There are three types of brakes on large goods vehicles:
The service brake is operated by the foot control. It is used to control the speed of the vehicle and to bring it to a safe stop.
The parking brake or handbrake must always be applied when you leave the vehicle.
A secondary brake works on less wheels which means it has a reduced level of effectiveness. If your service brake fails your secondary brake can be used in conjunction with the parking brake to slow and eventually stop the vehicle
Use the vehicles’ gears to help in the braking process when descending hills, especially if the vehicle is loaded.
You should use a low gear which will increase the effectiveness of the engine braking. The revs should ideally be kept in the blue band on your rev counter for maximum braking efficiency.
THREE LINE SYSTEM
TWO LINE SYSTEM
A combination of sharp braking and excessive steering can cause your vehicle to become unstable. Jack-knifing is more likely to occur when the vehicle is empty, unladen or not travelling in a straight line.
Severe braking or selection of a gear too low for your road speed can cause the tractor unit to be pushed by the semi-trailer pivoting around the coupling (fifth wheel).