TORQUE AND POWER
TO properly understand how a diff works you need to understand power and torque, as well as how they relate to one another.
Torque can be defined as a force that has a tendency to rotate an object around its axis. Torque in automotive applications is measured in Newton-metres (Nm). 1Nm is the torque on an axis that results from the force of one Newton (about 0.1kg) on an arm 1m long.
Power is all about movement. The unit for measuring power is the Watt (W).
One Watt is one joule per second. For our purposes, one joule equals 1Nm. Engines power is measured in kw (kilowatt): 1kw = 1000W.
If you look at the simple equation below you can see there is a relationship between torque, power and rpm:
Exposed rear diff of a Range Rover Sport.