GB588327A - Improvements relating to deceleration control apparatus for vehicles - Google Patents

Abstract

588,327. Brakes. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. (Westinghouse Air Brake Co,). Feb. 9, 1945, No. 3313. [Class 103(i)] Deceleration control apparatus for a vehicle comprises a rotary inertia device directly mounted on the vehicle axle housing and coupled through flexible transmission to control mechanism carried on a sprung part of the vehicle, the inertia device consisting of a flywheel driven by the axle in such manner that a predetermined amount of lead, relatively to the vehicle wheel, is permitted before any control is transmitted to the control mechanism. As shown, a straight-air system comprising a main reservoir 5, brake-pipe 2, self-lapping brake valve 3 and, in respect of each two-axled truck, a vent-valve mechanism 7 and brake cylinder 4, is provided with a rotary inertia device 14 on each axle. The vent valve 7 has a brake pipe connection 8 and a brake cylinder connection 9 and comprises a vent port 16, Fig. 4. controlled by a piston valve 17 having a large upper part 18 slidable in a cylinder 20 and a smaller part 19 slidable in a cylinder 21. The pipe 13 is vented, as described below, by the operation of the inertia device, causing a reduction in pressure in the chamber 27, so that the brake-pipe pressure under the piston part 18 raises the piston against the action of the spring 28. This positions the piston 19 above the ports 24 and connects the brake cylinder to atmosphere. In its upper position, the piston 19 contacts with a valve stem 33 and unseats the valve 30, thus connecting the chamber 27 with the chamber 34 beneath a diaphragm 38 carrying a valve 31. The springs 36,37 are so chosen that the brake cylinder pressure keeps the valve 31 open, so that the pressure in the chamber 27 reduces in accordance with the brake cylinder pressure. When this. pressure reaches say 18 pounds per square inch, the spring 36 closes the valve 31 and the pressure in the chamber 27 builds up, through the orifice 25, until the spring 28 restores the piston 19 to its seat 29. The time interval between the closing of the valve 31 and the closing of the valve 19, 29 permits further venting of the brake cylinder to say 8 pounds per square inch. The brake cylinder is then connected to the pipe 8 through the ports 24 and chamber 23 and is re-charged from the brake pipe 2. The reestablished brake cylinder pressure lifts the valve 31 and assists in maintaining the valve 30 closed, The inertia devices each comprise a flywheel 49 journalled by balls 57 on a shaft 48 which is driven from the axle 52 by a flexible connection 51. The driving-connection between the flywheel and the shaft 48 comprises a leaf spring 63, the free end of which is bent inwardly, contacting two spaced rollers 64 rotatable on a short shaft 65 fixed to the shaft 48. Deceleration of the axle will cause one of the rollers 64 to ride on the bent end of the spring 63, and bend the spring outwardly. The extent of relative movement between the rollers and the flywheel is limited by stops 61 which engage the rollers, the maximum angle of displacement being about 180‹. Deceleration of ten miles an hour per second, or more, bends out the spring 63 sufficiently to open the valve 69 against the action of the spring 71. The interior of the valve piston 66 is thus vented at a rapid rate through ports 79, 77, 78 and the pressure in the chamber 73, which is connected by the pipes 15, 13 and orifice 25 to the brake pipe 8, 2 and cylinder pipe 9, moves the piston 66 against the action of the spring 67, and opens the valve 68. The chamber 76 is connected to atmosphere, so that the chamber 73, pipes 15, 13 and chamber 27 of the vent valve 7 are vented rapidly. The brake cylinder is thus vented to allow the wheels to return to vehicle speed, and the spring 63 retracts to allow the valve 69 to close. The piston 66 re-seats and the pressures on the two sides thereof are equalized by the orifice 74. In a modification, the spring 63 when sufficiently flexed, pushes on a sliding spring-returned plunger carrying a contact ring which engages brushes to complete a circuit through a relay which establishes a circuit through a solenoid 83, Fig. 6. A plunger 82, carried by a lever 84 pivoted at 85, is thus drawn upwardly and opens the valve 86 to vent the pipe 13. The pressure on the valve 86, tending to close the valve, is balanced by the pressure on the diaphragm 105. In a further modification, the lever 84 is operated by a Bowden wire connection with the inertia device, the spring 63 pressing on one end of the wire. Alternatively, the casing housing the lever 84, valve 86 and diphragm 105 is secured to the casing of the inertia device, and the spring 63 bears directly on a plunger which actuates the lever 84.