Brake pedal

The plate (4) pushed by the flexible blade (5) reacts on the toothed ring nut (3) and the catch (9) permanently in contact with the ring nut, prevents it from turning.

When the brake is released, the self-adjusting device is again compressed by the action of the upper shoe return spring (6): the toothed ring nut (3) stops in the angular position taken during braking.

This stop during rotation is due to the friction between the plate (4) and the toothed ring nut (3). With the toothed ring nut (3) locked during rotation, if the condition of wear of the lining due to previous braking actions is sufficient, the catch (9) engages the next tooth.

The maximum stroke of the toothed ring nut (3) on the adjustment screw (2) is one tooth (0.020 ÷ 0.025 mm): an exception to this is settling of the brakes after dis-assembly, in which case the stroke is two teeth.

If after prolonged braking, the brakes overheat and the temperature reaches 100° ÷ 110°C, the flexible blade (10) comes into action, which flexes and blocks the plate (4) in the neutral position.

During braking the toothed ring nut (3) will no longer be subjected to the thrust of the flexible blade (5), therefore the catch (9) will take the same angle as the ring nut tooth, which will be free to run with the adjustment screw (2) on the catch (9) without taking up the play caused by the expansion of the drum.

When overhauling, before assembly of the brake linings, the toothed ring nut (3) must be moved to contact the spring (7) and slackened one half of a turn.

BRAKE PEDAL

REMOVAL/REFITTING

• Remove the fuse box and its support bracket (see GROUP 55).

1. Turn and remove the stop light from its housing.
2. Remove the pin fastening the brake pedal to the servobrake.
3. Slacken the fastening nut and remove the brake pedal.