Patent GB-191019935-A (GB)
Title: Improvements in Machinery for the Transmission or Distribution of Motive Power by Means of Liquids.
Inventor: PITTLER WILHELM VON
IPC: F16H61/42
Filed: 1910-08-26
Granted: 1911-08-24
Abstract: 19,935. Pittler, W. von. Aug. 26, 1909, [Convention date]. Speed - varying mechanism.-A controlling- device for hydraulic change - speed and reversing mechanism for motor-cars &c. comprising a force pump and one or more liquid-pressure motors, is characterized by a balanced piston valve which controls a series of passages leading to the individual motors or to the individual motor working chambers in such a manner that it puts a larger or smaller number of them in communication directly with the pressure chamber or the suction chamber of the pump. Fig. 1 shows a side elevation of an hydraulic change - speed and reversing - gear, Fig. 2 is a longitudinal section through the controlling-device, and the right and left parts of Fig. 4 show different cross - sections. Fig. 6 is a section along the centre line of Fig. 4. Within the casing a, which is partly surrounded by a housing s, containing fluid passages q, q<1>, r, is arranged a tubular piston slide b operated by rods d, d<1>. The valve-chest is provided with a series of passages e, f, g, h, i, j, k. The passage c communicates with the delivery side of the pump P, the passages f, g, h, i lead to the individual motors t or to the individual working chambers of the motors t, and the passages and k serve to conduct the pressure fluid from the motors back to the pump and as a circulating-passage for the short-circuited pump. Two rotary engines t are arranged at either side of the controlling-valve casing. They have each a drum u with two grooves concentrically cut in the face ends. Each groove is divided by two abutments W, w into two separate working chambers V, V<1> and v, v<1>. The passages f, i lead to the chambers V, V<1>, and the passages g, h lead to the working chambers v, v<1>. These working chambers further communicate through passages m, p, and n, o respectively with the passages q, q<1> arranged between the inner valve-chest proper a and the housing s, which communicate through the chamber y with the interior of the casing a, and thus through the openings j, k with the passage r leading to the suction pipe of the pump. When the slide b is in the position shown in Fig. 7, pressure liquid flows through the passages f into the working chamber V in the outer groove of each engine, from which it escapes through the passages m, q, y, k, j, r back to the pump. The other chambers are short-circuited. In the position shown in Fig. 8, liquid passes to the chambers V, v and escapes through passages n, q to the pump. In the position shown in Fig. 9, the fluid is distributed into passages f, g, h. The part passing through the passage works in the second chambers v<1>. In the position shown in Fig. 10. the fluid also passes into the chambers V<1>. This position corresponds to the lowest speed. If the piston is shifted to the position shown in Fig. 11, the pump is short-circuited. This position corresponds with the car slowing down. If the car is to be forcibly stopped, the piston is moved into the position shown in Fig. 12, whereby the current from the motors is throttled at k. The position shown in Fig. 13 corresponds to reversal of the motors, for the motive fluid is fed to the passages q, q<1> through the bore of the piston b. If it is desired to reverse at varying speeds, the casing a is lengthened as shown in Fig. 14. A relief valve may be fitted between the chambers y, r.