PROJECT REPORTMAINTANCES OF BUSES

PRESENTATION OF ENGINEERING DEPARTMENT

BY SHYAMVEER SINGH RAJAWAT

RAJASTHAN STATE ROAD TRANSPORT CORPORATIN

Rajasthan State Road Transport Corporation(RSRTC) is the largest provider of intercity bus transportation in the Indian state Rajasthan.It is headquartered in Jaipur, Rajasthan.

HISTORYThe corporation has been established by Government of Rajasthan on 1 October 1964 under the Road Transport Act 1950 with the objective of providing economic, adequate, punctual and efficient services to the travelling public in the state.

Present statusToday RSRTC has entered into 50th year of business, since its inception and is committed to providing high quality bus services, consistently and constantly improving the services for the satisfaction of the passengers. To fullfill the commitment, RSRTC has incorporated Ordinary, Express, Deluxe, A.G. Gandhi Rath, A.C., A.G. Sleeper, Volvo-Mercedes, Volvo-Pantry, Volvo-LCD, Volvo-LCD-Pantry bus services in fleet for all category of passengers. It has 4,530 buses in its fleet and 56 depots across the state and 3 depots outside the state.

STRUCTURE OF CORPORATION HEADQUARTERS

Chairman

Managing directorExecutive Director

General Manager( Store & Purchase )

General Manager ( Tyre )

General Manager( Bus Body/Accident &

Training )

General manager( Quality Cantrol )

Chief Production Manager( Jaipur )

DEPOT WORKSHOPZonal Manager

Chief Manager

Manager Operation

JEN ( Diesel ) JEN ( Tyre )

Shift Incharge( Night) JEN

Time Keeper Store Inspector

Shift Incharge(day) JEN

Information OfRajasthan State Road Transport

Corporation 1. Total vehicles 4530

2. Total on cont. vehicles 219

3. Total no. of depot / workshop 56

4. Diedel kmpl 2013-14 up to feb 2014 4.90

5. Fleet ut. % 95%

6. Vehicle ut. 390

7. Vechicle uses per vechicle per day (k.m.) 390

Make wise Fleet CompositionAshok leyland

Tata motors

Volvo

Eicher

Total

Total midi buses

Mercides benz

3040

1197

40

15

10

228

4530

Main activities in depot workshops

• Daily washing & cleaning • Routine check up of vehicles 2000 km • Weekly check up of vehicles• Oil change of vehicles • Heavy docking work (40,000 kms. Wheel

maintainance)• 80,000 km docking• Minor accident work

CENTRAL WORKSHOP

FUNCTIONING OF CENTRAL WORKSHOP

There are three central workshops in RSRTC for reconditioning of buses and major overhauling of the assemblies :

1. Central workshop, Ajmer, for Leyland vehicles;2. Central workshop, Jodhpur, for TATA vehicles;3. Central workshop, Jaipur, for Leyland vehicles.

Each Central workshop is headed by chief production manager and assisted by the

following officers

1. Production manager to look after the complete mechanical work.

2. Administrative officer to look after the establishment work of the staff .

3. Account officer to look after account work .

The reconditioning and overhauling work of the major assemblies following main sections are there. These section are headed by one Junior Engineer / Asst. Mechanical engineer.

1.Chassis section 2.Body section 3.Engine reconditioning section4. Major and minor assemblies reconditioning

section5. Fuel injector pump reconditioning section6. Electrical assemblies reconditioning section7. Receipt and dispatch section

Central workshop are responsible to provide following major and minor assemblies to the depots as and when required

1.Engine assemblies.2. Rear axle assemblies.3. Gear box.4. Self starter.5. Terbo charger.6. Stearing assemblies.7. Front axle assemblies. 8. Spring assemblies.9. Alternator assemblies.10. Related to brake assemlies

CENTRAL WORKSHOP JAIPUR

• Bharatpur• Lohagarh• Alwar• Matysayangar• Tizara• Hindaun• Dholpur

• Jaipur • Kotputali• Dausa• Vaishalinagar• Shahpura• Karoli• Deluxe

Besides, reconditioning of vehicles the condemnation work of all the vehicles is also carried out at central workshops level by the following committee :

o Executive director (engineering)o Concerned CPMo Concerned Zonal managero Concerned chief managero Account officer of CWS

Bus manufacturing had its earliest origins in carriage building. Other bus manufacturers had their origins in truck manufacturing. Historically, bus chassis were shared between truck designs, but in later years specific bus chassis have been developed, and the midi bus saw the introduction of a lighter weight bus chassis than normal trucks.

