Actuator with:

Bi-directional Travel, Preset Seating Force at End-of-Travel, Variable End-of-Travel Position (+/- .100'), Obstruction Sense and Shutdown, Maximum Force Limit for Safety

The actuator incorporates spring loaded end bushings, B, on a .125" pitch screw, G. The screw is driven by a stepper motor through a belt and gear, A.

When the carriage, E, including nut, F, reaches the end-of-travel seating position, it stops. As the screw, G, is still turning, provision is made for the screw to translate in the opposite direction. Screw translation is allowed by spring-loaded bushings at each end. The preload in these springs both determines the seating force and provides a force limit for safety.

Translation of the screw is sensed by a bar, H, riding in a chamfered groove on the screw. Screw translation, in either direction, causes the bar, H, to move upward, actuating a microswitch, I. The screw drive gear, A, is driven by a flexible belt which accommodates axial motion of the gear.

End-of-travel in either direction is sensed by optical switches, C, being broken by flags, D. Microswitch, I, sensing screw translation simultaneously with either optical switch, C, being broken, indicates an acceptable end-of-travel event. If the microswitch, I, senses screw translation without either optical switch, C, being broken, the system assumes an unacceptable obstruction has occurred and shuts down hard, requiring manual intervention to bring the system back up.

Rod, J, is the lower carriage guide rail. Screw, G, through nut, F, functions as the upper carriage guide rail.