Patent ID: 8616341

Claim:
In a railroad handbrake including a housing, a force-producing chain extending from the housing and connectable at one end thereof to a brake rigging of a railcar, a chain application and release mechanism at least partially disposed within the housing and a holding pawl, the holding pawl having each of a body thereof mounted for rotation and a ratchet-engaging portion thereof extending from said body and cooperating with a ratchet wheel of the chain application and release mechanism, the railroad handbrake further including means for biasing the ratchet-engaging portion of the holding pawl for engagement with the ratchet wheel, a chain tension sensing device comprising: (a) an elongated bore formed through a thickness of the body of the holding pawl so that the holding pawl is mounted for a generally linear reciprocal movement in a direction being generally transverse to a rotational axis thereof; (b) a sensor target disposed on and attached to an exterior surface of the body of the holding pawl, said sensor target extending in a direction being generally opposite to a direction of the ratchet-engaging portion of the holding pawl, said sensor target being disposed for said generally linear reciprocal movement with the body; (c) a sensor mounted in close proximity to an upper end of the housing; (d) whereby the ratchet wheel moves the body of the holding pawl in a direction towards said sensor in response to tension at least partially attained on the force-producing chain during said at least partial handbrake application and positions said sensor target in operative sensing alignment with said sensor; and (e) whereby the biasing means moves the body of the holding pawl in an opposite direction towards the ratchet wheel during handbrake release causing said sensor target to move away from said operative sensing alignment with said sensor.