Abstract: A hand-held power tool for inhibiting uncalled-for rotation of the output shaft and for self-compensating for wear. The tool comprises a housing, a braking member fixedly mounted in the housing and an output shaft mounted in the housing for rotation. The output shaft has an outer end portion for reception of an attachment. A ratchet wheel on the output shaft is adapted to be driven in one direction or the other, has a side face facing a first surface of a wear member, and has a plurality of recesses extending inward from the side face. The wear member is keyed to the output shaft for conjoint rotation. A plurality of engagement members are received one in each recess and biased outward against the first surface to bias a second surface of the wear member against the braking member for holding the ratchet wheel against rotation opposite the driven direction.

Abstract: A hand-held power tool with improved means for inhibiting uncalled-for rotation of the output shaft that is relatively long-lived and self-compensating for wear. The tool comprises a housing, a braking member fixedly mounted in the housing and an output shaft mounted in the housing for rotation. The output shaft has an outer end portion projecting out from the housing for reception of an attachment for the tool. A ratchet wheel on the output shaft is adapted to be driven in one direction or the other. The ratchet wheel has a side face facing a first surface of a wear member (e.g., washer) and a plurality of recesses extending inward from the side face spaced at intervals. The wear member is keyed to the output shaft for conjoint rotation with the shaft.

Abstract: A hand-held power tool includes a housing having spaced front and back walls, and an output shaft mounted in the housing for rotation in one direction or the other on an axis extending transversely with respect to the walls. The shaft has an outer end portion projecting out from the front wall for reception of an attachment for the tool. A ratchet wheel on the shaft in the space between the walls is adapted to be driven in one direction or the other for rotating the shaft in the one direction or the other. The ratchet wheel has a side face facing a fixed surface on one of the walls and a plurality of recesses extending inward from the side face spaced at intervals around the axis. Cylindrical pins are each engaged by a corresponding one of a plurality of coil compression springs for biasing the pin outward from the recess against said fixed surface for holding the ratchet wheel against rotation in a direction opposite the driven direction of rotation.

Abstract: A camp-on detecting system for a private automatic branch exchange (PABX) is provided with the camp-on connecting function for connecting queuing or camp-on calls to a busy line circuit. On detecting that the control line of the line circuit is at a busy potential, the potentials on the control lines of all camping-on trunks are changed and the potential changes are detected by the detecting means connected to the line circuit to detect that a camp-on connection has already been made to the line circuit.