Abstract: A multi-speed, direct current motor (120) incorporates a high speed (24) brush disposed between the low speed (22) and the common ground (26) brushes and having a non-arcuate end face (25) which, unlike the conventional arcuate brush end face (23,27), is not subject to speed-drift erosion. The non-arcuate end face (25) is configured of two offset surfaces (55,65 & 57,67) which intersect to provide a line of contact (43) between the end face (25) of the high speed brush (24) and the commutator (40) which is displaced from the center line of the high speed brush (24) in a direction counter to the direction of rotation of the motor, that is toward the leading edge (21) of the brush (24). The intersecting surfaces (55,65 & 57,67) may comprise either flat planar surfaces or contoured surfaces.

Abstract: A multi-speed, direct current motor (120) incorporates a high speed (24) brush disposed between the low speed (22) and the common ground (26) brushes and having a non-arcuate end face (25) which, unlike the conventional arcuate brush end face (23,27), is not subject to speed-drift erosion. The non-arcuate end face (25) is configured of two offset surfaces (55,65 & 57,67) which intersect to provide a line of contact (43) between the end face (25) of the high speed brush (24) and the commutator (40) which is displaced from the center line of the high speed brush (24) in a direction counter to the direction of rotation of the motor, that is toward the leading edge (21) of the brush (24). The intersecting surfaces (55,65 & 57,67) may comprise either flat planar surfaces or contoured surfaces.

Abstract: In an ISDN communications system, a remote station power detector circuit comprises a capacitor connected between center taps of transformers on the receive and transmit pairs of conductors. The capacitor stores energy delivered from a central DC power source. Two serially-connected opto-couplers form a discharge path for the capacitor. The first opto-coupler is periodically driven on to partially complete the discharge path. If the capacitor charge exceeds a predetermined minimum, the second opto-coupler will then be driven on, providing a logic level output usable by the remote station. Power consumption is minimized by the use of large resistors in series with the capacitor while reliable power detection is achieved by detecting accumulated charge on the capacitor. Dielectric isolation is provided through the use of opto-coupler circuits.

Abstract: An electric door lock actuator and door lock and latch mechanism are disclosed having manual and electric driven locking means. A combination of a lost motion coupling and resilient spring means for driving the motive means to a neutral position are utilized to effectively isolate the electric motor and gearing from the locking means such that the locking means may be operated manually without back-driving the electric motor and intermediate gearing. A specific rack defining a portion of the lost motion coupling together with a pair of springs mounted to engage a shoulder extending from a rack are disclosed to achieve the above function.

Abstract: A multi-link intercom with a sequencing logic circuit for controlling a solid state switching matrix to connect station through an available link. Control information from the stations is decoded and stored in a register under sequence control for completion of a connection from a calling station to a called available station over an idle link.