What is the purpose of using a vehicle's Jake brake?

The purpose of using a vehicle's Jake brake, also known as an engine brake, is to assist in slowing down the truck without using the service brakes. This system works by altering the operation of the engine's exhaust valves. When engaged, the Jake brake releases compressed air from the engine's cylinders, which creates resistance in the engine and helps slow the vehicle.

This is particularly useful in maintaining control and reducing the wear on the service brakes, especially during long descents or when you need to decelerate without frequently using the foot brakes. Using the Jake brake effectively can improve safety and reduce brake fade, making it a valuable feature in heavy-duty trucking.