Electric overload clutch

Claim 1

An overload protection clutch comprising: first and second rotational torque transmitting members axially aligned relative to each other; said torque transmitting members mutually engageable to transmit torque; said first torque transmitting member biased towards a first axial position by resilient means; normally energized electromagnetic coil means arranged in close proximity to said first torque transmitting member to attract said first torque transmitting member to a second axial position; magnet body means adapted to receive and retain said electromagnetic coil means; one of said first and second axial position constituting the fully engaged position and the other of said first and second positions constituting the fully disengaged position; said electromagnetic coil means and said resilient means arranged to provide a predominantly spring force in one of said axial positions and a predominantly electromagnetic force in the other of said positions, said forces being mutually opposed; disengagement triggering means operative upon overload to move said first torque transmitting member from the engaged position toward the disengaged position such that the force relationship of the spring and electromagnetic forces reverses and the dominating force completes the disengagement; and said disengagement triggering means consist of projections on the contact surface of one of said torque transmitting members and corresponding recesses on the contact surface of the second of said torque transmitting members.