLUCH PLATE:
Dismantling:
I. First the clutch plate holds in vice, and then with help of punch and hammer remove all the rivets which joint face plate and trump
II. After dismantle all the parts inspect the parts and clean in diesel
Fig.5(a). Ceramic clutch plate Fig.5(b) Organic clutch plate
Assembly:
1) First hold the trump on vice and put the face plate on it that way they look like sandwich means trump puts between two face plates.
2) After one by one all 38 riveters are punch on the plate, that way the trump and face plate are fitted tightly.
2.5)CALIBRATION
SECTION
2.5.1) CALIBRATION SECTION:-
It is one of the smallest department in Dadar workshop. It only deals with overhauling of Fuel Injection pump, feed pump, and Injectors. Etc. And calibration of them. Overhauling of FI pump and calibration of them is main part of this section. Everyday about 2to 3 FI pump are overhauled and calibrated. And 35 to 45 injectors are made. And Feed pump as per requirement.
2.5.2) Distribution of work:-
In the calibration section, There are about 12 to 15 workers in this section, In this 4 to 5 skilled are send for calibration of FI pump, about 6 worker are used for dismantling of FI pump, and remain are for Injectors and feed pump. There is only one supervisor in this section.
2.5.3) MAIN ACTIVITIES IN THE SECTION:-
Fig.1. Calibration of FI pump
1. To calibrate FI pump
2. To overhaul fuel injectors
3. To overhaul feed pump
4. To test the fuel injectors and feed pump
2.5.4) WORKING OF UNITS/COMPONENTS OVERHAULED IN SECTION:-
In the calibration section FUEL INJECTION PUMP is important unit.
OVERHAULING OF FUEL INJECTION PUMP:-
Dismantling:
1.
| Fig.2.Dissmantled Euro-II Fi pump |
2. Remove upper cover and EDC(if available) unit.
3. Remove plunger assembly and bolt on it.
4. Remove bearing under it.
5. Remove cam plate.
6. Remove gearing assembly.
7. Remove all washers and springs and dismantle pump body
Assembling:
1) First all dismantled parts are washed and clean with compressed air
2) Assemble the all cam plate assembly on body of pump
3) Fit the bearing and gearing assembly on it
4) Fit the plunger and small plate on side to it
5) Assemble vane pump on upper side
6) Fit the upper cover or EDC unit on it
While fitting this observe timer travel moment and adjust it as per timing
Fig.3.worker assembling FI pump
TESTING AND CALIBRATION OF FI PUMP:-
In this testing, pump is mounted on test bench, and testing is done as per following specifications
| SETTING:- | |
| Speed(rpm) | 1000 |
| Boost pressure in bar | 1.0 |
| Time travel in mm | 1.7+0.2 |
| Vane Pressure in bar | 7.5+0.3 |
| FULL LOAD DELIVARY:- | |
| Speed(rpm) | 1200 |
| Boost pressure in bar | 1.0 |
| Delivery quantity in cm3/500strokes | 66.5+0.25 |
| Max. spread in cm3 | 3.0 |
| Speed(rpm) | 540 |
| Boost pressure | 0.125 |
| Delivery quantity | 50+0.25 |
| Speed(rpm) | 540 |
| Boost pressure | 0 |
| Delivery quantity | 45+0.25 |
| IDLINGG DELIVERY:- | |
| Speed(rpm) | 245 |
| Boost pressure | 0 |
| Delivery quantity | 16+0.5 |
| Max. spread in cm3 | 4.0 |
| MAXIXMUM SPEED REGULATION:- | |
| speed | 100 |
| Boost pressure | 1.0 |
| Delivery quantity | 21.5+1.0 |
| STARTING FUEL DELIVERY:- | |
| Speed(rpm) | 100 |
| Boost pressure | 0 |
| Delivery quantity | 62.5+12.5 |
| TESTING:- | |
| Speed(rpm) | 1000 |
| Boost pressure | 1.0 |
| Timer travel | 1.2-2.2mm |
| Speed(rpm) | 950 |
| Boost pressure in bar | 1.0 |
| Timer travel | 0.3+00.7 |
| VANE PUMP PRESSURE:- | |
| Speed | 1000 |
| Boost pressure | 1.0 |
| Vane pump pressure | 6.7to8.3 |
| Speed | 500 |
| Boost pressure | 1.0 |
| Vane pump pressure | 5.0 |
| OVERFLOW QUANTITY:- | |
| Speed | 500 |
| Boost pressure | 0 |
| Overflow quantity | 111-167 |
| Speed | 1200 |
| Boost pressure | 1.0 |
| Overflow in cm3/10 strokes | 125-209 |
| FUEL DELIVERIES:- | |
