GB698417A - Improvements in master-cylinders for hydraulic pressure systems - Google Patents

Abstract

698,417. Mastercylinders. DUNLOP RUBBER CO., Ltd. June 13, 1951 [July 1, 1950], No. 16479/50. Class 103 (i). A mastercylinder for pressurizing brake and other hydraulic systems comprises, as shown in Fig. 1, a pedal-operated main piston 8 slidable in a cylinder 1 and having a plunger 13, 14, 15 projecting them from and slidable in a smaller cylinder 2. The cylinder 1 is supplied with liquid from a reservoir through a check valve 23 fitted adjacent a relief valve 22 which lifts to prevent excessive pressure being created in the cylinder 1. In the retracted position of piston 8 shown, the inside of cylinder 1 is in communication through passages 16 and 17 in the plunger part 15 with the interior of cylinder 2 so that as the piston 8 is advanced liquid is forced direct from the cylinder 1 through cylinder 2 and by connection 5 to the brake cylinders or other hydraulic device. When the plunger part 13 enters the cylinder 2 communication between the two cylinders is interrupted and thereafter the plunger transmits pressure at a higher ratio to the actuated device by reason of the smaller effective piston area. In a modified arrangement, the piston has a bore therein within which slides the plunger which is anchored to the opposite end of the cylinder. The bore in the piston is closed and forces liquid through a central passage in the plunger and out through an end connection to the brakes. In a further modification of such an arrangement, as shown in Fig. 3, the internal bore of the main cylinder 45 is stepped, and movement of the main piston causes liquid to be pumped through a connection 51 at the large part of the bore as well as the end connection 48, the two outlets being hydraulically separated when the piston enters the small part of the cylinder bore.