Patent GB-1445105-A (GB)
Title: Multi-plate disc brakers for vehicles
IPC: F16D55/40
Filed: 1972-10-12
Abstract: 1445105 Multi disc brakes; cooling; friction clutches; clutch-brake combination; pistoncylinder actuators; hydraulic systems GIRLING Ltd 24 Sept 1973 [12 Oct 1972] 47006/72 Headings F2E F2F F2C and F2L [Also in Division F1] A railway vehicle disc brake with friction plate members 4, 7 mounted in a common housing 1 has pump means located within the housing 1 for circulating liquid through the housing 1, when the brake is applied, to cool the friction members 4, 7. In the embodiment of Fig. 1 the housing 1 is stationary and has projecting therethrough a rotatable axle 3 on which is splined a sleeve 2. A clutch arrangement 19-30 is selectively operable to connect sleeve 2 to a sleeve 8 on which are mounted members 7 for rotation therewith and axial movement relative thereto. The clutch comprises clutch plates 21 splined on sleeve 2 and plates 22 splined on a hub member 23. Angularly spaced balls 25 are located between projections 19, 24 on the sleeve 8 and the hub member 23, which projections are urged apart by a spring 27. With the brake inoperative the plates 21, 22 are held out of engagement by three pistons 28 acting on the hub member 23 through rods 30. The members 4 are non-rotatably mounted on torque pins 6 for axial movement relative thereto. A floating annular ring 9 actuatable as a centrifugal pump impeller surrounds the sleeve 8 and has passageways 10 therethrough. Passages (11) (Fig. 2, not shown) are also formed between friction pads 5 secured to members 4. The members 4, 7, 9 are adapted to be clamped together by operation of a piston 13. The piston 13 comprises thrust limbs 16, 17 connected by a bridge piece 18 which is resiliently deflectable. The members 4 and 7 and the impeller 9 each comprise inner and outer portions 4A, 4B; 7A, 7B; and 9A, 9B respectively which are splined or otherwise coupled together for relative movement to compensate for thermal distortion. Due to the resiliently deflectable bridge piece 18, equal loads can be applied to the portions by thrust limbs 16, 17 irrespective of thermal distortion. The housing 1 is filled with oil-emulsion coolant from a reservoir through an inlet connection 33, and the housing 1 has an outlet port 34 opposite the impeller 9. When the brake is applied, hydraulic fluid to pistons 28 is initially cut off to apply the clutch 19-30. The spring 27 urges hub member 23 axially to engage plates 21, 22-this causes the hub member 23 to rotate with the sleeve 2 and the balls 25 to ride out of recesses 26 to lock the hub member 23 with the sleeve 8 and members 7 which then rotate with sleeve 2 and shaft 3. Hydraulic fluid is then applied to piston 13 which clamps together members 4, 7, 9; the impeller 9 is driven with members 7 to induce liquid flow radially outwards through passage 10 and inwards through the passages (11). An orifice or valve is incorporated within the hydraulic lines 35, 36 to pistons 28, 13 to ensure that the piston 13 cannot be operated until pressure has first been released from pistons 28. In a further embodiment the clutch may comprise the interengagement between inclined faces on projections 19, 24. In a modified construction (not shown) the brake applying force is applied to the outermost members 4 by means of opposed pistons working in hydraulic cylinders in the end walls of the housing 1-and in such a construction the impeller 9 may comprise a one piece member. In a further embodiment a pair of centrifuga pump members are disposed between pairs or sets of stationary and rotatable members in which each set of members are clamped by a pair of opposed pistons, the inner piston comprising one of a pair of oppositely acting pistons in a common bore As shown, the clutch is immersed in the coolant but in a modification, seals 31, 32 can be repositioned so that the clutch is isolated, and not so immersed. In the embodiment of Fig. 3 the housing 1 is the wheel of a rail vehicle and is rotatable about a member 40; plates 4 are rotatable with housing 1 and plates 7 are held against rotation by a hub 41. A pair of annular floating clamp members 42, 43 are actuatable on the plates 7 through annular thrust rings 44, 45 comprising inner and outer limbs 48, 49 connected by bridge pieces 50 which are resiliently deflectable for load equalization. An annular piston 51 has a wedge shaped clamp face 54 for engagement with a face 55 on clamp member 42 and a reaction member 56 similarly engages clamp member 43. When hydraulic fluid is supplied to advance piston 51 the clamp members 42, 43 are advanced towards each other to clamp the plates 4, 7 together. The plates 4 act as impellers and a liquid flow is induced outwardly between plates 4, 7 and inwardly through passages in the clamp members 42, 43.