GEAR BOX And Types

Gear Box

Manual transmission:

1. Sliding Mesh Gearbox

2. Constant Mesh Gearbox

3. Synchromesh Gearbox

Location:  Located between the clutch and final drive sprocket.

2. Constant mesh type with dog clutches.

Working:

All the gears on the main axle are in constant mesh with gears on the drive axle. All gears will be rotating in any gear. The slide of the of the gears is provided with a protrusion called the dog clutch. When the shift pedal depressed or lifted, a slide gear is moved sideways to engage with a neighboring idle gear and thus engine power is transmitted.

The sliding mesh gear box give max mechanical efficiency but has some disadvantages like gear noise, rough in operation and required skill in change of gear. The constant mesh gear box have helical gears for silent operation the main axle is splined and having gear mounted on bushes these gears are in constant mesh with lay shaft gears a thrust washer fitted between gear and casing to bear axial thrust.

The sliding dog is slide by selector fork to left or right to obtain the required gear ratio these dogs have internal splines and so can move over spline main shaft.

Sliding Mesh Gearbox:

 

Synchromesh Gearbox:

 

Although a constant mesh gearbox has improvement over sliding mesh gearbox but gear can not be engaged only by gear level as fast as possible this gives noise and jerky engagement, synchromesh nearly equal that is speed of main axle gear and dog must be nearly the same when the dog clutch being engaged with any of main axle gear.
It consists of toothed ring or sleeve with internal splines and internal cone which is part of toothed ring, a spring loaded ball to maintain pressure on toothed ring and a external cone which is taper to mesh the surface of internal cone dogs are formed of the cone.