Gear Box / gearbox Problems and Defects

How A Gear box (Transmission) works? What’s Gear Ratio?


 | 6 minutes read

Gear Box Working Principle:

A Gear Box is an assembly consisting of various gears, synchronizing sleeves, and a gear-shifting mechanism fitted inside a metal housing. The metal housing, usually made of aluminum/iron casting, accommodates all the gears in it. The gearbox is a part of the ‘transmission’ system as the gears play an important role in transmitting the engine power to the wheels.

5-Speed Gear Box diagram
5-Speed Gear Box diagram

What is Transmission?

All the drive-train components that help transmit the engine power to the wheels are a part of the ‘Transmission’ system. Of which the gearbox is an integral part. These components include the clutch, gearbox, couplings, propeller shaft, axle shafts, and differential. In general, the term 'Transmission' usually refers to the car’s gear box. Some car designs integrate the gear box and differential assembly into a single unit called ‘Transmission’ or 'Trans-Axle.'

What is the Gear Ratio?

The gear ratio is the ratio between the input and output gears. The driving gear and driven gears in a gear box define the gear ratios. The input gears get the engine's drive, and they rotate the output gears, which, in turn, drive the wheels. The ratio of the number of rotations of output gear to the number of rotations of input gear is called the Gear Ratio.

The Gear Ratio can also be obtained by the following formula:

Gear Ratio = No. of teeth of output gear / no. of teeth of the input gear

For e.g., If no. of gears on input (driving) gear = 30, no. of gears on output (driven) gear = 105

Then, the Gear ratio = 105/30 = 3.5:1 because to rotate the output (driven) gear by 1 rotation, you need to turn the input (driving) gear by 3.5 rotations.

Don't miss out on Automotive Knowledge