Basic part time 4WD layout

Goal: To keep moving in off-road environments.

In addition to engine and transmission a 4WD will need a "transfer case". Transfer case because it transfers additional rotational force "torque" to the front axle.

A lever activated by the driver will connect both drive shafts solidly when the additional torque is needed.

Part time 4WD layout

Most of the time this 4WD system will stay in 2WD. Part of the time it can be used in 4WD. That's why this system is called "part time 4WD"

The use of 4WD is limited to gravel roads and off-road. The permanent high traction of paved roads will not allow the use of part time 4WD.

Reason: The solidly linked drive shafts do not accomodate the need of front and rear axle for different rpm input.

Why axles and wheels have a need for individual rpm