GB1232814A - - Google Patents

Abstract

1,232,814. Clutch/brake combination control; machinery safety devices. C. C. BROWN. 17 March, 1969 [16 March, 1968], No. 12864/68. Headings F2L and F2J. In an eccentric power press the eccentric 4 is driven through gear-wheels 3 and 5 from a shaft 1, the shaft 1 being clutched at 2 to a flywheel driven by an electric motor and, by axially moving the shaft, being braked by discs 7, 8, the clutch and brake being controlled so that engagement/disengagement of the clutch automatically releases/applies the brake, respectively. As shown in Fig. 2, the clutch is held disengaged by springs 14 acting on a rod 13 passing through the shaft 1. This disengaging force moves the shaft 1 and a brake disc 7 rigidly mounted thereon to the left, e.g. by 0À005 inch, to engage a fixed brake disc 8 and hence apply the brake. When fluid, hydraulic or pneumatic, is applied to the left-hand end of a piston 12, the rod 13 is moved to the right to engage the clutch and release the brake. A disc 15, Fig. 3A, rotates with the eccentric and is interconnected with a ram guard 23 for safety. The guard 23 is mounted on a lever 18 and, on lowering the guard manually, a roller 20 on the lever moves out of a slot 16 on the disc 15 and a gate 28 on the lever contacts a latch 25a on a link 25 to move the link down to open a valve 27 which causes a plunger (29), Fig. 3B (not shown), to extend out above lever 18 to prevent raising of the guard, and also permits fluid to flow to cylinder 10 to engage the clutch. The eccentric, and disc 15, then rotate through one revolution and a peg 17 on the disc strikes a plate 30 on the link 25 freeing the latch 25a and allowing the link 25 to move back up to close valve 27 which withdraws plunger (29) and releases the clutch. The guard is then raised by a spring 21. The spring and plunger may be replaced by a double-acting pneumatic piston and cylinder acting on the lever 18. An air cylinder 32 may be provided and supplied continuously with air to provide fail safe characteristics. It raises the link 25 should the return spring of valve 27 fail, and it moves latch 25a out of the path of the gate 28 should the air supply fail, so preventing the falling gate from closing valve 27.