Hydro-mechanical compound transmission

1,114,167. Change-speed gear. VOITH GETRIEBE KOMM. GES. 26 Nov., 1965, No. 50428/65. Heading F2D. A hydromechanical transmission for a rail vehicle includes at least two turbo transmitters capable of being alternatively engaged and disengaged, followed by mechanical multistage gear-boxes, at least one two-stage gearbox operable by mechanical clutches being arranged between each transmitter and a common output shaft, the respective stages being arranged for opposite directions of rotation with different speeds of the output shaft, the forward and reverse ranges of the respective gear-boxes having different transmission ratios. In the arrangement shown an input shaft 1 drives an intermediate shaft 4 through spur gears 2, 3, the shaft 4 driving the output shaft 25 through dog clutch-operated forward and reverse gear trains 15, 16; 17, 18, 19 and 20, 21; 22, 23, 24, the respective forward and reverse ratios being different. The shaft 4 is connected to the impellers 7, 10 of a pair of similar hydraulic torque converters 5, 6, the runners 8, 11 of which are connected to hollow shafts 13, 14 carrying the pinions 15, 17, 20, 22. A control valve 30 may be positioned for filling either of the converters and simultaneously emptying the other. Numerous embodiments are described, including arrangements in which the torque converters are disposed between the pinions 17, 20, on opposite sides of pinions 2, 3, and externally of pinions 15, 22, Figs. 2, 3, 7 (not shown). In the latter case a pair of hydraulic couplings may be mounted between pinions 17, 24 with a common impeller connected to shaft 4 and their respective runners connected to the hollow shafts 13, 14. A further arrangement, Fig. 9 (not shown), includes an additional forward ratio in each range. The converters may be of different capacities, Fig. 15 (not shown), or rotate in opposite directions, Fig. 17 (not shown). Oneway clutches may be substituted for the dog clutches in the upper gear stages to enable these ratios to be engaged during shunting by changing over the filling of the torque converters without bringing the vehicle to rest.