GB681546A - Improvements in hydraulic motors and hydraulic transmission systems for vehicles - Google Patents

Abstract

681,546. Rotary hydraulic motors. GOUNDRY, R. N. Jan. 23, 1950 [Jan. 27, 1949], No. 2275/49. Class 110(ii) [Also in Groups XXIX, XXXI and XXXIV] The invention relates to a hydraulic motor of the type comprising a vaned rotor mounted within a stator and to a hydraulic transmission system for vehicles. The motor also includes a clutch for coupling the rotor to a member to be driven thereby, a selector valve for controlling the supply of liquid under pressure to the motor and a piston controlled by hydraulic pressure supplied to it under control of the selector valve which maintains the clutch engaged when the selector valve is in either a forward or reverse drive position, but disengages the clutch when the valve is in neutral position. Fig. 1 shows a vehicle hydraulic transmission comprising gear pumps 10 located one at each side of the vehicle behind the engine. These pumps supply oil or other liquid under pressure through pipes 11 to hydraulic motors 21 each associated with a rear driven wheel of the vehicle under the control of selector valves 18. If it is desired to drive the front wheels of the vehicle as well as the rear wheels a further selector valve and hydraulic motor will be associated with each front wheel. Fig. 8 shows a perspective view of one of the selector valves. The pressure pipe 11 is connected to an inlet connection 82 and the outlet connection 84 is connected to a return line 12. When the valve is in the position shown (i.e. the neutral position), a port 98 in a rotatable valve member 76 connects a port 91 to the return line and this relieves the pressure acting on a piston 59, Fig. 3, and releases a clutch 53, 54 and thus disconnects the associated motor 21 from its driving wheel. When the valve member is rotated in a clockwise direction the port 94 connects an inlet space 83 with an outlet space 89 and liquid is thus supplied to one side of the motor and the other side of the motor is connected to return by means of the port 95 and spaces 85, 88. At the same time a port 96 registers with a port 90 so supplying pressure to act on the piston 59 and engage the clutch. Rotation of the valve in the opposite direction reverses the supply and return lines to the motor and maintains the supply of pressure to the piston. As shown the selector valves are interconnected and coupled to a valve 16 which is opened whenever the selector valves are in neutral position or the brakes are applied. The trip valve comprises two independently adjustable ported plates one connected to a lever 80 and the other connected to a brake pedal 103. Figs. 2 and 3 shows the hydraulic motor. As shown rollers 38 engage a cam track 39, 41, 44, to rock vanes 34 into and out of chambers 29 in a stator 23. At the moment that a vane starts to move from its aligned towards its sealing position a nick (not shown) in the edge of the vane comes into register with a narrow groove, also not shown, in the contacting face of the cavity 47 in the rotor to form a duct by which pressure liquid may pass from the inlet port to the portion of the cavity 47 behind the trailing edge of the vane so balancing the pressures on opposite sides of the vane. A rotor 24 carrying the vanes drives through pinions 49 a sleeve 56 carrying the clutch member 53, the clutch member 54 being carried by the hub of the vehicle wheel. Brake shoes 105 are operated by a sleeve 107 having cam surfaces 108. The sleeve is moved positively to apply the brakes by means of a wedge 111 interposed between a roller 112 on the sleeve and a pair of rollers 113 only one of which is shown in Fig. 2. The wedge is connected to a piston which is moved in a cylinder by hydraulic pressure. Provision may be made for the brake pedal to move the sleeve 107 mechanically in the case of failure of the hydraulic pressure. A piston is arranged in the selector valve aligned with the pressure inlet 82 and loaded in opposition to the pressure by a spring. The rear of the piston is connected to the return line. The piston serves to take up shock loads. Suction may be produced in a reservoir 13 by an air line 17 to the carburetter via a non-return valve not shown.