Subject: Automobile Engineering

Topic: Transmission Systems, Live Axle & Differential

Difficulty: Low

Fig: 4.1 shows the various parts of a sliding mesh gear box. It consists of a clutch shaft, counter shaft & main shaft. The clutch shaft has one gear whereas the counter shaft has four gears . All four gears an integral part of the counter shaft. The main shaft has two gears that can slide horizontally along the splines of the main shaft. There is no such spline arrangement in the counter shaft. therefore, the gears cannot move along it.

a)FirstGear:
The clutch is disengaged so that gear box has shaft & layshaft stop rotating then move the gear C moved toward left to mesh with gear M on layshaft by selector mechanism. Now engaged the clutch.
b) Second speed Gear:
By operating gear shift lever, Gear B on the main shaft should be mesh with gear L on the lay shaft.
c) Third or top gear:
By operating gear shift mechanism, the second gear on the main shaft & lay shaft demeshed . Then gear B moves towards left which mesh directly with gear A. The main shaft turn with clutch shaft & a gear ratio of 1:1 is obtained.
d) Reverse Gear:
By operating gear shift mechanism, the top gear is disengaged first & move the gear C on the main shaft toward right axially to mesh with an intermediate gear (idler gear) mounted on another shaft. On gear R, a reverse gear is obtained. This idler gear change the direction of rotation of main shaft. This reverse the rotation of wheels so that the vehicle backs