GB760106A - Improvements relating to pedal mechanisms for operating electric switches controlling an electrical machine - Google Patents

Abstract

760,106. Controllers; switches held set and freed mechanically. TAYLOR (BIRMINGHAM), Ltd. C. March 15, 1954 [Jan. 22, 1933], No. 1846/53. Classes 38(3) and 38(5) A controller for an electrically-driven machine tool comprises spring- biased pedals 9, 10, 11, adapted respectively for fast, slow, and reverse operation of a machine, a trip pedal 12 being provided, in addition, to stop the machine in an emergency. Depression of pedal 9 causes its abutment 29 to engage cam 26 so that a latching device rotates against the bias of a plunger 23 and the pedal is latched in a depressed position by means of a hook which engages the abutment 29. At the same time, a spring- biased plunger 14 depresses the actuating member of a switch 4 related to the pedal 9 and the driving motor is connected for fast operation of the machine. When the pedal 9 is thus held in the depressed position, actuation of the pedal 10 to its latching position releases the first pedal, this arrangement being reciprocal. To stop the machine, pedal 12 is depressed so that arms 13 engage a bar 22 of the latching device to tilt the latter and release any pedal which is engaged by its retaining hook. The plunger 17 for the particular pedal exerts an upward thrust and returns the pedal to its normal position. The reversing pedal 11 is not latched in the depressed position since reversal of the machine is not likely to be of long duration. When the pedal 11 is depressed, an abutment thereon engages a cam for tilting the latch device and releasing either of the previously latched pedals 9 or 10.