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Car MOT Manual 2012 onwards


3.3 All types of braking systems

Information
Vehicles with a smooth brake pedal pad which from manufacture did not incorporate grooves or the fitting of an anti-slip material should not be subject to rejection.

The provision of a pedal rubber which is itself an anti-slip material is not regarded as a reason for rejection if the design pattern is worn smooth
Method of Inspection
A. All types of braking systems

1. Check:
a. the condition of the brake pedal and brake actuating linkage e.g., to remote master cylinders
b. the anti-slip face on the pedal pad
c. the security of the pedal pad to the pedal and the pedal to operating lever
d. the condition of the pedal bearing or pivot
e. for chafed rods or levers
f. for frayed or knotted cables
g. for any corroded or damaged rod, lever or linkage. Wear in eyes of relay levers, clevis joints, stationary pins or pivots
h. for abnormal movement of levers, indicating maladjustment or excessive wear.

2. Examine the vehicle structure near actuating linkage and mounting points for excessive corrosion, distortion and fracture.

3. On vehicles first used on or after 1 January 1968, check that a brake is applied to all the wheels this may need to be substantiated during the brake test.

4. Depress the pedal and check for fouling on parts of the vehicle.

5. Depress the pedal fully and check the position of the pad relative to the floor.

6. Check the service brake control for any inappropriate repair or modification.
Reason for Rejection
1.
a. The pedal or actuating linkage fractured, excessively corroded or functionally incomplete
b. the anti-slip provision on the brake pedal pad is missing, incomplete, loose or worn smooth
c. a pedal pad or operating lever not secure to the pedal
d. excessive side movement of the pedal at right angles to its normal movement indicating a badly worn pedal bearing or pivot
e. a brake rod or lever reduced in thickness by more than 1/3rd
f. a brake cable:
knotted or,
with wires broken so that the cable is weakened significantly
g. serious weakening of any part due to excessive wear, damage or corrosion
h. abnormal movement of levers indicating maladjustment or excessive wear.

2. Deliberate modification which significantly reduces the original strength, excessive corrosion, severe distortion, a fracture or an inadequate repair of a load bearing member, its supporting structure or supporting panelling within 30cm of an actuating linkage mounting point, that is, within a prescribed area see Appendix C.

3. On vehicles first used on or after 1 January 1968 a brake is not applied to all the wheels.

4. The pedal is fouling parts of the vehicle so that free movement of the pedal is obstructed.

5. When the pedal is fully depressed, there is not enough reserve pedal movement.

Note: This does not apply to power operated braking systems, providing the foot valve is fully open before the pedal is fully depressed.

6. A service brake control inappropriately repaired or modified.

3.3 Hydraulic systems including Servo Assisted

Information
Method of Inspection
B. Hydraulic systems including Servo Assisted

1. Fully depress the pedal twice, first slowly and then rapidly each time to a point where sustained pressure can be held. Check for creep and sponginess.

2. If a vacuum servo is fitted, then with the engine off, totally deplete the stored vacuum by repeatedly applying the service brake. Fully apply the brake and hold at a constant pressure. Note whether the pedal can be felt to travel further when the engine is started.
Reason for Rejection
1.
a. The pedal tends to creep down while held under pressure
b. sponginess indicating air in the hydraulic system.

2. No dip can be felt when the engine is started, indicating vacuum assistance is not working satisfactorily.

3.3 Vehicles with high servo boost

Information
This Inspection applies to all vehicles where pedal creep has been detected when pressurising the brakes with the engine running.
Method of Inspection
C. Vehicles with high servo boost

1. Where possible check the brake fluid level in the reservoir then pump the brake pedal several times and check that the fluid level in the reservoir is unchanged.

Note: Under no circumstances must the reservoir cap be removed.

2. With the vacuum depleted ensure the pedal is not spongy or does not creep.

3. With servo assistance fully depress the pedal.
Reason for Rejection
1. After several applications of the brake pedal the fluid level in the reservoir has decreased.

