Topic

BRAKING SYSTEMS

VEHICLE BRAKING SYSTEMS

There are three types of brakes on large goods vehicles:

Service Brake

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.

Parking Brake

The parking brake or handbrake must always be applied when you leave the vehicle.

Secondary Brake

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

ANTI-LOCKING BRAKING SYSTEM

Just as the wheels are about to lock, the sensor control releases the brakes and immediately applies them again enabling the driver to steer whilst braking

If you’re driving a vehicle with anti-lock brakes and you feel the vehicle beginning to skid, you should keep your foot firmly on the brake pedal until the vehicle stops. This will allow the system to work

DRIVING DOWN HILLS

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.

AVOIDING BRAKE FADE

Continual use of the brakes could cause them to fade. Which makes them less effective.

Make sure that you’re in the correct gear before you negotiate downhill stretches of road.

A low gear will assist with braking and help prevent the vehicle gaining momentum as you negotiate the descent.

AIR LINES

A two-line system consists of the:

Emergency line – red in colour
Service line – yellow in colour

It’s important to understand how to safely connecting brake systems and mixing two and three line systems

TIP

When connecting three lines to a two-line trailer the blue line, is the one that should NOT be connected to the trailer.

THREE LINE SYSTEM

SERVICE LINE

EMERGENCY LINE

AUXILIARY LINE

TWO LINE SYSTEM

SERVICE LINE

EMERGENCY LINE

JACK KNIFING

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).