GB585939A - Improvements in and relating to hydraulically operated coupling means for the attachment of agricultural implements to tractors - Google Patents

Abstract

585,939. Agricultural implements. EWING, R. W. C. Aug. 11, 1944, No. 15367. [Class 6 (i)] [Also in Groups XXIX and XXXII] In a hydraulically operated coupling means for raising or lowering an agricultural implement connected to a tractor, a power piston 3, Fig. 1, on the tractor frame or tow-bar rotates a shaft 3c having at each end an arm 3e connected to links 3f, 3g, the arms 3g being pivotally connected to the frame of the implement whilst a further link, not shown, is connected to the cover of a casing 1, housing the power operated means, and to a braced upright secured to the implement frame. The casing 1 contains a pump 4, the power piston 3 in a cylinder 2, and a control valve 12, Fig. 4, and non-return valve 16 in a casting attached to the cylinder 2. The control valve is provided with a flange 15 which is raised by the skirt of the piston 3 at the top of its stroke to cut off the supply of fluid to the power piston by obscuring a port 10 leading to a chamber 11 housing the non- return valve 16. A hand-lever 20 is depressed when the links are to be raised, the lever moving the control valve downwardly until the port 13 therein registers with ports 9, 10 the pressure fluid flowing through pipe 7, ports 9, 13, 10 to chamber 11 and thence through non-return valve 16 and pipe 19 to the bottom of cylinder 2. When the piston reaches the top of its stroke its skirt contacts the flange 15 to raise the control valve 12 and automatically cut off the pressure fluid from the cylinder 2 and divert it to the sump through a recess 14a in the control valve. The links are lowered into an adjusted position by raising the lever 20 to dislodge the non-return valve 16 from its seating, the fluid from the power cylinder passing through a throttling orifice 20c in the control valve to regulate the speed of descent of the piston.