History of bus manufacturing

Types of constructionThere are three basic types of bus manufacturer:

1. Chassis manufacturer - builds the under frame in a body-on-frame type construction 2. Body manufacturer - builds the coachwork a body-on-frame type construction 3. Integral manufacturer - builds entire buses, often using no under frame at all

ChassisThe chassis combines:1. A structural under frame2. Engine and radiator3. Gearbox and transmission4. Wheels ,axles and suspension5. Dashboard and steering wheel and driver's seat

Rear Axle AssemblyThe rear axle assembly is used on rear-wheel drive vehicles. This assembly is the final leg of the drive train. It is often called the final drive or rear end. The rear axle assembly is often mistakenly called the differential . The differential is only part of the rear axle assembly. The basic design of rear axle assemblies has been adopted by all manufacturers for many years. There are several variations, but all operate according to the same basic principles. The major difference between rear axle assemblies depends on whether the vehicle has solid-axle rear suspension or independent rear suspension

Rear Axle Assembly

Solid-axle rear suspension incorporates rigid and non flexing drive axles and axle tubes; both wheels move as one solid unit in response to bumps and potholes. Independent rear suspension incorporates jointed drive axles (no axle tubes) that allow for flexibility and independent axle movement. This report is designed to identify and explain the construction and operation of various rear axle assemblies. The material in this chapter provides a basis for understanding how to properly troubleshoot and repair rear axle assemblies.

Crown wheel

Construction and Operation Overview The rear axle assembly includes the differential assembly, the rear drive axles, and the rear axle housing.

Rear axle assemblies are subjected to heavy loads from the engine and road. They are ruggedly constructed and seldom fail. The most common rear end failures are axle bearing failures.

In a rear axle assembly, engine power enters the drive pinion gear from the drive shaft assembly and differential pinion yoke/flange.

The drive pinion gear, which is in mesh with the ring gear, causes the ring gear to turn. The interaction of the ring and drive pinion gears turns the power flow at a 90° angle.

The difference in the number of teeth on the ring and pinion gears causes a reduction gear ratio. This reduces turning speed, while increasing torque. Power from the ring gear flows through the differential case, spider gears, and side gears to the drive axles. The drive axles transfer power from the differential assembly to the rear wheels. The bearings and rear axle housing are key components of the rear axle assembly. They are designed to support and align the differential assembly and the drive axles. Notice that the bearings and axle housing are large, heavy-duty parts. This is to ensure they will stand up under hard usage. Seals and gaskets are also very important to the operation of the rear axle assembly. Seals are used at the differential pinion yoke/flange and at the outer drive axles. Gaskets are used at housing interfaces, such as between the differential cover and the housing, to provide a tight seal from the outside.

Differential Assembly

The first, and most obvious, is to redirect the power flow to drive the rear wheels. The power flow must make a 90° turn between the drive shaft assembly and the rear wheels. This is accomplished in the differential assembly by the drive pinion and ring gears.

The differential assembly in a rear-wheel drive vehicle has three functions.

The second function of the differential assembly is to multiply engine power, reducing speed at the output in the process. If there were no gear reduction (1:1 gear ratio), the vehicle would accelerate very slowly. In some cases, the engine would be unable to move the vehicle. At the very least, gas mileage would be harmed, since the engine would not reach its most efficient rpm range. For this reason, the ring and drive pinion assembly, bydesign, provides a reduced speed at its output. The reduction is between 2:1 and about 5:1, depending on the engine size, vehicle weight, and intended use of the vehicle.

The third function of the differential assembly is to allow the vehicle to make turns. If the assembly did not make allowances for the different speeds of the rear wheels during turns, one tire would lose traction with the ground as the vehicle turned corners. The differential assembly allows the vehicle to make smooth turns.

Differential Drive Gears

The differential drive gears also called the ring and pinion gear set, consist of the ring and drive pinion gears. These hypoid gears redirect power flow by 90° and multiply engine power.

The number of teeth in the ring gear compared to the number of teeth in the drive pinion gear sets the rear axle ratio. The ring gear has 42 teeth and the pinion gear has 7 teeth, the ratio is 42:7, or 6:1 .

Pinion gear

Crown wheel

The ring gear always has more teeth than the drive pinion gear. Rear axle ratios can always be determined by dividing the number of teeth on the ring gear by the number of teeth on the drive pinion gear.

The drive pinion gear is a hardened-steel gear with an integral shaft, It is machined to mesh with and rotate the ring gear.

The end of the shaft opposite the gear has external splines that fit the internal splines of the differential pinion yoke/flange. The gear is supported by two tapered roller bearings, called pinion bearings.The rear pinion bearing is pressed onto the drivepinion gear shaft at the gear end. The front pinion bearing is often a slip fit on the smaller end of the shaft.

The outer races, or bearing cups, of both bearings are pressed into the rear axle housing. Either a solid spacer or a collapsible spacer crush is used to set the pinion bearing preload.

The collapsible spacer is designed to be slightly compressed when the drive pinion gear is installed in the rear axle housing.

The spacer maintains a mild pressure between the front and rear pinion bearings, making it possible to accurately adjust the bearing preload.

The differential pinion yoke/flange has internal splines that fit the external splines on the drive pinion gear shaft. The rear of the yoke/flange.

it fits into the rear axle housing,is machined smooth. This is the sealing surface for the pinion seal. The yoke/flange is held to the drive pinion gear shaft by a large nut and washer that threads onto the shaft.

This nut is a type known as a jam nut. The top threads of the nut are deformed to tightly grip the threads on the drive pinion gear shaft. This is an interference fit. Tightening the nut also adjusts the pinion bearing preload.