Automobile Gearbox: Definition, Diagram, Types, Parts, Pdf

What is a Gearbox?

• An automobile gearbox Is an assemblage of gears and shafts, which is used to control the output speed & torque of a machine/vehicle.

• The engine provides a fixed speed for a certain amount of power & If it is directly coupled to the output shaft then it will give the fixed velocity of the vehicle.

• In the case of a vehicle running on a straight road with a higher speed, It doesn’t require a higher amount of torque because of the momentum of the vehicle. Hence it can run with less amount of torque.

• In Another case, when the vehicle is climbing the heel, It requires a higher amount of torque.

• Therefore the power transmission depends upon the Running condition of the vehicle.

• The vehicle also requires neutral condition even the engine is started

• Therefore gearbox is needed for a vehicle to control output speed & torque.

• It is located between the clutch & propeller shaft

• As per the need of the vehicle, different speeds or torque we can achieve with the help of a gearbox.

• For Example – In the case of the tractor which requires higher torque & lower speed hence reduction ratio is higher.

• While in the case of Racing vehicles which require higher speeds with less torque. In this case reduction ratio is lower.

• It has N number of speed steps & one reverse step.

Gearbox diagram:

Working principle:

The gearbox works on the following principle:-

• When Smaller gear meshes with Larger gear, low speed & high torque will obtain at output shaft.
• When larger gear meshes with Smaller gear, high speed & low torque will obtain at output shaft.

Construction:

The gearbox consists of an engine shaft, Lay shaft, Output shaft (Externally Splined), Clutch gear, Gears (1, 2, 3, 4, A, B, C), Idler gear etc.

Necessity/Significance of gearbox:

1. To Control Output Torque.
2. To Control Output Speed.
3. To Achieve Neutral Position.
4. To Achieve Reverse Gear transmission.

Types of automobile gearbox:

A) Manual Transmission:-

1. Sliding Mesh gearbox
2. Constant Mesh Gearbox
3. Synchromesh Gearbox

B) Automatic Transmission:-

1. Torque Converter
2. Epicyclic Gear Transmission  

Read also:

• Automobile Braking System & its Types