GB695634A - Improvements in and relating to single operation clutches - Google Patents

Abstract

695,634. Operating positive clutches. WELWYN ENGINEERING CO., Ltd. March 21, 1951 (May 2, 1950], No. 10770/50. Class 80 (ii). Relates to a positive clutch 14, 16 of the kind which is automatically disengaged by one or more stationary cam-blocks 19 after performing a single operation of one or more or less revolutions in a machine-tool or the like, the camblock 19 being retracted against a spring 20 for clutch engagement by a connecting part 25 which is actuated by a link 23a to the starting- pedal and is automatically freed from the camblock 19 by a trip member 13a rotating with a driven part 13 of the clutch, so that release and further actuation of the starting pedal is obligatory before another operation can be started. In such a clutch the trip member 13a frees the connecting part 25 from the cam-block 19 through a pivotal member 24a with which the connecting part 25 is constrained to move in the freeing direction, as by a headed bolt 23c radially slidable in a groove in the pivotal member or by forming the connecting and pivotal parts 25, 24a integral, Figs. 6 to 8 (not shown). Means is also provided for preventing a further operation before completion of an operation. The clutch comprises a series of recesses 16 in a continuously rotating input worm-wheel 11, free on an output shaft 12 on which is fast a companion clutch-block 13 in which a slidable clutch-pin 14 is biased axially towards engagement with the recess 16 by a spring 15. To start an operation, the operator depresses a pedal (not shown) pulling downwards, through the link 23a, the connecting part 25 to retract the cam-block 19 which releases the clutch-pin 14 for engagement in the recess 16. The output clutch-block 13 is thus rotated, whereupon, after about 90 degrees rotation, the trip-member 13a on its rear face rides up a ramp 24e on the pivoted member 24a. which latter is thus urged rightwards and, through the bolt 23c, takes with it the connecting part 25 thus breaking the connexion between the latter and the cam-block 19. In the meantime the cam-block 19, now cleared by the lateral pin 17 of the clutch-pin 14, is spring-returned back to its starting position, shown, so that when, during further rotation, the trip member 13a releases the pivoted member 24a for leftward return by a spring 24f, the leftward return of the connecting part 25 is obstructed by the cam block 19 so that the camblock cannot again be pulled down to start another operation except by the operator releasing and again depressing the pedal. To render such pedal action ineffective during an actual operation, the output clutch-block 13 has a flange 13b with a gap 13c waich permits leftward return of the connecting part 25 only in the starting position shown. At the end of the revolution the clutch-pin 14 is disengaged by its lateral pin 17 riding up a helical cam-groove 21 in the arcuate upper face of the cam block 19, such groove having a blind end to act as a positive stop. Figs. 9 and 10 (not shown), provide for multiple revolutions by means of a counter on a parallel shaft and driven by a pin on the clutch-block 13 to operate a pivoted trip for the cam block 19. In Figs. 6-8 (not shown), the .operating pedal acts downwardly on the camblock 19 through a member pivoted for lateral movement above the shaft and taking the place of both members 24a and 25. This member is laterally tripped by the projecting rear end of the clutch pin 14.