GB619090A - Improvements in or relating to devices for controlling the raising and lowering of agricultural implements particularly ploughs - Google Patents

Abstract

619,090. Hydraulic machines. REGIE NATIONALE DES USINES RENAULT. Nov. 19, 1946, No. 34253. Convention date, Oct. 11, 1945. [Classes, 69 (ii) and 135] [Also in Group I] A hydraulic power-lift device for tractormounted implements includes a piston 15 movable in a cylinder 16, the piston being connected to the implements through a bell-crank 12, and a pump 17, which feeds oil to the cylinder through a distributer formed of two members 18, 19, sliding, one inside the other, in a casing 26 in such a manner that relative movement between the sliding members regulates the flow of oil to the cylinder. The casing is divided into four chambers 26<1>-26<4> and the sliding member 19 comprises a sleeve having orifices 30-35 by means of which the chambers are put into intercommunication. The sliding member 18 comprises a double piston 18<1>, 18<2> which is movable by a lever 20 to cover and uncover the various orifices. The sleeve 19 is connected to the bell-crank 12 through a lever 22, pivoted at A, and a rod 23. To raise the implements, oil is pumped from a reservoir, through a pipe 27, orifices 30 and 31, pump 17, orifices 32 and 33, and outlet pipe 26<5>, into the cylinder 16. The resultant movement of the piston 15 moves the sleeve 19 so that the orifices 30-33 are covered, and the tools remain raised. To lower the tools, the double piston is moved to the left, thus uncovering the orifices and permitting escape of oil from the cylinder 16. The device also operates as a depth-regulating device, since variations in the ground resistance to the tools are transmitted as variations in oil pressure to an auxiliary spring-loaded piston 24 carrying the fulcrum A of the lever 22. This causes movement of the sleeve in such a direction as to admit oil to, or permit its expulsion from, the cylinder 16.