GB377317A - Improvements in or relating to vehicle brakes - Google Patents

Abstract

377,317. Fluid-pressure brakes. CADNEY, W., No. 1 Stores Depot, Royal Air Force, Kidbrooke, London. April 29, 1931, No. 12623. [Class 103 (i).] Relates to vacuum braking-apparatus for motor road-vehicles of the kind in which, for applying the brakes, one end of a cylinder is connectible to the induction-pipe of the engine, or, for releasing the brakes and for lubricating purposes, to the engine crank-case. According to the invention the communications are controlled by a single-piston or like valve operable by a foot-pedal or equivalent member, which is adapted to apply mechanical braking simultaneously with the vacuum braking or when the engine is not running. In the case of a tractor and trailer vehicle the cylinder may be arranged on the trailer for braking the latter, and the control valve and mechanical brake on the tractor. In the arrangement shown in Fig. 9, a piston-valve 18 slidable in a casing 8 places a port 7 leading to the brake cylinder 1, Fig. 3, in communication either via a lateral port 10 with the induction pipe, or via an end-port 13 with the crank-case. The upper end of the piston rod 17 passes loosely through a bracket 192 on the brake pedal 19, while a spring 191 is disposed between the bracket and a shoulder on the piston-rod. In the normal position of the pedal 19 the brake cylinder is in communication with the crank-case ; when the pedal is depressed to the full line position, Fig. 9, the spring 191 moves the piston 18 to its extreme extent and the brake cylinder and induction pipe communicate, whilst on further depression of the pedal to the dotted position, the rod 17 slides through the bracket 192 and the mechanical brakes are applied to the single vehicle or tractor, as the case may be. Application of brakes from the piston 25 of the brake cylinder is effected by chain 24, lever 26, and rod 29 against the effort of a return spring 30. The opposite end of the cylinder 1 is fitted with a mushroom valve 31 having a loading spring 32 and designed to vent the cylinder when the braking effort exceeds a predetermined value. The braking arrangement may be combined with that described in Specification 369,702, the vertical operating push-rod referred to therein being connected through a bell-crank lever 43 and rod 42 to the brake rod 29, and a pin-and-slot connection 27, 28 between the lever 26 and rod 29 permitting independent operation by the two mechanisms.