| 1. END STOP:- | |
| Control lever position | max |
| Speed | 1200 |
| Boost pressure | 1.0 |
| Delivery quantity | 64.5-68.5 |
| speed | 540 |
| Boost pressure | 0.125 |
| Delivery quantity | 47.5-52.5 |
| speed | 540 |
| Boost pressure | 0 |
| Delivery quantity | 43-47 |
| Speed | 1325 |
| Boost pressure | 1.0 |
| Delivery quantity | 16.5-26.5 |
| Speed | 1360 |
| Boost pressure | 1 |
| Delivery quantity | Max 1.5 |
| 2. IDLE STOP | |
| Control lever position | Idling |
| Speed | 245 |
| Boost pressure | 0 |
| Delivery quantity | 13-19 |
| Speed | 350 |
| Boost pressure | 0 |
| Delivery quantity | Max 1.5 |
INJECTORS OVERHAULING:-
| Fig.4.worker checking injector nozzle |
1. while dismantling or assembling of injectors care should be taken that its nozzle’s needle should not get damaged
2. First remove the nozzle cover on injector by placing it on bench vise
3. Remove nozzle needle, nozzle, washer, spring, injector adaptor.etc.
4. Assemble the injector in the reverse order of dismantling,noting following points
5. Needle and all parts should be well cleaned
6. The spray should come out from all holes of nozzle
| Fig.5.Injector testing machine |
1) Chattering test:
a) Operate the lever for 1to 5 strokes/sec
b) The spray should be come out through all holes in atomized form.
c) In slow lever operation.i.e.1to2 strokes/sec nozzle should chatter with whistling noise pressure gauge should be by pass
2) Opening pressure test:
I. Operate the tester handle to 2to3 strokes/sec with pressure gauge connection on position. Note the pressure at which spray brakes.
II. The recommended opening pressure is different for various types
3) Seat tightening test:
I. Operate the hand lever until the pressure gauge indicate 20 bar less than the recommended opening pressure
II. The nozzle is considered as satisfactory if no drop of oil falls from the nozzle within sec.
4) Back leak test:
I. Operate the hand lever up to Injector opening pressure& leave the hand lever
II. The pointer should not fall down within 5 sec
III. At pressure 90 to40 bar if pointer fall down faster it is suppose that injector is back leak.
Opening pressure for various injectors:
| Type of bus | Type of injector | Opening pressure |
| BH-0 | Multi hole(5) | 220-230 |
| BH-I | Multihole(6) | 230-240 |
| BH-II | Multi hole(5) | 246-260 |
| BH-III | Multihole(6) | 246-260 |
| NESTIBUHE | Multihole(5) | 230-240 |
| PEGEOT | Single hole | 125-135 |
CHAPTER-3
PROJECT NO 1:-
OVERHAULING OF POWER STEERING SYSTEM
3.1) AIM:- To overhaul the power steering gear and steering pump
About the power steering :-
The integral power steering gear is precision assembly. Power Steering system is system which help driver to rotate steering at less power .It use power of oil which is specially made for it.
3.2) Purpose:-
To turn front axle of vehicle using less power or very easily.
Sample:- ASHOK Leyland- ZF POWER STEERING GEAR
3.3) Removable causes:-
For overhauling purpose
For oil changing purpose
Overhauling of steering pump-Noisy, oil dirty, oil bearing damage, pressure not reaching.etc.
3.4) Procedural sequence:-
v Dissmantling of steering gear,pump
v Overhauling of steering gear,pump
v Reassembling of steering gear, pump
v Trouble shooting of ZF steering gear, pump
v Maintenance and precautions
3.4.1) Dissmantling of steering gear:-
1. First clamp the steering gear properly on bench.
2. Remove upper bolts on the piston assembly.
3. Remove screw on gear sector shaft .
4. Remove piston assembly and sector shaft.
5. Send all parts dismantled for cleaning and washing.
3.4.2) Dismantling of steering pump:-
1. Clean the rear cover properly.
2. Remove the hook spring ring.
3. Mount steering pump in the fixture the lightly press the rear cover by hydraulic press by spring tension the break over will come out automatically.
