Automobile Gearbox: Definition, Diagram, Definition, Necessity, Function, Working principle, Construction, Parts, Types [with Pdf]

What is gearbox?

  • Automobile Gearbox is an assemblage of gears and Shaft, which is use to control output speed & torque of machine/vehicle.
  • The engine provides fixed speed for a certain amount of power & If it is directly coupled to output shaft then it will give fixed velocity of vehicle.
  • In case of vehicle running on straight road with higher speed, It doesn’t require higher amount of torque because of momentum of vehicle. Hence it can run with less amount of torque.
  • In Another case, when the vehicle is climbing the heel , It requires higher amount of torque.
  • Therefore the power transmission depends upon the Running condition of the vehicle.
  • Vehicle also requires neutral condition even the engine is started
  • Therefore gearbox is need of vehicle to control output speed & torque.
  • It is located between the clutch & propeller shaft
  • As per need of vehicle, different speed or torque we can achieve with the help of gearbox.
  • For Example – In case of tractor which requires higher torque & lower speed hence reduction ratio is higher.
  • While in case of Racing vehicles which requires higher speed with less torque. In this case reduction ratio is lower.
  • It has N number of speed steps & one reverse step.

Gearbox diagram:-

automobile gearbox

Gearbox 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.

Gearbox Construction:-

Gearbox consists of 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:-

  • To Control Output Torque.
  • To Control Output Speed.
  • To Achieve Neutral Position.
  • To Achieve Reverse Gear transmission.

Classification 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  

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