Braking Systems
ANTI-LOCK BRAKING SYSTEM (ABS)
A vehicle fitted with an anti-lock braking system is designed to allow you to stop safely and maintain steering control when you have to stop in an emergency. It also improves your vehicles safety while braking heavily.
When driving a vehicle fitted with an anti-lock braking system you should apply firm continuous pressure to the brake pedal when braking in an emergency.
‘Pumping’ the brake pedal in a vehicle fitted with an anti-lock braking system, can cause it to have reduced effectiveness.
When a vehicle is fitted with an anti-lock braking system you should check that it’s working properly before every journey.
When driving a vehicle fitted with an anti-lock braking system there is no need to alter the way you brake when braking normally.
The anti-lock braking system (ABS) warning light will turn off when road speed is at 6mph, 10km/h or more.
AIR PRESSURE
If a vehicle is fitted with air brakes and you start the engine and a brake warning light shows it means, there is low air pressure.
When starting the engine or stationery and the brake air pressure warning light is showing you must keep the parking brake on because the service brake may not stop you.
When starting a journey in frosty weather the likely cause of low air brake pressure is frozen moisture in the storage tanks.
Moisture drawn in with the air may freeze and cause a blockage which could prevent air pressure from building up in an air-brake system in frosty weather.
If the air pressure warning light comes on whilst you’re driving, you should stop and get help without delay.
When an air pressure warning device activates you should stop and have the fault put right.
When you’re about to drive an unfamiliar vehicle, you should find out whether you need to drain the system manually if you think there may be moisture in the air brake reservoir.
Coasting downhill can seriously affect the air brakes.
ENDURANCE BRAKE (RETARDER)
An endurance brake (retarder) is especially useful and should be used on long downhill slopes, this will also prevent the brakes from overheating.
When driving down a snow-covered hill/ slippery road you should take extra care when using an independent endurance brake (retarder) because the drive wheels could lock.
The brake linings are the component that will last longer when you use the retarder.
ESCAPE LANES
You would see an escape lane down a steep hill.
You would use an escape lane when your brakes have failed.
USES OF THE BRAKES
The blue coloured band on the rev counter makes the best use of engine braking.
The most powerful brake on the bus is the service brake.
When making a short stop facing uphill you should apply the parking brake after stopping.
When moving off in a vehicle that has automatic transmission, you must put your foot on the footbrake before you select ‘D’ (drive).
When driving a vehicle that is fully loaded and dealing with bends you should be braking when driving in a straight line.
After driving through a flood, you should drive in a low gear with the footbrake lightly applied.
The advantage of progressive braking is improved passenger safety and comfort.
If a large vehicle is overtaking you on a two-lane motorway and they do not have the speed to get past you should be prepared to reduce your speed.
AIR ASSISTED HYDRAULIC BRAKING SYSTEM/HYDRAULIC BRAKING SYSTEM
Before driving a vehicle fitted with hydraulic brakes you should check the hydraulic brake fluid level.
If a vehicle is fitted with hydraulic brakes and the brake pedal goes down too far when its pressed it is because there isn’t enough fluid in the braking system.
When you're about to drive a vehicle fitted with air assisted hydraulic brakes, if the brake pedal feels hard when you press it, the brake system has a loss vacuum.
A vehicle fitted with air assisted hydraulic brakes a buzzer or light would warn you that there isn’t enough air in the system.
BRAKE FADE
Brake fade occurs when the brakes get too hot, it causes loss of effectiveness of the brakes.
Continuous use of the brakes can cause brake fade.
Brake fade would most likely happen on a long downhill gradient.
To prevent brake fade, use the endurance brake (retarder).