GB587647A - Improvements relating to electromagnetically operated jack-type actuators - Google Patents

Abstract

587,647. Screw-and-nut gearing ; controlling change - speed gearing. ROTAX, Ltd., and MILLNS, T. W. Dec. 18, 1944, No. 25398. [Classes 80 (ii) and 80 (iii)] [Also in Groups XXVI and XXX] In a jack-type actuator for controlling changespeed gearing &c. motor b transmits motion through pinion k and idle pinion m, to toothed wheel q which is formed integral with a screwthreaded rotary spindle s. The latter transmits motion to the slidable crutch c by means of a nut comprising a cage 8 having balls 7 engaging the thread of the spindle s. Idle pinion m is supported by pivoted link n so that under the influence of spring 6 it is normally out of engagement but may be brought into action by the effect of plunger y, moving into recess 2 in pinion m upon the excitation of electromagnet 3. Toothed wheel c may be formed upon drum r within which is coiled spring t, connected at one end to the drum and at the other to stationary shaft u. Motor brake d may consist of spring- loaded member i bearing against disc f carried on armature spindle g and released by energizing electromagnet e. Limit switch 10 may interrupt circuit of motor b when the crutch c reaches a limiting position. Fig. 3 indicates the electrical circuit b' and b<2> being the windings of the motor armature and field respectively. At rest, armature of motor b is held by brake d. Upon supplying current to motor, brake d is released and electromagnet 3 is energized to cause plunger y to be inserted in recess 2 so that idle pinion m is aligned to transmit power from motor so as to move crutch c till switch 10 is actuated to stop the motor and release brake d. Electromagnet 3 remains excited to maintain extended position of the crutch. To retract the latter, electromagnet 3 is de-energised so that idle pinion m moves out of alignment and the crutch is free to be returned under the influence of spring t previously loaded upon extension.