GB581672A - Improvements in or relating to hydraulic power transmission systems - Google Patents

Abstract

581,672. Hydraulic machines. KEELAVITE CO., Ltd., and JOHNSON, E. H. Oct. 11, 1944, No. 19567. [Class 69 (ii)] In hydraulic power transmission systems in which a rotary or other pump C- supplies liquid to motors E, J, one or more air-collecting chambers, which maybe constituted by the pump or motor casings or a separate chamber G, are provided with air bleed valves L, M, P, the arrangement being such that at starting, during idling, or whenever the pressure in the system is low, the valves permit escape of air from the chambers and entry of pressure liquid thereinto. Bleed valve L is mounted on the pump C which may be of the kind described in Specification 551,991, [Group XXVI], having a casing containing liquid maintained at a pressure between inlet and delivery. The valve comprises a differential piston L<1> having its small end constantly subjected to pressure in the discharge pipe D through pipe L and valve L<3>, and its other end to the chamber pressure through port L<2>. At low discharge pressures, the valve moves to the right and permits escape of air from the chamber to the suction reservoir A through port C<1>, and entry of liquid from pipe D through port C<2>. At a predetermined pressure, the valve moves to the left and cuts off ports C', C2. Valves M and P are actuated by the discharge pressure against springs. Should the pump C be reversed, D becomes the suction pipe and K the discharge, but both pipes are connected to the valve L through valves L<3>, L<4> in such a way that the small end of valve L<1> is always subjected to the discharge pressure and functions similarly for both directions of discharge. Similarly, valve P is connected to pipes F and K through valves Q<4>, Q<5> so arranged that the higher pressure always acts on the valve in opposition to the spring while air is ejected into the low pressure pipe.