GB617827A - Improvements in or relating to variable speed power transmission mechanism - Google Patents

Abstract

617,827. Hydro-mechanical variable-speed gearing. FORD MOTOR CO., Ltd. Oct. 10, 1946, No. 30250. Convention date, Nov. 3, 1945. [Class 80 (ii)] In a variable-speed gear of the kind in which the transition from first to second speed and from second to third speed takes place automatically by the operation of clutches actuated by fluid under pressure supplied by a pump, the pressure in the pump and therefore, the torque capacity of the clutches is controlled by a relief valve progressively operable at a lower or higher pump pressure as the transmission torque decreases or increases. As shown, applied to a motor vehicle hydromechanical variable-speed gear of the kind described in Specification 615,175, stepped planets 24 ... 26, Fig. 1, mesh respectively a sun 27 connected to a clutch carrier 19, a sun 28 on an intermediate shaft 13, and a driven sun 29. In first speed, the sun 28 is driven through a hydraulic coupling 16, 17 and a one-way clutch 18. In second speed, a hydraulically-operated clutch 21 is engaged to byepass the coupling and drive the sun 27, the clutch 18 overrunning. A one-way brake 32 prevents reverse rotation of the planet carrier 22 in both these speeds. For third speed, which is direct drive, a hydraulically-operated clutch 23 between the members 19, 22 is additionally engaged to lock up the gearing. Pressure fluid for the clutches 21, 23 is supplied by a pump 33 through conduits 37, 38 and is controlled by a valve 41 regulated by a centrifugal governor 42 on the member 19. A spring-loaded relief valve 46, Fig. 2, connects the pressure and intake chambers 36, 35 of the pump 33. Pressure fluid, via a bore 52, acts on the right-hand end of the valve member 46 to move it to the left and connect the chambers 36, 35 when a predetermined operative pressure is attained. To vary this operative pressure in accordance with the torque requirements of the clutches 21, 23 at any particular time, the left-hand end of the valve member 46 coacts with a bellows 65 to which engine inlet manifold suction is admitted via a pipe 73 so as to modify the action of the valve spring 62.