The PSI series is the basic wrap spring clutch. Input rotation can be applied either through the free hub to the shaft assembly.

Like all wrap spring products, no adjustments or maintenance is required, only installation onto the desired shaft and to provide a means of mechanically stopping the control collar is required.

The control tang is fixed into the control collar and thereby the spring is either allowed to couple or to release the input from the output.

The PSI series is supplied in 3 configurations designated models “O”, “SS” and “S” to give the functions required to suit the specific application.

Model “O”, Overrunning - Uses include: one-way clutch, anti-backup or anti-over run devices.

Torque will be transmitted in only one direction while a minimum drag torque will result when rotated in the opposite sense.

Model “SS”, Start-Stop - Provides torque transmission to the load upon demand and decouples the load when the control collar is restrained.

The load can still be moved, if required, in the normal forward direction.

As with most wrap spring products the load cannot be moved in the opposite direction.

Model “S”, Single revolution - For stopping as well as starting the load thus allowing for single revolution applications where positional requirements exist.

Stopping position accuracies of ±4°, noncumulative, can be expected. The braking capacity is limited to 20 % of the clutch rated torque.