Patent GB-925601-A (GB)
Title: Improvements in multi-position fluid motors
IPC: B60T15/04
Filed: 1960-05-25
Abstract: 925,601. Fluid-pressure servomoto rcontrol systems; hydraulic apparatus. WESTING- HOUSE AIR BRAKE CO. May 25, 1960 [May 26, 1959], No. 18404/60. Classes 69 (2) and 135. With the handle 90 of a rotary control valve 3, Fig. 1, in the neutral position N, Fig. 2, the piston-rod 2 of a multi-position fluid motor 1 is urged into the corresponding position N, shown, by fluid from a reservoir 4 flowing into chambers 30, 39, whilst chambers 40, 20 and 6 are connected to atmosphere. The rod 2 may be connected to operate a vehicle power transmission, not shown, when the valve handle is moved to position F1, the chambers 20 and 19, Fig. 1, are vented, the latter being interconnected by ports 18, and chambers 30, 39, 40 and 6 are pressurized whereupon stop pistons 13, 14 remain in the neutral position shown, whilst a piston 15 travels rightwardly until it abuts a stop 121; at the same time, the power piston 16 moves leftwardly in opposition to a spring 45 until it abuts piston 15 and the rod 2 adopts the F1 position. Upon turning the valve handle 90, Fig. 2, into the F2 position chamber 40 is vented so that the power piston 16 travels leftwardly against the action of the spring 49 and carries with it the piston 15 until the stem 31 of stop piston 14 is contacted at which point the rod 2 is in the F2 position. To move the rod 2 to the F3 position the control valve is correspondingly adjusted whereby chamber 39 is now vented whereupon the power piston 16 moves further to the right, taking with it the piston 15 and stop piston 14 in opposition to the spring 49 until the piston 14 abuts the stem 23 of the other stop piston 13. To complete the leftward travel of the power piston 16 the control valve is moved into the position F4 so venting chamber 30, whereby all the pistons are translated leftwards by the pressure in chamber 6 until lugs 29 and stop piston 13 contact an end plate 9. The control valve may now be adjusted to select any of the positions F3-N for the rod 2 or either of two reverse positions R1, R2. A lost-motion connection 36 is provided between stems 31 and 23. Assuming the valve and rod are in the N position, then upon adjusting the former to the R1 position chambers 40 and 6 are vented and chambers 30, 39, 19 and 20 are pressurized so that the piston 15 is held against the stem 31 and the power piston 16 is urged leftwardly against the spring 49 until it abuts a stop 21. With the valve in the R2 position the chambers 19, 20 and 40 are open to pressure fluid, whereupon the power piston 16 travels rightwardly, carrying with it its cylinder 17, the piston 15 following until it contacts a stop 121. The control valve may now be adjusted to cause the rod 2 to move by steps or directly into any of the other six positions. The spring 49 is connected to the rod 2 by plates 62, 65, the latter being attached to the rod and a cup member 59, which are interconnected by pins 69; the spring 49 is contained between the plates 62 and member 59 and any movement of the power piston from the neutral N position is resisted by the spring, so that if, for any reason, pressure fluid is unavailable, the piston 16 and rod 2 are automatically returned to the neutral position. In other forms, the rod has six, five or three positions depending upon the number of pistons 13, 14 and 15 which are omitted.