STM Italy

Heart of STM Slipper Clutch

Primary Spring
• pressure action on the DISC PACK through the pressure plate.
• function of coil springs.

Secondary spring
• pressure action on the DRUM;
• it is used to adjust the opening of the clutch during the anti-skid, then to adjust the engine brake.

How springs work
The primary and secondary springs are mounted in such a way as to guarantee a preload which generates an initial resilient spring force.

How the primary spring works
When the lever is actuated, the preloading position of the primary spring is varied and reduced. The spring returns an elastic force of contrast to the action of the lever.

How the secondary spring works
The torque generated by the rear wheel tends to raise the drum. The secondary spring is compressed with respect to the initial resting position and generates an elastic contrast force.