Patent GB-747341-A (GB)
Title: Improvements relating to hydro-mechanical reversible gear
IPC: F16H3/00
Filed: 1951-05-03
Abstract: 747,341. Hydraulic couplings; fluid pressure servomotors. VOITH GES., J. M. May 3, 1951 [June 12, 1950], No. 10444/51. Classes 69 (2) and 135. A hydro mechanical reversible gear comprises two turbo circuits 7, 8 capable of being filled and emptied and arranged respectively in the transmission path for forward and reverse drive, the circuits being provided with ring valves 37, 38 or adjustable vanes or other devices for controlling their transmission capacity, control means operable through a control lever which is so arranged that movement of said lever from a middle or neutral position in one direction or the other effects filling of one or other of said circuits and also effects adjustment of the associated ring valve 37 or 38; the gear further comprises additional automatic control means operable in dependence upon the output speed which means below a predetermined output speed fills or maintains filled the two circuits independently of the position of said control lever. A driving shaft 1 is coupled to a shaft 4, through gears 2, 3, to which are secured the impellers 5, 6 of converters 7, 8 the turbines 9, 12 of which are connected to an output shaft 16 through gears 10, 11 and 13, 14, 15. A filling pump 17 delivers fluid to the converters 7, 8 through valves 19, 21 and pipes 18<SP>1</SP>, 20<SP>11</SP>. The valves 19, 21 are controlled by valves 27, 28 which control the supply of pressure fluid from the pump 17 by pipe 24 to either of pipes 22, 23 which communicate with the upper side of the valves 19, 21. The valves 27, 28 are actuated by cams 29, 30 on a common shaft operated by the control lever which in a central position holds both valves open and in which position independently controls a valve 26 which shuts the connection from the pipe 24 to both pipes 22, 23, whereby both converters are emptied. The valves 27, 28 are biased to the open position by springs 31, 32 and when one or other is released by a cam 29 or 30 it does not close until pressure in a pipe 34 connected to a measuring pump 33 on the output shaft 16 overcomes the spring. When the valve 27 or 28 is closed, pressure supply to the top of valve 19 or 21 is cut off and the pipe 22 or 23 exhausts through 35 or 36, whereupon the converter controlled by that valve is emptied. The ring valves 37, 38 are actuated by servomotors 51 which are controlled by a lever 43 operated by the control lever. When both turbo circuits are filled these ring valves 37, 38 alone control the speed and direction of the output shaft 16. When the gear is operating at speed, i.e. when one turbo circuit only is filled, braking may be effected by inserting the associated ring valve. If further braking effect is desired a separate braking lever may be operated which causes the filling of the other turbo circuit, the ring valve of which is already in the circuit closing position. The servomotors 51 comprises a piston sleeve 40 and a valve 42 actuated by the lever 43 controlling pressure supply from the pump 17 to the top of the piston sleeve 40. The sleeve 40 has rack teeth 401 which engage teeth 52 on the ring valve which is formed with helical grooves 53 engaged by fixed pins 54 to cause axial movement of the ring valve. Specification 681,594 is referred to.