4. Remove rotor set and pressure plate.
5. Remove the oil seal from the frank end.
6. Remove the snap ring and then remove shaft with bearing.
7. Remove the flow control valve unit.
3.4.3) Overhauling of steering gear,pump:-
1. Check the pressure plate, front plate and rotor sets for any damage, scores and pits. If found defective replacethe same.
2. Check the ratter and needle bearing for any damage and if found defective.
3. Clean and check the shaft for any scores, pits and damage, replace if found defective.
4. Check the flow control valve for proper functioning and replace piston, springs if found defective.
3.4.4) Reassembly of steering pump:-
a) Hold the pump housing in the fixture.
b) Insert the shaft with bearing then fix the retaining ring.
c) Move the front oil seal.
d) Fix the body inside ‘O’ ring and support ring.
e) Fix the dowel pin inside the body.
f) Fix the rear plate properly on dowel pin.
g) Fix the rotor set and pressure plate.
h) Place the spring, sealing ring and then fix the cover.
i) Finally press the rear cover and fix hook spring properly
j) After assembly of the pump mount in a test beach and check it for proper functioning and performance
Fig.1.ZF steering pump
.
k) .
3.4.5) Reassembly of steering gear:-
1. Mount cleaned and washed body of gear on clamping bench
2. Assemble the sector shaft assembly and piston assembly with proper alignment
3. Fit screw on sector shaft assembly and bolts on piston assembly with torque
4. Send steering gear on test bed for testing
Fig.2.RANE STEERING TEST BED
3.5) Trouble shooting of ZF steering pump:-
1.Loss of oil:-
REMADIES: With engine running, check oil level.Repair all external leaks.
Note: While tighten hose pipes and connectors make use of two sppaners, one to hold and one to tighten, to prevent slippage and rotation of adaptors, on the oil reservoir,pump and steering gear.
2.Wrong grade oil:-
REMADIES: Use Automatic Transmission or on Fluid(ATF) only, to specification Dexron IID/IIE/III or Mercon-M.
1) Indian oil corporation LTD. Servo Transdex-II
2) Castrol India LTD.CASTROL TQD.
3.Air in oil:-
REMADIES: Oil is foaming. Pump is sucking in air the shaft seal of the pump or at the suction line.
Tighten all connectors & Pipes from oil tank to pump.
4.Oil Dirty;-
REMADIES: Change oil and filter. Dirt particle may cause pump to fail and Oil change recommended between 50000 km to 80000 km.
5.Hydrulic steering Limiter Does not Cut off:-
REMADIES: Check if limiters are disturbed
Note. Limiters are set while Commissioning of the vehicle, Correct the setting as per service manual.
6.Permanent max. pressure Reached while steering;-
REMADIES: Axle not smooth, overloading of steering axle, Tyres worn out Tyre inflation too low, Steering geometry disturbed can cause the problem. Correct the setting as per manual.
7.while driving under extreme conditions,Driver holding steering wheel turned:-
REMADIES: Pump is working for longtime under max.pressure conditions.Development of heat and failure of pump
3.6) MAINTENANCE AND PRECAUTIONS:-
3.6.1) MAINTENANCE:-
1. REVOMMENDED OILS.
The system requires a special oil ”AUTOMATIC TRANSMMISSION FLUID”(ATF) having following specifications, Dexron IID/IIE/III
For example: The oil recommended by a oil company will be as follows:
1) Indian oil corporation. Ltd. Servo Transdex-II
2) Castrol India .ltd. CASTROL TQD .etc.
2. OIL FILLING.
Remove cover of oil tank and pour clean, dust free oil into tank to three fourth of its capacity. Jack up the axle, crank the engine, as the oil level goes down keep topping up until no more oil level drop is observed. Now start the engine, to get oil level up to maximum mark of dipstick, top up if required
3. BLEEDING.
Jack up vehicle and with the engine running turn the steering wheel to both lock position several times and slightly(for max 5 sec) over ride the axle stops. This will enable to vent air from the system. Now stop the engine and check oil level. The oil level should not increased more than 10mm to 12mm. More increase will indicate improper bleeding of air. Repeat process.
