Patent GB-1204021-A (GB)
Title: Power-branching hydraulic axial piston type transmission
Inventor: NEUKIRCH JOHANNES
IPC: F16H39/10
Filed: 1968-04-26
Abstract: 1,204,021. Hydrostatic transmissions. J. NEUKIRCH. 26 April, 1968, No. 19873/68. Headings F2C and F2D. A hydrostatic transmission having a pump and a motor of the swash-plate type comprises a pump cylinder block 7 splined to an input shaft 2 and rotatably mounted concentrically within a stationary motor cylinder block 1, a distributer valve 23 and a pivotable support member 14 for the pump and motor swashplates 18, 19 being fast in rotation with an output shaft 5. As shown in Fig. 1 the pump and motor swashplates are mounted at an angle to each other in the support 14 by way of bearings 15, 16 and the support is pivotally adjusted by means of the screw 28 acting on a cranked fork 29 pivoted on the motor cylinder block 1 and engaging a groove in an axially displaceable thrust member 30 which is linked to the swash-plates support member 14. Movement of the thrust member 30 to the right from the neutral position shown increases the transmission ratio by increasing the pump displacement and reducing that of the motor until the motor displacement is reduced to zero to give direct drive. In the modification shown in Fig. 7 the pump and motor swash-plate are individually adjustable, the pump and motor swash-plates 18, 19 being mounted by bearings 38, 39 in supporting rings 40, 42 respectively, which rings are individually pivotable about a common axis in a non-pivotable support member 43 which is fast in rotation with the output shaft 5. The swash-plate are adjusted by an axially movable thrust member 55 which is connected by a link 51 to the pump swash-plate supporting ring 40. The link 51 has a pin-and-slot connection 68 with a lever 65 which is pivoted at 66 to the output shaft and has a pin-and-slot connection 69 with a lever 50 which is pivoted to the motor swash-plate supporting ring 42. The adjustment member 55 is displaceable downwardly from the uppermost position shown, in which maximum reverse ratio is obtained, initial movement of the member 55 reducing the pump displacement whilst the motor displacement remains unaltered, the motor swash-plate being spring biased against a stop and lostmotion in the pin-and-slot connections being taken up, until the pump displacement is zero and neutral is obtained. Further downward displacement of the member 55 increases the pump displacement in the forward direction and reduces that of the motor to increase the transmission ratio until direct drive is obtained. In both embodiments the distributing valve 23 has the pump kidney ports connected to the diametrically opposite motor kidney ports to reduce tilting forces on the valve plate. In the Fig. 1 embodiment the high and low pressure ports communicate with respective concentric grooves in the back of the valve plate which are connected through check valves to a make-up pump. In the Fig. 7 embodiment the high and low pressure ports (which interchange their function for forward and reverse) are connected by a valving arrangement to concentric grooves in the back of the valve plate, and the groove connected to the low pressure port is connected to a make-up pump.