Patent GB-539584-A (GB)
Title: Improvements in or relating to starting and stopping mechanism of power driven machines
IPC: A43D27/00
Filed: 1940-03-14
Abstract: 539,584. Starting and stopping mechanism for machines. BRITISH UNITED SHOE MACHINERY CO., Ltd., HEATHER, C. H., and KEALL, F. B. March 14, 1940, Nos. 4767 and 14639. [Class 80 (ii)] [Also in Group XXXIV] In power driven machines, such as presses, in which a dog 24 co-operates with a lever 26 for actuating brake and clutch apparatus for starting and stopping the machine, the dog 24 instead of being pivoted to a purely reciprocating point 17 of the connecting rod 16, as hitherto, is pivoted to the connecting rod 16 on a pivot 29 offset from the pivot 17. Thus the brake actuated by the lever 26 will continue to operate even should the machine shaft 12 slightly overrun. Means for preventing actuation of the mechanism should the machine get out of adjustment are provided. In the revolution press shown, the lever 26 actuates a clutch and a band brake in a manner such as described in Specifications 4833/13, [Class 80 (ii)], and 498,469. In the position shown the dog 24 engages the lever 26 and is held against an abutment 38 on the vertically reciprocable cross-head 18 by a spring 36. The dog 24 has a trip plate 34 engaging a trip plate 30 on a bar 32. The latter at one end has a pin-and-slot connection with a link 40 pivoted to a link 50 articulated to the lever 26, and at the other end has a roller 56 slideble in a guideway 54 in a link 48 pivoted to a treadle 96. The left-hand end of the bar 32 is urged upwardly by a spring 58, but upward movement is prevented by an abutment 42 on the bar 32 engaging a pawl 46 pivoted to the link 48. The treadle 96 has a vertical arm 95 connected by a rod 97 passing through a slotted block 98 pivoted to the link 40. In operation the treadle 96 is depressed to move the rod 97 and hence the bar 32 to the left. The trip plate 30 through the trip plate 34 disengages the dog 24 from the lever 26 so that the latter is free to engage the clutch and release the brake mechanism. When the shaft 12 has rotated through one revolution the dog 24 re-engages the lever 26 and the clutch is disengaged and the brake engaged. Should the shaft 12 overrun beyond a pre-determined limit a cam 64 thereon trips the pawl 46 to allow the bar 32 to rise under the action of the spring 58, and so prevent engagement of the trip plates 30, 34. The machine cannot thus be re-started upon another depression of the treadle 96. The bar 32 is retained in its upward position by a catch 82, Fig. 2. Both hands of the operator are required to disengage it from the catch 82. A handle 84 on the pawl 46 permits of manual disengagement of the latter when desired to put the mechanism out of operation. The brake band 70 engaging a drum 72 on the shaft 12 has end portions 74, 76. bent inwardly around pins 78, 80 of the usual adjusting mechanism. The ends carry packing pieces 86, 88 to which the brake lining, 90 is also attached. The tendency of fracture of the rivets 94 is thus decreased. In a modification of the starting and stopping mechanism, the right hand end of the bar 32 is connected to a two part weighted lever having a curved face engaged by a link connected to the connecting rod. Should the machine overrun its limit the link rides off the curved face so that the weighted lever drops to lift the bar 32 and thus prevent engagement of the trip plates 30, 34. Specification 403,084 is referred to.