Patent GB-704603-A (GB)
Title: Improvements in or relating to load shifting or load lifting attachments for tractors
IPC: A01D87/00
Filed: 1949-03-14
Abstract: 704,603. Agricultural implements. FERGUSON, Inc., H. March 14, 1949 [March 13, 1948; July 3, 1948], Nos. 6864/49 and 6865/59. Class 6 (1). [Also in Group XXX] In a tractor T provided with a source of pressure fluid, a hydraulic actuator supplied from said source, and a draft linkage trailingly pivoted from its rear for vertical swinging, an attachment for load shifting or lifting comprises a supporting and elevating device, means for connecting said device to the draft linkage, and an auxiliary piston and cylinder type hydraulic actuator carried by the connection means so as to be movable bodily therewith, said auxiliary actuator being connectible to the source of pressure fluid and adapted to give to the device a movement additional to that given by the draft linkage. As shown, a pair of auxiliary pistons and cylinders 51, 50 (one on each side of the tractor) are arranged to shorten the length of connections 42 between the trailing links 10 and the lifting booms 33 so as to give an additional lift to the booms. The combined piston area of pistons 51 is made larger than that of the piston 18 of the main actuator cylinder 19 and the mechanical advantage of the auxiliary actuators is greater than that of the main actuator so that a large initial lifting force is applied by the auxiliary cylinders 50 to break away a load from the ground should it be sticking thereto, e.g., through frost, while at the end of this short lift the main actuator takes over and elevates the load to the full height. The fluid pump 22 delivers fluid to the three cylinders by parallel connections through a valve 23 controlled by a quadrant lever 26 through an eccentric 28 and floating lever 30. Valve 23 has a feed, a neutral and an exhaust position corresponding to lever 26 being in the vertical, inclined or horizontal position respectively. When lever 26 is moved to the feed position, however, fluid flows into cylinder 19 only until the emerging piston 18 strikes the floating lever 30 which moves valve 23 to the neutral position thus providing automatic cut-off. Lever and linkage apparatus.-At each side of the tractor, a link 44 is pivoted at its upper end to a bracket 46 secured to rear axle 11, the pivot 45 being aligned with the pivotal axis of trailing links 10. A second link 48 is pivoted at its rear end to the rear end of trailing link 10 and at its front end at 43 to the lower end of link 44 thus forming a rigid triangle freely mounted at 45. The pivotal connection 43 also freely supports the cylinder 50, the piston 51 of which is connected by a long slender rod 42a to a pivot 41 on a rigid cantilever formed by the boom 33, bar 38 and upright 39 and mounted for swinging about pivot 34 on a bracket 35 secured to the tractor front axle, a similar set of parts being provided on each side of the tractor. Booms 33 are pivotally connected at 88 to a tipping fork consisting of an upstanding shield 36 and spaced horizontal tines 37. In the fluid control system for the cylinders 19 and 50 a valve 53 is provided for giving a fast drop to the booms 33 by constituting an extra exhaust passage. This is accomplished by means of a plunger 55 positioned so as to be depressed when lever 26 is moved to the horizontal position, plunger 55 being normally held in its position by a spring 56. Specification 470,069 is referred to. the depression of a lever 18 accessible to the operator. A hook 25 maintains the lever in its depressed condition. Specification 675,071 is referred to.