The Transmission is the mechanism for getting power from the engine to the wheels or tracks, and thus to the ground to propel the vehicle or machine forward or backwards.
Using the principle of mechanical advantage, transmissions provide a speed-torque conversion (commonly known as "gear reduction" or "speed reduction") from a higher speed motor to a slower but more forceful output.
Thee are various types of Transmission used in tractors and plant;
- Mechanical via clutch and Gear box assembly of Manual gearbox and Automatic gearbox types.
- Via a Torque-converter and Gearbox (also known as Hydrodynamic)
- Hydraulic - generally called hydrostatic
- Continuously Variable transmission CVT using twin tapered pulleys and a belt drive.
- Electro mechanical - Generator mounted on the engine and DC motors in the wheel assemblies, (Used in large earthmovers and Dump trucks for mining with massive torque requirements)
The drive generally the goes via a Differential to each wheel, often being further geared down for low speed high torque by use of reduction or epicyclic hubs.
Transmissions often change the direction of the rotational forces as well. The use of a beveled gearbox allows the direction to turn 90 degrees, thus engines can be mounted sideways on in some applications.
- Gearbox - several different types available
- Propshaft (Propellor shaft)
- Reduction hub
- Transfer box
- Power Take Off