Patent GB-893933-A (GB)
Title: Improvements in or relating to brakes
IPC: F16D55/224
Filed: 1959-02-13
Abstract: 893,933. Disc brakes; fluid-pressure brake control systems. CANADIAN WESTING- HOUSE CO. Ltd. Feb. 13, 1959 [March 4, 1958], No. 5064/59. Class 103 (1). The brake levers of a hoist brake are actuated to apply the brake either by a fluid-operated device or by a weight member actuating a wedge member engaging the levers. A Koepe drum 10, 11, Figs, 2, 3, is provided with four brakes 12, each comprising frictionpads 21 pivoted to arms 18 pivoted at 19 to a frame 16, 17, 20 and forced apart for braking either by the double piston, compressed air cylinder 23 or by a weight 28 released by cylinder 33 to slide down guides 28A to force a wedge 29 between rollers 30 on the arms. The pistonrods 26 are adjustable to take-up wear. Enlarged parts 28C of guides 28A prevent rocking of the weight in the raised position and the wedge 29 and weight 28 are connected by rollers 29A in slots in the weight and/or wedge. In the brake control system, Figs. 4, 6, the parts enclosed by the broken line in Fig. 4 are supplied to each brake. Compressed air (80- 100 p.s.i.) is delivered via pipe 36 to regulating- valves 37, 38, 39 having outputs of 70, 30 and 5 p.s.i., respectively; a manually-operable valve 40 supplies air from pipe 36 via valves 44, 45, 46 to a relay valve 48 controlling air supply from pipe 36 to brake cylinder 23. Valves 44, 45, 46 and a valve 47 are actuated only on energization of a solenoid and a preset pressure existing at inlets D, and when actuated ports C and A are connected and when released ports B and A are connected. With no air in the system, the brakes are applied by the weights 28 and on charging compressed air is supplied to valves 37-40 and ports 44D, 47D, 48F. Manual control is obtained by movement of a manual/automatic selector switch to close contacts MAN1, MAN2, MAN3, move lever 41 to full-on, and press button 54, Fig. 6. Relay 50 is energized to close contacts 50A and energize solenoids of valves 44, 45, the valves 44 then supplying pressure from valve 40 to switches 53 to close contacts 53A and energize relays 52, close contacts 52B and energize relays 55 and solenoids of valves 46; contacts 52A are opened by relays 52 to maintain valves 47 released. Energization of relays 55 closes contacts 55C to maintain relays 55 energized independently of relays 52 and switch 53. Contacts 55B are - closed and contacts 47E, Fig. 4, maintained closed by valves 47, to energize relays T. Actuation of valves 44-46 supplies pressure to valves 48 to supply full pressure to cylinders 23 and ports 49D via the released valves 47. After a delay, in which volumes 56 and cylinders 23 are charged, the valves 49 are actuated, when pressure in cylinders 23 exceeds 60 p.s.i., and air from valves 37 is fed to cylinders 33 to raise weights 28 and close contacts 51A. On moving lever 41 to reduce pressure from valve 40, contacts 53A open, de-energizing relays 52 to close contacts 52A and open contacts 52B, to actuate valves 47 which now supply air from 49A to 49D to lock valves 49 in the actuated position to maintain cylinders 33 charged. The brakes are now under full manual control. If on braking, the full pressure is not supplied to cylinders 23, due to a fault, air will pass from reservoirs 56 via a leak 59 by-passing oneway valves 60 to cylinder 23 until the pressure at 49D drops sufficiently to release valves 49 and connect cylinders 33 to atmosphere via ports 49C, at a predetermined drop in pressure in cylinders 33 quick vent valves 61 are opened and as the weights descend contacts 51A are opened to release valves 44-46, the valves 46 connecting reservoirs 58 to inlet 48E to supply air to cylinders 23 for emergency braking; this air, however, leaks to atmosphere via leak 62 but provides an overlap of braking to permit the weights to be completely lowered. The non- faulty brakes will remain applied by brake cylinders 23 and means may be provided to indicate the faulty brake. Automatic braking.-The change to automatic braking can only be done with the cage at a level, due to an interlocking device, at which contacts MSX are open and since the cage is in a creep speed zone, the contacts CSR are open. In automatic control, contacts MAN1, MAN2, MAN3 are opened to release valves 44, 45, deenergize relays 55 to open contacts 54A and release valves 46, 47 which with the release of valves 44, 45 causes brake application with air from reservoir 56 or, on failing that, by the weights. If valve 47 of any brake fails to release, contacts 47E will not close and since contacts 55B are open the relay T opens contacts TA to de-energize the main relay 50 to apply the brakes as immediately above. A signal from starting of the hoist motor or from a programme control for determining the cage's acceleration or deceleration, closes contacts MSX to energize relays 55 to close contacts 55A and actuate valves 46. Switch 53 is released so contacts 52A are closed and valves 47 actuated. Air at 5 p.s.i. from valve 39 is supplied via valves 45, 46 to relay valves 48 which prime the cylinders (at 5 p.s.i.). Actuation of valves 47 supplies pressure from cylinders 33 to ports 49D to maintain valves 49 open. As the cage leaves the creep-speed zone, contacts CSR are closed to actuate valves 45 and connect relay valves 48 to atmospheric ports 44B to release the brakes through atmospheric ports 48H. When the cage enters a new creep speed zone, contacts CSR open to release valves 45 to re-apply the priming pressure to cylinders 23. At the new level contacts MSX opens to de-energize relays 55 to release valves 46, 47 and apply full-pressure from relay valves 48 to the brake cylinders 23. If pressure supply is lost during motion of the cage, the valve 47 is released since pipe 36 is connected to port 47D, valve 49 is released, due to no pressure in cylinder 23, and the weights descend to apply the brakes. The hoist motor is stopped by opening of any pair of contacts 51A or by switch if wear in pads 21 is excessive. In an alternative control system, Figs. 5 and 6, the valve 40 includes a switch 68 operated by handle 41 to close on braking to release valves 47 directly instead of through relay 52; a warning device 70 is operated when the piston of cylinders 23 moved beyond predetermined limits to indicate wear; and the outlet ports 49C are connected to the cylinders 23 and inlet ports 47C to pipe 36, the valves 49 being responsive to loss of pressure in pipe 36 to unlock and apply the weights as soon as low pressure is detected in cylinders 23. On release of valves 49 the cylinders 33 and 23 are connected so that as the weights descend air will be driven from cylinders 33 into cylinders 23 to maintain braking until the weights begin to take over the braking. Additional braking is obtained from valve 37 or a similar valve 71 (output at 90 p.s.i.); with valve 72 release air passes from valve 37 (60 p.s.i.) to valves 49 but when actuated by manual operation of button 73 or the cage engaging the limit switch 74 air passes from valve 71. Canadian Specification 584,034 is referred to.