Patent GB-751772-A (GB)
Title: Improvements relating to hydraulic pressure operable vehicle brakes
IPC: B64C25/46
Filed: 1954-02-01
Abstract: 751,772. Hydraulic brakes. WESTING- HOUSE AIR BRAKE CO. Feb. 1, 1954 [March 31, 1953], No. 2894/54. Class 103 (1). In a hydraulic brake apparatus embodying automatic means for controlling the brake application when slipping of a vehicle wheel occurs so as to prevent the wheel from becoming locked and sliding, a manually operable master brake cylinder is connected to one or more brake actuators through an automatic means which allows the transfer of hydraulic fluid under pressure from the brake actuator or actuators to a hydraulic displacement chamber during slipping of the braked wheels, the hydraulic connection being opened and the hydraulic fluid being returned to the brake actuator or actuators when the slipping ceases. In the embodiment shown applied to an aircraft employing hydraulic apparatus for braking the wheel 1, a piston valve 5 is interposed between pipes 11 and 11a which connect the brake cylinder 2 and the master brake cylinder 3 for controlling communication therebetween. A reservoir 6 containing pneumatic fluid under pressure connects, through a release valve 7 controlled by a wheel slip responsive inertia-type control 8, the pneumatic pressure chamber 30 of the piston valve 5. If the wheel 1 is accelerating to ground speed immediately following touchdown or when the wheel is decelerating as a result of slip on the runway, the inertia mass within the inertia-type control 8 will either lag behind or overrun the wheel and operate the shaft 65, so as to move the release valve 7 to its release position. Assuming the latter set of circumstances where the aircraft wheel encounters an uneven or slippery condition on the runway such that the traction is insufficient to keep the wheel rolling against the retarding action of the brakes, the wheel then begins to slip and declerate. The inertia control device 8 then moves the shaft 65 and the rocker arm 63 in a counter-clockwise direction and rocks member 54 about pin 58 in a clockwise direction against the opposing force of the spring 59, thereby severing communication 51 from the reservoir 6 and establishing communication 52 to atmosphere. Pneumatic fluid pressure in chamber 30 is then released causing the piston 29 of the piston valve 5 to sever communication between the brake cylinder 2 and the master brake cylinder 3, via recess 36 in piston stem or valve 35, and to enlarge chamber 32 to receive hydraulic fluid from pipe 11 and chamber 10 in the biake cylinder 2 via passageway 33, whereupon the spring 16 will move piston 9 and piston rod 15 (controlling the brakes of wheel 1 by suitable means (not shown) back towards their normal position and release the brakes on wheel 1. The brakes having been released upon the occurrence of wheel slip, the wheel will accelerate to the ground speed of the aircraft. The inertia control device 8 then effects operation of the release valve 7 and thereby of the piston valve 5 to displace hydraulic fluid from chamber 32 into pressure chamber 10 of the brake cylinder 2, to re-apply the brakes on the landing wheel 1. If the wheel 1 again starts to slip before the aircraft comes to rest, the brakes will-again be released and, upon cessation of wheel slip, be reapplied in the manner above described until eventually the aircraft comes to rest. Specification 674,506 is referred to.