Patent GB-1416230-A (GB)
Title: Tractor-mounted mower
IPC: A01D34/28
Filed: 1973-07-04
Abstract: 1416230 Tractor mounted mower DEERE & CO 4 July 1973 [6 July 1972] 31911/73 Headings A1F and A1P A cutter bar mower is mounted on the three point hitch of a tractor so that raising of the hitch causes the cutting blade to rotate around a horizontal pivot thereby causing the blade to move clear of the ground. The mounting comprises a main frame 24, connected to the tractor hitch and in which is mounted pivotally a subframe 36. The forward end of the subframe is connected to the main frame via a chain 42, which is also connected intermediate between the two frames to the draw bar 20 of the tractor. This has a dual purpose, firstly to limit the extent to which the main frame can be lowered, and secondly to cause the subframe to rotate relative to the main frame when the latter is raised or lowered by the tractor hitch. Also attached to the main frame is a yoke 50 which holds a pivot 52 to which is attached a drag bar 56. Rotatably connected to the latter is a second yoke 58 which supports the cutting head 72 on horizontal pivots 75. The weight of the cutting blade 76, is partially supported by skids 80, 82. A chain 102 is connected between a point 104 on the rear of the subframe and an arcuate link 106, which is attached to one of a number of alternative points on the top of the cutting head, this chain passes through a helical spring 112 whose ends are hooked into the chain links. In use, this spring is under tension and thereby reduces the weight acting on the two skids, that on the inner skid being reduced by the vertical component of the force acting in the spring and that on the outer skid spring about the pivot 74. By adjusting the position of the spring ends on the chain and the position of the arcuate link on the cutting head, the required force acting upon the inner and outer skids respectively can be obtained.The cutting head is driven from a tractor power take off shaft via sheaves 88, 90, and a belt 91. A second chain 114, connects from the rear of the subframe, around a pulley attached to the top of the yoke 50, onto a lever 120 attached to the cutting head. A spring 127 is attached to this chain as shown to take up slack. Connected between a point at the front of the main frame and the yoke 58, is a pull bar 96, this embodies a release mechanism 100 which allows the pull bar to extend at a preset force. To bring the cutter to the raised position, the main frame is elevated by the tractor hitch causing the subframe to elevate more rapidly than the main frame. This in turn causes chain 114 to become taut giving rise to a torque on the cutting head about the axis 74, and resulting in the cutting blade and head rotating about this axis to the raised position. The cutter may then be folded over and locked into the transport position. When the cutting blade encounters an obstruction in use, the release mechanism 100 allows the pull bar to extend, the mower then pivots around axis 52, in so doing, the distance between sheaves 88 and 90 is reduced thereby easing the tension in the belt 91 and removing the drive from the cutting head. The mower can be returned to its operating position by raising the main frame causing the chain 114 to become taut, this pulls the mower forward and the release mechanism 100 renegages. The subframe is offset in the main frame such that by reversal, the device can be adjusted to work off tractors with either wide or narrow tread. For varying the angle of cut, a lever 64 secured to the drag bar 56 is adjustably connected to the yoke 58 by a screw 66.