4. CHECKING OF OIL LEVEL.
Check oil level at interval of 5000-6000 km or after 100-120 hours of operation
5. CHANGE OF OIL AND FILTER IS RECOMMENDED TO BE CARRIED OUT AT EVERY FOLLOWING MILEAGE.
| For vehicles running mixed And short distance | On construction sites and off the road |
| 80,000 km 50,000km | 50,000 km 30,000miles 1250 op.hours |
3.6.2) PRECAUTIONS:-
1. Do not use contaminated oil.Oil mixed with water, any other oil, diesel, kerosene, and dirt should not be used at any cost.This may cause pump failure and gear failure.
2. Do not mix different brands of oil.
3. Do not allow oil level in the oil tank yogo to below minimum mark while the engine is running
4. Do not use reconditioned oil.
5. Ensure that no oil leaks through any of hose-pipes, adaptors, steering gear, pump and oil tank
6. Check the oil level in the tank at intervals of 5000-6000 km.
7. Ensure proper belt tension on steering pump and replace belt as per recommendation
CHAPTER-4
ASSIGNMENT NO-1
ELECTRONICALLY CONTROLEDAIR SUSPENSION SYSTEM(ECAS)
4.1) ELECTRONICALLY CONTROLED AIR SUSPENSION SYSTEM(ECAS):-
1) Air suspension-Conventional
2) Electronic Controlled Air Suspension
3) Functions
4) Components Description
4.1.1) AIR SUSPENSION-CONVENTIONAL:-
1. The mass of the vehicle body rests on the air bellow which is mounted on the top of the vehicle axle.
2. The compressed air from the reservoir is fed into the Air bellow through leveling valve.
3. The leveling valve is fitted on the chassis.
4. The leveling valve is operated by a lever whose one end is attached to a link and the other end to the axle as shown.
5. The inlet port of the valve is connected to the reservoir and the outlet port is connected to the air bellows.
6. The vertical movement between the vehicle axle and the chassis is detected by the lever which adjusts the leveling valve air pressure accordingly andmaintains constant ride height
| Fig.1.conventional air suspension |
7. Based on the load of the vehicle, the air pressure in the bellows are controlled by the leveling valve there by maintaining the ride height
Why ECAS Used?
Constant vehicle height irrespective of the load:
i. The vehicle ride height can be maintained constantly irrespective of the load by appropriate parameter setting.
ii. It is realized by using height sensors, which transmits the height level of the vehicle periodically to the ECU.
iii. ECU will compare these current values with the preset values for the vehicle height been stored in the ECU during parameter setting.
iv. Any deviation in the vehicle height will be adjusted by actuating the solenoid valves which in turn charges or discharge the bellows to maintain the constant ride height of the vehicle.
Lowering and Raising the height of the vehicle
1. Depending upon the road condition the vehicle ride height can be changed.
2. On bumpy road the bus ride height can be raised to avoid damage to the vehicle.
Reduction of air consumption:
1. When the vehicle is in motion minor changes in vehicle ride height will not cause
2. further build up of air pressure in bellows.
3. This is being facilitated in ECAS by maintaining the tolerance of 8 mm and that can be done by parameter set in the ECU.
4. Thereby reducing the compressor duty cycle and a saving of 25% in the air consumption is achieved.
Kneeling function:
1. Kneeling is lowering of the bus to make easy boarding and alighting of the
2. passengers (especially for disabled people) into the bus.
3. Based on the parameters set, kneeling can be achieved on the whole of one side, or on the axle (usually the front axle).
4.1.2) ELECTRONICALLY CONTROLLED AIR SUSPENSION SYSTEM:-
I. ECAS is an electronically controlled air suspension system, it increases operating comfort and makes raising /lowering process easier.
II. In an ECAS system bellows pressure is controlled by an ECU, which continuously monitors the electrical signals transmitted by the height sensors and there by actuates the solenoid valve.
III. Depending on the signal received from the ECU the solenoid either inflates or exhausts the respective air bellows.
IV. ECAS is a highly flexible system, different types of kneeling can be performed.
V. ECAS incorporates comprehensive safety concept, error memory and diagnostics.
VI. High speeds of all control process achieved by large valve cross sections.
| 1. ELECTRONIC CONTROL UNIT 3. HEIGHT SENSOR 2. SOLENOID VAVLE . 4. AIR BELLOWS 5. REMOTE CONTROL UNIT 5 1. SOLENOID VALVE |
Fig.2.ECAS
4.1.3) FUCTIONS:-
ELECTRONIC HEIGHT CONTROL AND LEVELING:-
1. The height sensors constantly measure the distance between the axles and the vehicle body and sending the data to the Electronic Control Unit.
