GB808311A - Hydraulic transmission - Google Patents

Abstract

808,311. Rotary engines or pumps. GEROTOR MAY CORPORATION. June 3, 1955 [Dec. 28, 1954], No. 15933/55. Class 110 (2). [Also in Group XXIX] An hydraulic transmission comprises a pump P and a motor M of the sliding-vane type and of similar construction; a pump vane rotor 14 is fast with an input shaft 11 and a motor rotor is fast with an output shaft 18, and the pump and motor communicate through passages 21, 22 in a stationary pintle 20. Passages 21, 22 terminate in ports 25, 25M leading to the rotor centres and having reduced leading and trailing ends, as shown in Fig. 7, to reduce " hammering." The rotor vanes are maintained in engagement with the inner wall of the rotor casing by liquid pressure at the base of the vanes, the liquid being supplied from whichever passage 21, 22 is the pressure line through non-return valves or shuttle valves. If the pressure in the pressure line 21 or 22 becomes excessive, a relief valve opens a passage between the line 21 or 22 and a reservoir 39. To avoid cavitation a minimum pressure is maintained in the suction line 22 or 21 by an auxiliary pump 91 on the input shaft which draws oil from the reservoir and delivers it to the suction line through a relief and a non- return valve. Make-up oil additional to that supplied by pump 91 required in the event, for example, of the relief valves blowing, is supplied to the suction line 22 or 21 from the reservoir through a non-return valve. A fan 115 on the input shaft blows air through cooling tubes 85 provided in the reservoir. The pump rotor casing comprises a ring 31 fast with end walls 32, rotatably mounted in rings 35, 35<SP>1</SP>. The eccentricity of the casing is varied by means of members 122, 123 secured to the rings 35, 351. Member 122 is movable manually by screw-andnut means having a lost-motion connection 119, 120 with the member 122. Member 123 may either be urged by a spring 130 towards the member 122 so that lost-motion is normally taken up, spring 130 bearing against a ram contacting the member 123, or, as shown, the spring bears against a piston 128 connected to the member 123, and the auxiliary pump 91 supplies liquid through a conduit 133 to move the piston to the right to take up the lost-motion in the connection of member 122. If the pressure from pump 91 falls sufficiently, piston 128 moves to the left under the action of spring 130 to return the rotor casing to the neutral, or reverse, position. A braking action may thus be obtained.