STM Italy

Heart of STM Slipper Clutch

Primary Spring
• it makes pressure on the disk pack throught the pressure plate.
• it allows the transmission of engine torque to rear wheel.

Secondary spring
• it makes pressure on the drum.
• it allows the adjustment of the slipper clutch system and the engine brake.

Spring functioning
The primary and secondary springs are pre-loaded in order to generate an inertial elastic strength of contrast.

Primary spring functioning
When you operate clutchlever, the primary spring is compressed. The spring releases an elastic strength of contrast to the lever movement.

Secondary spring functioning
During braking, the torque coming from the rear wheel makes the drum rotate and shift outwards causing the discs to disengage. The secondary spring is compressed in comparison with the initial resting position and generates an elastic strength of contrast.