2. The data will be changed whenever the vehicle is loaded or unloaded .
3. The changes are registered by the ECU which through the use of solenoid valve will automatically adjust the suspension bellows to ensure the proper ride height level.
KNEELING FUCTION :-
When stationary the vehicle can be raised and lowered to facilitate the passengers at the press of the kneeling button.
HIGH RIDE FUCTION:-
1. Allows the driver to raise the vehicle in driving conditions where sharp
break over (e.g. at railway tracks) or steep road angles (e.g drive ways
,entrance ramps) occur.
2. This will prevent the vehicle from bottoming out.
LOW RIDE FUCTION:-
1. Allows the driver to lower the vehicle for access to areas where low overhangs and canopies exist.
4.1.4) COMPONENT DESCRIPTION:-
1. ELECTRONIC CONTROLED UNIT:-
| Fig 3. ECU |
The ECU compares the readings given by the height sensors periodically with the preset levels stored in the ECU.
If there is any deviation exceeding beyond the tolerance band, solenoid valves are activated by ECU.
Solenoid valve will increase or decrease the pressure in the air bellows and the actual level is adjusted to the preset level.
By receiving the driver input from dashboard, ECU facilitates the following functions,
o Raising & Lowering of the vehicle
o Kneeling function
o Normal level
o Blink code diagnostics
OTHER FUCTIONS:-
a. Storing various height level values
b. Data exchange between Remote Control Unit (RCU) and Diagnostic controller
c. Regularly monitoring function of all system components.
d. Plausibility testing of the incoming signals received (for error detection)
2. LEVELING VALVE:-
1. The vehicle body with its leveling valve will move down as the load on the body is increased.
2. The linkage between the vehicle axle and the leveling valve raises both lever (f) and guide(d) via the eccentric cam (e).
3. As the guide (d) moves up, it also lifts the pin, thus opening the inlet valve (b), allowing air from reservoir to flow through via port 1 and check valve (a) into the air bellows which are connected to ports 21 and 22.
4. As the pressure in the air bellows increases, the chassis height is adjusted and lever (f) causes inlet valve (b) to close .
5.
| Fig.4.Leveling valve |
6. Now lever (f) with eccentric cam (e) and guide (d) are pulled down. This causes the pin to be move downward from its seat on inlet valve (b) and permitting excess pressure from the bellows to atmosphere via drilling (c) and Exhaust port 3.
7. This will cause the chassis height to be lowered and lever (f) will be returned to its horizontal position there by gaining a balanced position.
HEIGHT SENSOR:-
I. Height sensor contains a coil in which an armature moves up and down via connecting rod.
II. Connecting rod with lever is fitted to the vehicle axle.
III. As the distance between chassis and axle changes, the lever is moved accordingly.
IV. This causes the armature to move in or out of the coil which changes the coil inductance.
V. The coil inductance is being measured by ECU.
VI. ECU will compare these values with the preset values stored in it and activates the solenoid valves to charge and discharge the bellows accordingly to maintain the ride height constantly
Fig.5.Height sensor
VII. Fitted in the vehicle chassis with its lever fitted with vehicle axle via connecting rod as shown .
VIII. The height sensor’s measuring range is between +43° and -40°.
IX. The maximum turning range of the lever (± 50°) must not be exceeded.
X. The inductance is evaluated in excess of 50 times a second by the ECU
CHAPTER-5
ASSIGNMENT NO 2
STUDY OF
AC SYSTEM
ON
KINGLONG BUSES
5.1)WHAT IS REFRIGERATION & AIR CONDITIONING?
• To keep temperature of particular chamber always bellow atmospheric temperature that process is known as refrigeration.Air conditioning means removal of heat.
Different cycles used for the refrigeration are:
(1) Reversible Carnot cycle.
(2) Bell-Coleman cycle.
(3) Vapour compression cycle.
(4) Vapour absorption cycle.
