GB549134A - Improvements in hydraulic mechanism for the operation of tractor-drawn agricultural implements - Google Patents

Abstract

549,134. Agricultural implements. BROWN TRACTORS, Ltd., D., MERRITT, H. E., and HULL, C. H. Aug. 19, 1941, No. 10525. [Class 6 (i)] [Also in Group XXIX] In a hydraulic mechanism for raising and lowering tractor-drawn agricultural implements, the control of the pressure liquid led from a supply pump to a pipe a is effected by a piston valve c which is raised to the position shown against the action of a spring t by means of a lever p connected by a Bowden wire o, lever n, and link m to the valve spindle c<SP>3</SP>. A spring-catch s holds the spindle c<SP>3</SP> in raised position. The pressure liquid then passes through a non- return valve e to the cylinder f and raises the piston g which is connected by a link g<SP>1</SP> and lever h to the shaft h' controlling the position of the implement. When this reaches the required position an arm h<SP>2</SP> releases the catch s and the valve c descends under spring action and connects pipe a to the exhaust pipe i thus permitting the pump to run light. The valve still closes a pipe connected to the cylinder f so that the pressure is maintained in the cylinder f at a value which does not exceed the pressure at which a relief valve k opens. The position of valve c is controlled by the engagement of the lever p with a stop r<SP>1</SP>. The lever p is made of flexible material and can be moved past the stop r<SP>1</SP> by flexing it and so opening up the pipe to permit the implement to fall at a controlled speed. Should the operator not release the handle p when the implement is fully raised, excess movement of the shaft h<SP>1</SP> causes an arm u to engage a projection v on the valve spindle and to depress it so as to relieve the pressure.