Patent GB-901967-A (GB)
Title: Infinitely variable hydraulic transmission gear
IPC: F16H47/04
Filed: 1958-08-25
Abstract: 901,967. Variable-speed gear; clutch control. EBERT, H. Aug. 25, 1958 [Aug. 29, 1957], No. 27249/58. Class 80 (2). [Also in Group XXIX] An infinitely variable hydraulic transmission gear comprises at least one motor unit that is connectable to and disconnectable from a driven shaft by a clutch or other coupling and means for adjusting the motor unit from a stroke position to a neutral position and vice versa, the adjusting means being adapted automatically to operate the clutch so as to connect and disconnect the motor unit when the latter is adjusted to stroke position and to neutral position, respectively. As shown in Fig. 1, the transmission gear includes a pump unit 1, a fixed motor unit 2 and a disconnectable motor unit 3, an engine shaft 4 being geared to a driven shaft 15 by sun-wheel 5, planet gears 6, 11 and sun-wheel 15 and to pump shaft 18 through gears 11, 16 and 17, the shaft 18 being supported by the gear casing 9 and by control-plate 21. The sun wheels 5 and 14, planet wheels 6, 11 and gears 7 and 16 are made pairwise with the same number of teeth and the tooth ratio of wheel 16 to wheel 17 is such that the pump shaft rotates at the same speed as shaft 4 when shaft 15 is held and when shaft 18 is held fast, the shafts 4 and 15 rotate at the same speed. The pump 1 and motor units 23 have pistons 23 operated by swivelling housings or swashplates 24-26 and at the control plate end vertical bores 32 act as suction and pressure lines connecting the pump unit to motors 2, 3. Motor unit 3 acts first on a shaft 35 which can be coupled to shaft 15 by a disc clutch 37 comprising members 36, 38 connected respectively to shafts 35, 15, and associated therewith is a disc brake 44 arranged respectively to free and stop motor 3 when the clutch 37 is engaged and disengaged. The clutch 37 and disc brake 44 are operated by pistons 48 influenced in one direction by fluid pressure produced by a pump 64 and in the other direction by springs 48a, the gear shift being effected at neutral position of motor unit 3, Fig. 6, where pump and motor units are indicated by dotted lines, the swivelling housings having levers 49 carrying pins 50 engaging slots in slides 52, 53 mounted on the casing and having a link connection with a shift lever 60 operated by a piston 63 to move slides 52, 53 to right and left, respectively, and vice versa. When lever 71 is rocked upwardly, a control valve 72 is moved to the right and oil passes from pump 64 by lines 73, 74 to the righthand side of piston 63 to move it to the left. The consequential clockwise movement of lever 60 moves slides 52, 53 to right and left, respectively, the slide slots being so shaped that the stroke of motor 3 is adjusted to neutral while the strokes of of motor 2 and pump retain their previous values. When neutral stroke position of motor 3 is reached a cam 75 on lever 60 moves valve 76 sufficiently to the right for pipe 78 to be closed to atmosphere and pipe-line 77 to be connected to pipe-line 65. The end face of valve 67 is then acted on by oil pump 64 and moved to the right against the action of spring 79 so that the brake coupling is actuated via pipe-line 69. At the same time the coupling 37 is disengaged by connection of pipe-line 68 to venting pipe 80. On further movement of piston 63 in the direction of 1: 1 the gear operates on one motor unit and the reduction is determined by the ratio between the strokes of the pump unit and motor unit 2. The pump unit is then brought to full stroke while the motor 2 remains on full stroke and the pressure of working fluid thereby falls. On further reduction towards 1: 1 the full pump stroke is maintained from the reduction 1: 2 onwards while the stroke of motor 2 is adjusted to zero. The reverse operation of lever 71 moves piston 63 to the right and stroke adjustment and coupling operation take place in the reverse direction. On movement of piston 63 to the right beyond the position shown the full stroke of motors 2 and 3 is maintained. The pump stroke is brought to a negative value at the same time and results in a gear change from forward to reverse. The shaft 35 may act on the clutch member 36 through planetary gearing, Fig. 4 (not shown), or through reduction gearing, Fig. 5 (not shown) and in the latter Figure the pump and motor units are constructed with swivelling drums. In Figs. 8 to 10 (not shown), the piston cylinders are formed as double units and pump and motor units may be arranged in horizontal or vertical alignment or triangularly disposed.