The basic design of SP series clutches comprises a PSI unit assembled to a mounting plate with a solenoid actuator and an overtravel stop. It represents an autonomous clutch system to be con- trolled with a simple voltage pulse. Standard solenoids are 24 VDC and 12 VDC, 230 VAC solenoids are available on request.

SP-Series, single- or part revolution clutch/ brake units, employ a model “S” wrap spring. Model “SS” springs (no braking feature) are optional. This design offers a very economical clutch with a braking capacity of 20 % of the torque rating and a positioning accuracy of ±4°. The units are shaft mounted and they are available with hub- (HI) or shaft input (SI), clockwise (CW) or counter-clockwise (CCW), rotation always viewed from the free hub side.