Subject: Automobile Engineering

Topic: Transmission Systems, Live Axle & Differential

Difficulty: High

In the Constant Mesh Gear Box, all the gears are in constant mesh with the corresponding gears on the layshaft. The gears on the main shaft which is splined, are free. The dog clutches are provided which are free to slide on the main shaft. The gears on the layshaft are, however, fixed.

a) First gear: To obtain the first (low) gear, the Dog clutch D2 moves towards by means of gear shift lever, it teeth are engaged with teeth on low gear M1.

b) Second gear: Similarly , when dog clutch is moved right & mesh with teeth on M2 gear, a second gear is obtained.

c) Reverse gear: When dog clutch D2, is moved right & mesh with teeth on M3 gear a reverse gear is obtained. The direction of rotation is change by gear I.

In this gear box, because of all gear are in constant |mesh, they are safe from being damage & unpleasant grinding sound does not occur while engage & disengaged.
In this gear box, skillful handling is necessary by drive so that speed of locking dogs & respective gear on main shaft remains same to effect a clash free change. For obtaining speed double declutching is necessary.