Patent GB-822403-A (GB)
Title: Improvements in infinitely variable hydrostatic gears
IPC: F16H39/08
Filed: 1956-08-29
Abstract: 822,403. Change speed gearing. WOYDT, E. Aug. 29, 1956 [Oct. 18, 1955], No. 26382/56. Class 80 (2). [Also in Group XXIX] A continuously - variable hydrostatic variable - speed gear has the pump and motor bodies rigid with the driven shaft, the pump pistons being driven by the driving-shaft through epicyclic gearing and the motor pistons being driven by the driving-shaft through a countershaft and another epicyclic gearing, the planet pinions of the two epicyclic gears being journalled on the respective pump and motor bodies. A driving-shaft 1 drives a countershaft 4 by gears 2, 3, the countershaft 4 carrying a gear 5 drivable through a freewheel 6, and a dog clutch element 7. The shaft 1 also carries a gear 8 meshing with planetary pinions 9 on two crank-shafts 9a of a pump unit 10 such as described in Specification 811,864, [Group XXIX], and a phase-changing straight and helical spline coupling 14, 14a, 14b driving an internally-toothed gear 13 meshing with planetary gears 11 on two crankshafts 1 1a of the pump 10. The pistons of the four pumps within the pump unit 10 being interconnected with the cranks on shafts 9a, 11a such that relative rotation of the gears 9, 11 changes the strokes of the pistons. Secured to the pump body 10 by connecting pieces 15 and 21 are two motor units 20, 22 of similar construction to the pump unit 10, also secured to these motor units is the driven shaft 28. The cranks of the motor units are driven by crank-shafts 12a, 25a by planetary gears 12, 25 meshing with internally and externally toothed gears 17, 18, respectively, the gears 17, 18 having a phase-changing coupling 16, and being coupled to a gear 27 meshing with the gear 5. An extension 30 of the shaft 28 carries a gear 31 and a dog clutch element 39, the gear 31 meshes with a gear 32 clutchable by dog clutch elements 33, 34 and sleeve 35 to a shaft 36 having a gear 37 meshing with a gear 38 on an output shaft 42. The shaft 42 may be coupled to the shaft 30 by a dog clutch 39, 40, 41, similarly the shaft 36 may be coupled to the countershaft 4 by the clutch members 7, 35, 34. The timing of the cranks driving the motor unit 20 is arranged 50 degrees in retard of the timing of the motor unit 22 such that at minimum stroke of the motor unit 22 it is possible to change the operation of the unit 22 from motor to pump operation by a slide valve within the piece 21 controlled by a pin 29 projecting from a slot in the shaft 28. Under such conditions in which both units 10 and 22 operate as pumps and unit 20 as a motor a much higher speed is obtainable. In operation the drive from the driving-shaft 1 is divided into a drive in the countershaft 4 and a drive through the epicyclic gears 8, 9, 13, 11 to the pump 10. The countershaft 4 provides the reaction for the epicyclic train 18, 25, 17, 12 through the gears 5, 27 and freewheel 6, and the power output from the pump units 20, 22 is transmitted to the shaft 30. Axial movement of the couplings 14, 16 provides the continuously variable speed across the pump/motor unit, the ratio obtainable being augmented by the dog-clutch controlled gears 31, 32 and 37, 38 to provide a wide continuously variable speed range at the output shaft 42. Specification 778,876, [Group XXIX], also is referred to.