Patent GB-726336-A (GB)
Title: Improvements in or relating to hydraulic control valves
Inventor: TOMIK GEORGE ALOIS
IPC: F16K11/078
Filed: 1953-02-27
Abstract: 726,336. Interconnected valves. INTERNATIONAL HARVESTER CO. OF GREAT BRITAIN, Ltd. Feb. 27, 1953, No.5541/53. Class 135. This invention relates to hydraulic control valves such as described in Specification 725,288 in which a single control lever 28 effects angular movements of a valve plunger 22 for selecting one or other or both of a pair of hydraulic rams or the like for operation and also effects axial movements of the plunger for effecting operation of the selected ram or rams. According to the invention, a valve attachment is provided for delaying .the operation of one of the rams until the other has completed its movement, the said attachment comprising a check valve element 8 loaded so as to open at a predetermined pressure and arranged so as normally to prevent return flow from the ram cylinder to which it is connected and mechanism operated by the control lever so that when the latter is positioned to lift both rams, the check valve remains closed until opened by the build-up of pressure consequent on the ram to which it is not connected having completed its stroke and so that when the control lever is positioned to lower the rams, the check valve element is mechanically displaced from its seating. The invention is particularly applicable to the control of the front and rear implements of agricultural tractors in which it is sometimes desirable to operate the rear implement after the front implement. The valve attachment comprises a spring-loaded ball valve 8 arranged in a casing 1 bolted to the casing 2 of the main control valve. The valve 8 may be mechanically displaced from its seat by a plunger operated on by a push-rod 19 guided at its upper end in a hole in the cap 21 of the main valve. The casing 1 has a connection 4 leading to the bore of the valve plunger 22 and a connection 12 leading to the lifting end of the ram cylinder of the rear implement. A passage 25 with a fitting 26 leads to the lifting end of the front implement ram. The lowering ends of the front and rear rams are supplied by connections 27, 27a respectively. The control lever 28 has a yoke 29 pivoted to an extension 31 of the valve plunger 22 by a pin 30 and to a link 32 by a pin 28a. The link 32 is adjustably clamped on a spindle 33 mounted in bearings 34 and has fixed to one end a substantially horizontal arm 36. The bearings 34 and the spindle 33 are carried on a bushing 35 angularly adjustable on an extension 21a of the valve cap 21. The bushing may be clamped in its adjusted position by a set-screw 37. The control lever 28 has three positions of angular adjustment A, B, C about the axis of the valve plunger 22, these corresponding to operation of the rear implement only, operation of both implements, and operation of the front implement only. The lever 28 has four positions D, E, F, G for axial adjustment of the valve plunger 22, namely, neutral position D, position E for lifting one or both implements, position F for permitting an implement to " float " or lower under gravity, and position G for lowering one or both implements under pressure. When the lever 28 is in position B, the middle of the arm 36 lies over the push-rod 19, but in position A the free end of the arm overlies the push-rod. Upward and downward movements of the lever 28 from the neutral position D both cause a downward movement of the arm 36, but such movement is less when the lever is moved to position E than when it is moved to position G with the result that with the lever 28 in position B, the clearance 40 between the arm 36 and the push-rod 19 is not taken up in the first case and is taken up in the second. Thus the lifting of the rear implement can be delayed, but its lowering takes place substantially at the same time as the front implement but is somewhat slower due to the slight throttling produced by the open check valve 8. When the lever 28 is turned to position A, however, to operate the rear implement only, the arm 36 depresses the push-rod 19 in both positions E and G so that no delay arises in either lifting or lowering the rear implement by itself.