Patent GB-470069-A (GB)
Title: Improvements relating to agricultural implements attached to tractors
IPC: A01B63/111
Filed: 1936-02-05
Abstract: 470,069. Implements for working land; tractors. FERGUSON, H. G. Feb. 5, 1936, No. 3440. [Class 6 (i)] [Also in Group XXXI] In a tractor having a pressure-fluid control unit, including a pump, for lifting and controlling an attached agricultural implement, a valve is provided on the inlet side of the pump for controlling the admission of fluid so that the supply may be varied, cut off, or discharged in accordance with requirements. The power-operated unit may consist of a hydraulic ram 7 operated by oil from a pump 12 driven continuously from the tractor engine. The connecting rod 7a of the ram piston is connected to an arm 8a on a rock-shaft 8 on which are arms 9 connected by rods 10 to the lower links 6 of the linkage connecting the implement frame 4a to the tractor. The oil passing from the pump 12 lifts a ball valve 34, Fig. 4, and passes either to the pump outlet or to a byepass passage 35 leading to restricted ports 23 in a sleeve in which works a piston valve 14 the movements which are controlled by a hand-lever 15, a spring 14a, and a dash-pot 30. The valve 14 controls the admission of oil to the pump through ports 21 as well as the outflow through the byepass 35. When the lever 15 is pushed forward it turns a lever 17 about a fulcrum 20 and thus operates a rod 18 and a lever 19 to move the valve 14 so as to uncover the ports 23 and allow the oil to escape and the implement 4 to fall slowly. When the implement engages the ground the upper link 5 of its draught linkage pushes forward a spring- controlled rod 25 which is connected through a pivoted lever 26 with a sliding rod 27 carrying the fulcrum 20. Movement of this fulcrum allows the valve 14 to close the ports 23. When the implement reaches the desired depth the valve 14 covers both the ports 23 and the ports 21, the depth of work thus being regulated by the position of the lever 15. The implement is raised by pulling back the lever 15 and thus uncovering the ports 21 and allowing oil to flow to the pump. As the implement rises the rod 25 is moved by the spring 29 and the valve 14 moves so that the ports 21, 23 are all closed when the implement is fully raised. When the implement has been raised to a predetermined height it is automatically stopped, the ram piston contacting with or projection on the lever 17. When the implement is in work an increase in the draught will automatically cause a movement of the rod 25 and consequential movement of the valve 14 to open the inlet ports 21 and raise the implement. When the draught reaches the predetermined amount again the rod 25 and valve 14 move back again to normal position. If the draught is reduced the ports 23 will be opened automatically and the implement will descend until the draught becomes normal. A safety valve 32 may be provided on the ram cylinder, and this may be opened automatically by excessive movement of the rod 27. The lever 19 may be in two parts hinged together, a spring serving normally to hold the two parts in position but yielding under excessive load. Specifications 253,566, [Class 6 (i)], and 470,087 are referred to.