Spring wrap clutch with brake

Abstract

A clutch assembly which provides selective output drive especially adapted for use in incrementally driving a platen and tape reader mechanism for use in printers. An output gear is freewheelingly mounted upon the clutch assembly driven shaft and is mechanically linked to a free wheeling cam through a helical spring wound tightly about the driven shaft. The free wheeling cam is provided with at least one notch for selective engagement by a pivotally mounted solenoid actuated latch. When the latch is disengaged from the free wheeling cam, the spring is rotated by the driven shaft and imparts its rotation to both the output gear and the cam. Upon actuation of the solenoid, the latch member engages the free wheeling cam member to restrain it from rotation, causing the helical spring to unwrap itself (i.e., loosen) about the shaft and stop the output gear from rotating. The spring, however, attempts to rotate the output gear in the reverse direction, which action is prevented by backstop engaging a shoulder in the cam surface provided in the output gear. The clutch assembly is characterized by its simplicity of design and ease of manufacture and assembly.