2008 Mercedes Benz Truck R 320 CDI (251.122) V6-3.0L DSL Turbo (642.950)
Parking Brake System: Service and Repair
AP42.20-P-4290-01BA Bed in parking brake according to instructions.
When the parking brake is operated the catch of the pedal or hand-lever must not lock in position
1 Driving on dry road, initial speed approx. 50 km/h
Operate the pedal or parking brake hand-lever 2 to 3 times with 100 to 200 N and brake the vehicle to a standstill.
Since the brake lamps do not light up, particular attention must be paid to following traffic!
2 Driving on dry road at a constant speed of approx 50 km/h.
Actuate the parking brake pedal or hand-lever with a force of max 100 N for 10 seconds.
3 Drive on the dynamometer or function test stand at a constant speed of 50 km/h (3rd gear).
Actuate the parking brake pedal or hand-lever with a force of 100 N for 10 seconds. The specified force must not be exceeded.
4 On the brake test stand operate the pedal or parking brake hand-lever for approx. 2 minutes with a constant force of 150 to 200 N.
Do not lock the parking brake pedal or hand-lever!
When bedding in the brakes, heat causes the brake disc bowl to expand, reducing the operating forces.
The bedding-in procedure can be repeated when the parking brake has cooled.
5 If the parking brake does not release satisfactorily after the test, or pulls to one side after bedding in the brakes and adjusting (maximum
permissible deviation from higher value: 50%), check brake shoes and brake cables and replace if necessary.
The German specifications specify a minimum retardation of 20% for the parking brake.
The retardation is the ratio of the sum of the braking forces at the wheels to the gross weight.
A maximum deviation of 50% from the higher value is permissible.
The regulations for other countries should be observed in each case.
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Parking Brake System: Service and Repair
AP42.20-P-4290-01BA Bed in parking brake according to instructions.
When the parking brake is operated the catch of the pedal or hand-lever must not lock in position
1 Driving on dry road, initial speed approx. 50 km/h
Operate the pedal or parking brake hand-lever 2 to 3 times with 100 to 200 N and brake the vehicle to a standstill.
Since the brake lamps do not light up, particular attention must be paid to following traffic!
2 Driving on dry road at a constant speed of approx 50 km/h.
Actuate the parking brake pedal or hand-lever with a force of max 100 N for 10 seconds.
3 Drive on the dynamometer or function test stand at a constant speed of 50 km/h (3rd gear).
Actuate the parking brake pedal or hand-lever with a force of 100 N for 10 seconds. The specified force must not be exceeded.
4 On the brake test stand operate the pedal or parking brake hand-lever for approx. 2 minutes with a constant force of 150 to 200 N.
Do not lock the parking brake pedal or hand-lever!
When bedding in the brakes, heat causes the brake disc bowl to expand, reducing the operating forces.
The bedding-in procedure can be repeated when the parking brake has cooled.
5 If the parking brake does not release satisfactorily after the test, or pulls to one side after bedding in the brakes and adjusting (maximum
permissible deviation from higher value: 50%), check brake shoes and brake cables and replace if necessary.
The German specifications specify a minimum retardation of 20% for the parking brake.
The retardation is the ratio of the sum of the braking forces at the wheels to the gross weight.
A maximum deviation of 50% from the higher value is permissible.
The regulations for other countries should be observed in each case.
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