Three types of air conditioning systems present in BEST undertaking on king long buses as follows
| SR NO. | TYPE | COMPRESSOR |
| 1 | SPHEROS (AMERICAN) | BITZER (650 CC) |
| 2 | CARRIER (AMERICAN) | BITZER (650CC & 550 CC) |
| 3 | HAIGER (GERMAN) | BOCK (FK 40 & 650 CC) |
5.2) AIRCONDITIONING COMPONENTS
• COMPRESSOR
• DISCHARGE SERVICE VALVE
• CONDENSER
• LIQUID RECIEVER TANK
• KING VALVE
• FILTER DRIER
• SIGHT GLASS
• THERMOSTATIC EXPANSION VALVE
• EVAPORATOR
• SUCTION SERVICE VALVE
• THERMOSTAT
• ELECTROMAGNETIC CLUTCH
• REFRIGERANT
• ALTERNATOR
5.2.1) COMPRESSOR:-
| Fig.1. Compressor on bus |
• Compressor is the heart of the Air-conditioning system. It is designed to compress the refrigerant vapor. The compressor pulls low pressure – low temperature vapor from the evaporator, compress it, and discharges it to the condenser as a high pressure high temperature vapor .
• It is belt driven from the engine cranckshaft pulley. An EMC clutch engages the compressor shaft. When the voltage is applied to the compressor clutch coil, the magnetic force thus generated locks the clutch plate & the pulley together as one unit & then the compressor shaft is turned with the pulley. Springs in clutch plate & hub assembly automatically moves the plate away from the pulley whn the voltage in the clutch coil is interrupted. This causes the compressor to stop. Here 4 cylinder, v type, piston type compressors are used. The compressor draws in low-pressure, high temperature vaporized refrigerant & compresses it to high pressure. The refrigerant never reaches its liquid state in the compressor.
5.2.2)DISCHARGE SERVICE VALVE:-
• This is a service valve installed on the discharge port of the compressor for serviceman’s testing of the unit. It is also used to check system pressure when charging and discharging the unit
5.2.3)CONDENSER:-
Fig.2.Condenser
• An arrangement of tubing and fins which receives the high pressure – high temperature refrigerant vapor from the compressor ,allowing it to give up its heat to the surrounding ambient air thereby causing condensation of the refrigerant to take place. The refrigerant is now in the form of high pressure liquid which is fed to the liquid receiver tank.
5.2.4) LIQUID RECIEVER TANK:-
• This tank is designed to hold excess liquid in the system so that the unit will have enough refrigerant for all conditions .it is equipped with a fusible safety plug designed to melt between 84 deg c and 90 deg c.
5.2.5) KING VALVE:-
• This valve at the outlet of the receiver is used for liquid charging or discharging of the system .It can also be used for pumping down the refrigerant forcing all the liquid in the system to be collected in the receiver and condenser .
5.2.6) FILTER DRIER:-
The filter drier is designed to remove any moisture and contaminants from the system.
5.2.7) SIGHT GLASS:-
• This is used to determine the level of liquid refrigerant charged in the system. Permanent formation of bubbles through the sight glass in the cooling mode indicates lack of refrigerant charge .
• Water content can be identified by the change of color of the indicator disc.
- Green means dry circuit
Yellow means wet circuit,in this case change filter drier
5.2.8) THERMOSTATIC EXPANSION VALVE:-
• This device controls the flow of refrigerant to the evaporator by maintaining a relatively constant superheat at the end of the evapaporator.
• TXV sensing bulb should be always strapped tightly to the suction outlet pipe and cover using prestige at 4 ‘o clock position .
5.2.9) EVAPORATOR:-
• The part of system where the liquid refrigerant is vapourised to produce cooling.The collection of finned tubes connected together to allow liquid refrigerant to boil and absorb the heat from inside the passenger compartment and circulate dehumidified cool air in to the supply air ducts with the help of evaporator blowers .
5.2.10) SUCTION SERVICE VALVE:-
• This is a service valve installed on the compressor suction port for service man’s testing of unit .it is also used to check system pressures.
5.2.11)THERMOSTAT:-
• A THERMOSTAT IS A TEMPERATURE SENSITIVE DEVICE,WHICH WHEN ACTVATED,SIGNALS THE ELECTRO MAGNETIC COMPRESSOR CLUTCH TO ENGAGE AND DISENGAGE.
5.2.12) ELECTRO MAGNETIC CLUTCH:-
• The electro magnetic clutch controls the operation of the compressor .when engaged the compressor circulates refrigerant and provides cooling
5.2.13) REFRIGERANT:-
• A refrigerant is a substance that services as a moving fluid in an air conditioning unit and circulates through functional parts to produce the cooling effect by absorbing heat.
