Start Position  Pre-Set Running Clearance

In the start position the cut-out slot in the regulator is open. On the forward stroke the S-ABA rotates. The rotation of the S-ABA closes the cut-out as the regulator pinion rotates but the regulator worm shaft is held by the engaged conical clutch.

Excess Clearance Phase

If there is excess clearance or wear, the stroke will be longer and the S-ABA will rotate further. With the slot now closed, the one-way clutch in the regulator rotates in the slip direction. As the conical clutch is engaged the regulator worm shaft and clutch worm wheel do not rotate.

Elasticity Phase

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

Elasticity Phase

On the return stroke the S-ABA starts to rotate in the opposite direction. The conical clutch is still disengaged from the worm shaft so the regulator worm shaft and clutch worm wheel rotate freely. As the brake linings move away from the brake drum the camshaft torque drops, the coil spring de-compresses and the conical clutch re-engages.

Pre-Set Running Clearance Phase

The S-ABA continues to rotate. The regulator worm shaft is held by the re-engaged conical clutch but the regulator pinion rotates, opening the slot

Adjustment Phase

The S-ABA continues to rotate through the return stroke. The one-way clutch assembly is now rotating in the non-slip direction and drives the regulator worm shaft, rotating the clutch worm wheel. As the conical clutch is engaged the main worm shaft rotates and indexes the main worm wheel within the housing.