Pimpri Chinchwad Polytechnic Nigdi Pune Program : Mechanical Engineering Course: Automobile Engineering

CO: Describe construction &working of various automobile systems. CHAPTER 2 Transmission System CO: Describe construction &working of various automobile systems.

Need Of Transmission System It consist of a clutch, a gearbox, a propeller shaft and differential. Function: To engaged or disengaged the power from engine to transmission system, to transmit the torque and to distribute the final torque equally between the driving wheels.

Clutch Function of the Clutch  is to transmitting the torque from the engine to the drive train. Smoothly deliver the power from the engine to enable smooth vehicle movement. Perform quietly and to reduce drive-related vibration.

Clutch Single Clutch and Multiple Disk Clutch. Basically, theclutch needs three parts. These are the engine flywheel, a friction disc called the clutch plate and a pressure plate. When the engine is running and the flywheel is rotating, the pressure plate also rotates as the pressure plate is attached to the flywheel.

single plate clutch

Diaphragm Spring Clutch Diaphragm-spring clutch has similar construction to that of the multi-coil spring unit, but it uses a single dished diaphragm-type spring to apply the clamping thrust. This spring also serves as part of the release mechanism.

Diaphragm Spring Clutch

Gear Box An automobile requires high torque when climbing hills and when starting, even though they are performed at low speeds. On other hand, when running at high speeds on level roads, high torque is not required because of momentum.  So requirement of a device is occur, which can change the vehicle’s torque and its speed according to road condition or when the driver need. This device is known as transmission(Gear Box) box.

Gear Box Function of transmission box (gear box) in automobile: The transmission box which is also known as the gear box is the second element of the power train in an automobile. It is used to change the speed and torque of vehicle according to variety of road and load condition. Transmission box change the engine speed into torque when climbing hills and when the vehicle required. Sometimes it is known as torque converter. Main functions of a gear box is as follow:

Gear Box 1. Provide the torque needed to move the vehicle under a variety of road and load conditions. It does this by changing the gear ratio between the engine crankshaft and vehicle drive wheels. 2. Be shifted into reverse so the vehicle can move backward. 3. Be shifted into neutral for starting the engine.

Constant Mesh Gearbox:   In constant mesh gear box all the gears are always in mesh and the engagement between the gears which are freely rotating on the transmission main shaft and the transmission main shaft is effected by moving the dog clutches. Dog clutch is shown in very left in the photo.

Constant Mesh Gearbox:

Synchromesh Gearbox This is the provision of synchromesh device which avoids the necessity of double declutching. The parts which ultimately are to be engaged are first brought into frictional contact which equalizes their speed, after which these may be engaged smoothly.

Synchromesh Gearbox

Overdrive Overdrive is the highest gear in the transmission. Overdrive allows the engine to operate at a lower RPM for a given road speed. This allows the vehicle to achieve better fuel efficiency, and often quikr operation on the highway.

Overdrive

Transfer case A transfer case is a part of the drivetrain of four-wheel-drive, all-wheel-drive, and other multiple powered axle vehicles. The transfer case transfers power from the transmission to the front and rear axles by means of drive shafts. It also synchronizes the difference between the rotation of the front and rear wheels, and may contain one or more sets of low range gears for off-road use.

Transfer case

Two Wheeler Gear Box Most manual transmission two-wheelers use a sequential gearbox. Most modern motorcycles (except scooters) change gears (of which they increasingly have five or six) by foot lever. On a typical motorcycle either first or second gear can be directly selected from neutral, but higher gears may only be accessed in order – it is not possible to shift from second gear to fourth gear without shifting through third gear.

Two Wheeler Gear Box A five-speed of this configuration would be known as "one down, four up" because of the placement of the gears with relation to neutral. Neutral is to be found "half a click" away from first and second gears, so shifting directly between the two gears can be made in a single movement.

Two Wheeler Gear Box