GB845709A - Improvements relating to thrust apparatus, and fluid pressure-operated brakes incorporating such apparatus - Google Patents

Abstract

845,709. Disc brakes; vehicle wheels. LAMBERT BRAKE CORPORATION. Dec. 6, 1956 [Dec. 8, 1955], No. 37371/56. Classes 103 (1) and 144 (1). In a fluid-pressure-operated piston - and - cylinder apparatus, particularly for brakes, a screw is threadedly engaged in a bore associated with the cylinder and is provided with a lost-motion connection to the piston such that the connection permits axial thrust to be imparted to the screw upon outwards movement of the piston to effect rotation of the screw to adjust its axial position but prevents counter-rotation of the screw under axial thrust imparted thereto through the connection following inwards movement of the piston through the distance corresponding to the lost-motion in the connection. In the wheel and brake assembly illustrated, a vehicle wheel 18 is mounted upon bearings 17 which are carried by the brake itself and the brake is centred on a stub-shaft 3 and is secured to the landing strut 1 of an aircraft by means of a number of pins 4 and studs 5. The brake consists of stationary annular plates 7 and 6 between which are housed fixed and rotating brake discs 26 and 25, respectively. When fluid under pressure is supplied to fluid-operated thrust-devices 34 housed in annular plate 7, the respective pistons 35 are moved outwardly to move actuator disc 27 axially towards backing-plate 12 secured to annular plate 6 against the action of brakerelease springs 31. Upon frictional engagement of the interleaved friction discs, a drag torque on the disc 25 adjacent actuation disc 27 will cause balls 30 working in inclined ramps to cam the actuator disc 27 and engage the brake with a self-energizing action. Wear of the friction surfaces is compensated for so that a constant release clearance is maintained as the respective adjuster screw 43 in each thrust device 34 is caused to shift axially along with piston 35 a distance equal to the wear to be compensated for, but are prevented from retrograde movement by virtue of resistance to opposite rotation of the screw as caused by the frictional engagement of the screw-head 46 with the end wall 47 of the piston 35. Heat generated during braking is prevented from passing to the fluid in thrust devices by a layer of insulating material of low thermal conductivity as at 53. The brake is cooled by air passing through openings 54 and 55 in the hub 9 of the stationary assembly and the backing-plate 12 is provided at its central opening 57 therethrough for the ingress of air into hub 9. Specification 665,854 is referred to.