5.2.14) ALTERNATOR:-
• Alternator is used to give the power supply to the fans of the condenser, evaporator blowers and control circuit
5.3) BASIC COOLING CYCLE:-
• BASIC COOLING CYCLE
•
5.3.1) COOLING CYCLE-1
• When the cooling is on ,the compressor rises the temperature and pressure of the vapor refrigerant and forces it through the surrounding air over the outside of the condenser coil .The condenser fan circulates the surrounding air over the out side of the condenser tube .the tubes have fins designed to improve the transfer of heat from refrigerant gas to the air.The removal of heat causes the refrigerant gas to turn in to liquid ,liquid refrigerant leaves the condenser and flows to the evaporator.
• The refrigerant leaves the condenser and flows through the filter drier where the absorbent keeps the refrigerant clean .the liquid refrigerant then flows through the sight glass to the thermostatic expansion valve (TXV) which reduces the pressure of the liquid and meter the flow of the liquid refrigerant to the evaporator .
5.3.2)COOLING CYCLE -2
• The liquid pressure drops in the expansion valve is accompanied by a drop in temperature ,thus the low temperature liquid that flows into the evaporator tubes is colder than the air that is circulated over the evaporator tubes by the blowers .The evaporator tubes have aluminum fins to increase the heat transfer ,therefore heat is removed from the air circulated over the evaporator. The cold air is circulated through out the bus to maintain the preset temperature.The transfer of heat by the blower air to the low temperature liquid refrigerant cause the liquid to vaporize in evaporator .
• This low temperature low pressure vapor passes through the suction line to the compressor where the cycle repeats it self.
5.4) MAINTENENACE:-
• Check v-belts for adjustment and wear.
• Check v-belt pulleys,bearing and shaft,lubricate if necessary.
• Check condition of air-conditioning housing seals and locks.
• Check function and condition of electric system and thermostat.
• Always follow EHS regulations while working in heights and avoid unsafe acts conditions.
• Check v- belts tension at compressor drive ,adjust if necessary.Renew damaged v-belts,use matched sets.
• Check refrigerant filling at sight glass. Therefore the unit has to run for approx.10-15minutes at a minimum of 1500 rpm. The sight glass has to appear clear and free of bubbles.
• Before servicing the unit ,make sure the ignition switch is in off position .always disconnect the negative battery cable
• Check condenser ,clean if necessary,straighten bend fins; reducing the air flow reduces the heat transfer. To clean dusty condenser use compressed air against the usual flow direction .To remove dirt ,steam cleaning and pressure washing are standard methods for cleaning. Strong caustic soaps and Check refrigeration system for leaks.
• Check refrigeration lines and connection s for tightness,leaks and mountings
• Renew contaminated refrigerant and refrigeration oil.
• Renew filter drier
• Check thermostat expansion valveacids methods should be avoided
• Check function of high and low pressure switches
• Check compressor for leaks ,capacity and mounting.Check oil levels
• Check function of capacity
• Check function bearings of electromagnetic-clutch
5.5) PRECAUTIONS:-.
• Do not use nitrogen cylinder without regulator
• Never smoke near refrigerant system
• Never keep the unit out of operation for long time ( 7 to 10 days)
• DoAlways connect filter drier in line with the arrow indication
• Never run the unit without refrigerant
• Disconnect the batter terminal when any part of the vehicle is being welded
Role in the Departments
My inplant training started in 1st Jan 2011, in BEST Undertakings. During my training Mr.Rao who placed me in different departments of B.E.S & T. Dadar workshop
The main and the major project allotted to me, in B.E.S & T. was to study out the function of each part of buses in detail with the help of practical examples. The main aim of this was that I should gain enough knowledge in the Automobile field. From each and every department of B.E.S & T Undertakings, Dadar Workshop I learned the working, function and overhauling procedure of various parts of the buses, practically as well as theoretically. Working on this field and different aspects altogether was a very good experience for me.
Before my training, my knowledge & attitude of thinking was only restricted to the books, but implant training has cross checked my theoretical knowledge with my practical experience about automobiles.
CONCLUSION
It had been an outright decision for me to get a chance to work in Bruhanmumbai Electrical Supply & Transport, TTC Wadala one of the most prestigious companies existing in India. At the end of my training tenure, it refers this implant training to be as the most exciting, enriching and challenging experience ever in my engineering curriculum. It enabled me with an opportunity to learn under a different environment from which I feel I am really benefited.
Thus I feel that the training, which I underwent at B.E.S & T.Wadala was one of my best experiences of life and I am sure that this would certainly help me in my career.
Thus, I confidently conclude that, this training was the most beneficial and enlightening experience which is bound to help me in my future.
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