2. With the vacuum depleted the pedal is spongy or creeps.

3. With servo assistance the pedal creeps down and touches the floor.

3.3 Full power hydraulic braking systems

Information
Some vehicles with full power hydraulic braking Systems will illuminate the low pressure warning light as soon as the ignition is switched on. In these circumstances it is not a Reason for Rejection unless the warning light stays on after the engine has been started.
Method of Inspection
D. Full power hydraulic braking systems

1. Check that a warning device is fitted.

2. Check whether a warning device fitted is audible or visible to the driver.

3. With the engine switched off, repeatedly apply the service brake until the warning device operates. Check that at least two further applications of the brakes are available. In case of doubt the availability of two further applications can be established when testing the brakes on a Roller Brake Tester.
Reason for Rejection
1. No warning device fitted.

2.
a. A warning device not visible or audible to the driver
b. a visual warning device not readily visible to the driver in darkness.

3.
a. A warning device not working correctly
b. insufficient reserve pressure to give at least two further applications of the brakes after the warning device has operated.

3.3 Air and vacuum systems including over hydraulic

Information
This inspection applies to vehicles registered on or after 1 October 1937.

A vehicle that weighs 3050kg or less unladen, with a reservoir coupled direct to the induction manifold, or a reservoir integral in a servo unit, is not necessarily required to be fitted with a warning device.

A defective audible warning device is not a Reason for Rejection if fitted in addition to an operational visual device.

For vehicles first used on or after 1 April 1983, a defective visual warning device is not a reason for rejection if fitted in addition to an operational audible device.

If the pressure or vacuum gauge has no warning mark, the following reference values should be used when assessing whether there is still enough pressure or vacuum in the system:
45psi 3.1kg/sq cm or 3 bar for a pressure gauge
10 to 12 25 to 30cm for a vacuum gauge
Method of Inspection
E. Air and vacuum systems including over hydraulic

1. Check that a visual warning device or, as an alternative for vehicles first used on or after 1 April 1983, an audible warning device is:
a. fitted
b. working correctly.

2. Check that any visual warning device is:
a. visible from the driving seat
b. illuminated, or otherwise visible from the drivers seat in darkness.

3. For systems fitted with a pressure or vacuum gauge, with the reservoir at a maximum pressure or vacuum, note the reading on the gauge and then fully depress the pedal. Keep the pedal depressed and watch the gauge reading.

Note: All vehicles must also be checked for pressure or vacuum leaks during the undervehicle inspection of the brake system.

4. Check that the operation of any air or vacuumpowered system e.g. wipers etc. does not adversely affect the operation of the braking system.

5. By applying the service brake repeatedly, gradually empty the braking system, and
a. if a gauge is fitted, note that:
the reading on the gauge falls steadily each time the brake pedal is depressed, and
when the gauge needle has reached the warning mark, there is still enough pressure or vacuum in the system to allow the brake to be applied at least twice more with pressure or vacuum assistance
b. if a warning light or other device is fitted, check that, after the warning has operated there is still enough pressure or vacuum in the system to allow the brake to be applied at least twice more with pressure or vacuum assistance.

6. Completely empty the reservoir by repeatedly pressing the service brake pedal. Start the engine and if diesel run it at just below the governed speed or 2000 rpm if petrol. Note the time it takes for the warning device to stop operating.
Reason for Rejection
1. A mandatory warning device:
a. not fitted
b. not working correctly.

2. A visual warning device:
a. not visible from the drivers seat
b. not illuminated, or its function not visible from the drivers seat in darkness.

3. The gauge reading drops whilst the pedal is kept depressed, indicating a leak in the brake system.

4. The repeated operation of any ancillary air or vacuum system completely depletes the stored air or vacuum for the braking system.

5.
a. Insufficient pressure or vacuum to give assistance to brakes for at least two or more applications after the gauge has reached the warning mark
b. insufficient pressure or vacuum to give assistance to brakes for at least two or more applications after the warning light or other device has operated.

6. The time between starting the engine and the warning device ceasing to operate or the gauge showing a safe reading indicates that build-up of pressure/vacuum is too slow.
For example:
more than 3 minutes for pressure systems
1 minute for vacuum systems.



Reproduced from the MOT Inspection Manual by kind permission of THE VEHICLE INSPECTORATE.
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