Brakes
What do I need to know?
The
purpose of a braking system is to slow and stop your vehicle. It is
controlled by a foot (service brake) pedal and by a hand or parking
brake.
The brakes also allow you to make an emergency stop if you need to. It
is therefore important that you ensure that your braking system is
maintained and operating at optimum levels. It is a legal requirement
that your braking system performs as intended and your brakes will be
tested as part of your MOT.
The
real danger is that because the loss of performance takes place over a
significant period of time, the driver makes subconscious compensation
for the gradual deterioration, not fully aware of how dangerous the
braking system has become. The importance of having your car’s brakes
checked and tested by a qualified technician cannot be over –
emphasised.
At Hylton our technicians are highly experienced
and fully trained to spot those early danger signs. But understanding
how your brakes work is also worthwhile and can help spot some of the
early danger signs. However, if in doubt ALWAYS bring your car to your
nearest Hylton branch.
When should I change my brakes?
Manufacturers
recommend that brake pads should be replaced if the pad friction
material has worn down to a thickness of 3 millimeters. See guide
below.
Brake
disc thickness should be measured and replaced if they measure at or
below the manufacturer’s safe minimum thickness specification, Hylton
also recommends that brake discs or drums are replaced in axle sets.
Replacing one brake disc on drum could cause an imbalanced braking
performance that could lead to further premature wear.
How do brakes work?
When
you step on your brake pedal, the leverage pushes a small piston inside
the master cylinder, which in turn is filled with brake fluid. The
action of the moving piston inside the cylinder pumps the fluid through
small pipes to each wheel where brake linings are forced against either
the brake disc or the brake drum. This process is called hydraulic
action.
Disc Brakes
A disc brake
system consists of a brake disc, a brake calliper and brake pads. When
the brake pedal is applied, pressurised hydraulic fluid squeezes the
brake pad friction material against the surface of the rotating brake
disc. The result of this contact produces friction which enables the
vehicle to slow down or stop.
ABS System
The
anti-lock braking system (ABS) works by limiting applying and releasing
the pressure to any wheel that decelerates too quickly. This allows
maximum stopping force to be applied without the brakes locking-up and
the car skidding.
Parking Brake
The
parking or hand brake is a lever mechanism that is applied to hold a
vehicle in a parked position. It activates braking components at the
rear of the vehicle’s braking system.
Drum Brakes
A
drum brake system consists of hydraulic wheel cylinders, brake shoes
and a brake drum. When the brake pedal is applied the two curved brake
shoes, which have a friction material lining are forced by hydraulic
wheel cylinders against the inner surface of a rotating brake drum. The
result of this contact produces friction which enables the vehicle to
slow or stop
What Can Go Wrong
Renewing
the pads or shoes as they wear is the most common requirement and
frequent inspections are recommended. If the lining material wears
excessively, it’s not only extremely dangerous but inevitably other
components become damaged calling for costly replacements. Fluid leaks
are the second most common fault and can result in total brake failure.
The
most common maintenance requirement within the braking system is
renewing the brake pads or shoes. These have a heat resistant friction
material which wears down due to being clamped against the brake disc
or pushed against the brake shoe when the braked are engaged. Due to
usage and driving conditions wear to these components is unpredictable
and frequent checks are recommended.
Fluid leaks are the
second most common fault – caused by worn seals on the wheel cylinders,
perished flexible brake hoses or corroded metal brake pipes. Not only
can fluid loss result in total brake failure, leaks in the wheel
cylinder will contaminate brake linings.
Why change your brake fluid?
Brake
fluid is used in braking systems and is designed to have a high boiling
point to withstand the high temperatures generated by friction in the
braking system
Brake fluid deteriorates over time.
It’s hygroscopic – this means it absorbs moisture
Moisture can in turn corrode brake seals
Fluid contaminated by moisture will get hot enough to boil your brake fluid
When brake fluid boils, compressible vapour forms in the braking system causing the pedal to feel soft or not work at all
Brake
fluid contamination has become so much of a concern that all major
vehicle manufacturers recommend changing at least every 2 years.
Failure to change your vehicles brake fluid can result in extremely costly repairs