GB818984A - A variable ratio power transmission apparatus - Google Patents

Abstract

818,984. Variable-speed gearing. REINERS, W., and WIGGERMAUN, G. Aug. 18, 1955 [Aug. 18, 1954], No. 23839/55. Class 80 (2). A variable-speed gear with positive engagement of toothed wheels has an auxiliary gear which controls the speed of a plurality of intermediate shafts. In the embodiment of Fig. 1 the input shaft 2 is coaxial with the output shaft 3 and may be connected thereto by a dog-clutch 6. The intermediate shafts 4a, 4b are parallel to the shaft 3 and are splined to receive slidable gears 9a, 10a, 11a, 12a and 9b, 10b, 11b, respectively, which are engageable with gears 9, 10, 11, 12 rigid with the output shaft 3. The gears 9a and 9b, 10a and 10b, 11a and 11b are of equal size and are of such diameters to give a set of ratios differing by a constant k when engaged with the respective gears on the shaft 3. The intermediate shaft 4b is always in driving connection with the input shaft 2. Each intermediate shaft 4a, 4b is connected to the inclined plate of swash-plate hydraulic pump 16a, 16b, respectively, the inlets and outlets of the two pumps being connected together by conduits 22 and the pump 16b being tiltable to control its output from +ve to - ve. With the pump 16b in the neutral position, as shown in Fig. 1, drive from the shaft 2 will rotate the pump and the shaft 4b but the pump output will be zero and the shaft 4a will be locked, allowing engagement of gear 9a with gear 9 on the output shaft 3 which will then be locked. Movement of pump 16b from zero to the +ve range will promote an hydraulic drive to the intermediate shaft 4a and rotation of shaft 3. When the pump 16b has been moved to the limit +ve position. the shafts 4a, 4b will rotate at the same speed and thus allow synchronized engagement of gear 9b with gear 9 to provide a power path through these gears in addition to that through the hydraulic system. The gear 9a can now be disengaged and the pump returned through an angle α to produce a speed relation between shafts 4a, 4b equal to the constant k and thus allow synchronized engagement of the gear 10a. Increasing the angle of the pump 16b increases the speed of shaft 4a, and shaft 3, until at full + ve the gear 10b can be engaged to provide the second gear speed of shaft 3. These steps can be continued, if desired, until top speed is attained and the dog clutch 6 engaged to provide a direct drive, the pump being returned to the 0 position. Similar reversed operations are used to change downwards from direct drive through the intermediate ratios to the locked or free state of output shaft 3. From this state, movement of the pump 16b in the - ve direction will produce reverse rotation of the shaft 4a and engagement of gears 9a, 9 will give reverse rotation to the shaft 3. In modifications both pumps are tiltable and one or more differential gears are included in their drive to reduce the number of operations performed on a change of ratio and to provide an increase in the number of ratios without increasing the number of gears in the countershaft gearing. In these modifications a reverse gear train is provided, which can also be engaged simultaneously with the low ratio to provide a positive lock for the output shaft 3.