GB643614A - Improvements in or relating to apparatus for effecting the movement of couches, tables or the like, relative to their supporting member or members - Google Patents

Abstract

643,614. Control of A.C. motors. GENERAL ELECTRIC CO., Ltd., and BRYER, R. F. May 4, 1948, No. 12253. [Class 38(iii)] An electric motor is adapted to tilt a couch or the like between extreme positions, means being provided to interrupt the movement of the motor-driven member when it attains a pre-determined position, such as the horizontal position, intermediate the limits of its movement, the movement being interrupted either for a short period or until the motor is re-started by an operator. As shown, the driving motor 1 is of the capacitator type having main auxiliary and brake windings 2, 3 and 4 respectively and a capacitator 5. When the couch is to be moved to the horizontal position, a threeposition foot-operated reversing switch, having contacts 6 and 7, is adjusted to afford the desired direction of rotation, the motor-circuit being completed through a rotary limit switch 8 which may be mounted with its axis coincident with the lateral axis of the couch. When the couch has reached the horizontal position, a switch 10 is broken by a motor-driven cam and the motor will stop since the current passing through a transformer primary winding 11 is insufficient to operate the motor. The switch 6-7 may then be opened, the couch being retained in the horizontal position. If the switch 6-7 is not moved, current is induced in the transformer secondary winding 13 and a thermal element 12 will eventually become sufficiently heated to make contact with terminal 14 and short-circuit the winding 11 so re-starting the motor. Movement of the motor-driven cam will reclose the switch 10 and the element 12 will cool and return to its normal position. The thermal switch may be replaced by other time-delay devices. In the modification of Fig. 2, the couch is returned to the horizontal position by appropriate movement of switch 6-7, a switch 21 occupying the position shown when the couch is not horizontal. A relay 15 is energized and closes self-maintaining contact 16. When the couch reaches the horizontal position, switch 21 is moved to its alternative position and a relay 18 is energized through contact 17. Contacts 19, 20, then interrupt the motor-supply. The motor is re-started by first moving the switch 6-7 to the " off " position and then returning it to an operative position. Clutch mechanism may be used for interrupting the movement of the couch when it reaches the horizontal position.