Patent GB-274043-A (GB)
Title: Improvement in brake actuating mechanism for automotive vehicles
IPC: B60T13/24
Filed: 1927-05-13
Abstract: 274,043. Bragg, C. S., and Kliesrath, V. W July 10, 1926 Fluid-pressure; force-transmitting mechanism. -A fluid pressure brake for automobiles comprises a single-acting piston having a longer stroke than a, double-acting piston with which it is associated, these pistons being connected at leverages proportionate to their strokes so that their forces are combined. The double-acting piston alone effects the return stroke of the mechanism. In the modification shown in Fig. 4 both pistons 3, 103 are contained in one cylinder and the hollow piston rod 105 of the singleacting piston 103 encloses the hollow piston rod 5 of the double-acting piston 3 and is connected by a threaded sleeve 107, yoke 108 and rod 109 to the end of the long arm 51<b>, Fig. 3, of a lever 51, to the short arm 51<a> of which is connected the piston rod of the double-acting piston by a rod 9. Reversing valve mechanism 40 contained in the hub of the piston 3 introduces air between the pistons through a strainer cup 7a, the piston rod 5 and a port 12a when the brakes are applied and the pistons are forced apart. The piston 3 is provided with another piston rod 5a passing through the other end of the cylinder. Air passes through the piston rod and by the valve mechanism and a port 11<a> to the side of the piston 3 remote from the piston 103 when the brake is relieved. The valve mechanism is operated by a hollow sleeve 20 connected to the brake pedal and provided with a stop 28 adjusted so that in the release position it maintains the valve mechanism in such a position that both sides of the piston 3 are connected to the partial vacuum of the induction pipe of the vehicle engine, through this hollow sleeve and a flexible connection 62. A connection 62b always maintains a partial vacuum in the space between the piston 103 and the end of the cylinder. The brakes may be applied directly by the valve sleeve 20 when lost motion sufficient to operate the valve mechanism has been taken up. This is brought about by a collar 21, Fig. 4A, which is provided on the sleeve 20 and between which collar and inwardly projecting portions 5b on the piston rod 5a a coil spring 22 is provided the coils of which contact to form a collar when compressed. One set of brakes are connected to the lever 51, Fig. 3, at 9 and another set at 54 at an equal distance from the pivot 57. This lever is pivoted in a hanger 55, pivoted at 56 in order to equalize the action of the two sets of brakes. When all the brakes are connected at one point to the lever 51 the hanger is fixed. A plurality of apertures is provided in the long arm 51<b> to allow adjustment of a connection thereto. In a modification in which the pistons are contained in separate cylinders, on application of the brakes, the valve mechanism introduces air into one end of the double-acting cylinder which is connected by piping to the operating end of the single-acting cylinder. Air is introduced into the other end of the double-acting cylinder to return the mechanism. The single-acting piston is provided with a piston rod passing through each end of the cylinder, one end of the rod being connected to a pivoted lever nearer the pivot of which the double-acting piston is connected. Both sides of both pistons are normally connected to the induction pipe of the vehicle engine.