Patent GB-893074-A (GB)
Title: Hydrostatic drive
IPC: F16H61/46
Filed: 1958-12-02
Abstract: 893,074. Hydraulic transmission of power. PATRA, PATENT-TREUHAND-ANSTALT. Dec. 2, 1958 [Dec. 4, 1957], No. 38856/58. Class 69 (2). [Also in Groups XXX and XXXI] A flow divider for an hydraulic transmission comprises a pump device having a common supply conduit leading to at least two inlets of the device which serves to divide the supply into a similar number of outlets for respective hydraulic motors, and externally-adjustable means acting directly on the device to regulate the ratio of the amounts of liquid delivered to the outlets. The transmission may be incorporated in a vehicle to compensate for the different angular velocities of the wheels as the vehicle is driven around a curve, or in a crane to compensate for the changes in the centre of gravity of the crane during movements of the jib and counterweight. Several flow dividers may be incorporated in a transmission for a vehicle which has liquid motors connected to a capstan, wheels or chains, and, in the case of an amphibious vehicle, a screw propeller, the sizes of the dividers being different depending on the output power of the motors. In the embodiment shown in Fig. 1, the liquid from a pressure pump is supplied to the rotors 14 of the divider through pipes 7-11 and is supplied to the separate motors through pipes 12. The rotors are carried by shafts 17 mounted in bearings 18 in eccentrics 19 which have toothed quadrants 20 engaging gears 21 connected to levers 24, 25, 27 pivoted to a common link 27, the levers having lengths depending upon the control to be exercized by the respective rotors. The rotors have sliding vanes 15 and the shafts 17 are interconnected by gearing so that, if the eccentric of one rotor is positioned such that the space 28 between the rotor and its housing is circular, that rotor is driven by the other rotors and acts as a pump. If all three rotors are positioned so that all the spaces 28 are circular, no out-of-balance forces are applied to the rotors which therefore remain stationary and do not pass liquid to the motors. In another embodiment in which a flow divider with a single rotor 37, Fig. 3, supplies liquid to two motors, the divider consists of pipes 44, 45 which are connected to the pump and pipes 46, 47 which are respectively connected to the motors. The housing 35 of the divider has an elongated bore 36 in which the rotor 37 is carried on a shaft 42 rotatably mounted in an eccentric having a toothed quadrant engaging a gear. Movement of the excentric varies distances S1 S2 to control the ratio of liquid supplied to the pipes 46, 47 and hence the motors. The divider shown in Fig. 3 may be disposed between a pump 51, Fig. 4, driven by a motor 50 and motors 61 driving the rear wheels 60 of a vehicle. The rotor 63 of the divider is connected by links 64, 65 to the steering mechanism of the vehicle and, when the vehicle is driven around a curve, causes more liquid to be supplied to the verticle wheel than the inside wheel. The divider also prevents the possibility of one wheel slipping. The return conducts 70, 71 from the motors are provided with throttle valves 72, 73 which are actuated by a handle 74 to operate as brakes. The pressure in the conduits is indicated on instruments 75, 76 and automatic relief of the pressure is provided by valves 79, 80. The liquid passes from the throttle valves through a cooling device 82 to a reservoir 83. The flow dividers may be incorporated into the drive of a 4-wheel drive vehicle or an excavator and, if the load is accidently removed from any one of the driven members, the dividers prevent free-running thereof. In the case of an amphibious vehicle, the divider controls the change of drive between the screw propeller and wheels as the vehicle enters or leaves the water. When applied to a vehicle having motors driving a capstan, wheels or chains and a screw propeller, a common divider may be connected to the motors driving the capstan and wheels or chain, and this divider connected to a separate divider for the motor driving the screw propeller.