Tractors are composed of engine, transmission system, walking system, direction system, hydraulic system, power output system, electrics and meters, operation system and dragging system, etc.

Wheel tractors can be catagorized as small size tractor, medium size tractor, big size tractor and hyper size tractor.

Small size tractor will have a power of 11KW to 18.4KW (15-25 HP).

Medium size tractor will have a power of 18.4KW to 33KW (25-45 HP).

Big size tractor will have a power of 33KW to 62.5KW (45-85 HP).

Hyper size tractor will have a power more than 62.5KW (more than 85 HP), and up to 335.6KW (450HP).