Start Position  Pre-Set Running Clearance

In the start position the toe of the rack touches the top of the cut-out. On the forward stroke the ASA rotates. The rotation of the ASA means the toe of the rack changes position and now touches the bottom of the cut-out.

Excess Clearance Phase

If there is Excess Clearance or wear, the stroke will be longer and the ASA will rotate further. The rack will remain touching the bottom of the cut-out throughout the forward stroke, therefore rotating the pinion in the slip direction of the one-way clutch assembly.

Elasticity Phase

When the brake linings touch the brake drum the ASA continues to rotate due to Elasticity in the brake. The increasing camshaft torque acts through the worm wheel and worm shaft, the coil spring is compressed and the conical clutch disengages.

Elasticity Phase

On the return stroke the ASA starts to rotate in the opposite direction. The rack is held down, keeping the same position in the cut-out, and rotates the one way clutch assembly, still disengaged from the worm shaft, in the opposite direction.

Pre-Set Running Clearance Phase

The rack moves with the housing during this phase, therefore the rack does not rotate the pinion. As the ASA rotates through the return stroke, the toe of the rack will move from the bottom to the top of the cut-out.

Adjustment Phase

The ASA continues to rotate through the return stroke. Held by the cut-out, the rack drives the one-way clutch assembly. The conical clutch is engaged, so the worm shaft rotates and indexes the worm wheel within the housing.