Patent GB-676967-A (GB)
Title: Improvements in or relating to automatic engaging and disengaging arrangements for supported ploughs or other similar machines
IPC: A01B61/02
Filed: 1949-03-04
Abstract: 676,967. Plough couplings. CHAPRON, J. B. A. March 4, 1949 [April 30, 1948, Nov. 19, 1948], Nos. 5981/49 and 5982/49. Class 6(i) Relates to couplings for attaching ploughs or other agricultural machines to a tractor so that the machine is automatically disengaged on meeting an obstruction. The invention comprises a hook fast with either of the elements, i.e. the machine or the tractor, and bearing on a swing bar secured by pivoted arms to the other element. The hook 10, is in Fig. 2, pivoted in a spring-pressed strap 12 adapted to slide in a fixed slideway 13. The arms 16 of a plough are connected by a rocking-bar 17 sliding between plates 18, 19 secured to a cross-member 20 of the coupling frame which is mounted on the tractor. The hook 10 is lowered over the bar 17 and is held in place by a roller 21 rotatably mounted in a fork 22 connected to a cross-member 23. When the plough encounters an obstruction, the strap 12 slides and compresses the spring 14, thus releasing the hook from the roller. The hook then rocks on its pivot and releases the bar 17. The spring 14 can be adjusted to yield at a given resistance. To recouple the plough, the roller 21, Fig. 4, is removed by turning the roller-pin 24 through a half-turn so that a stud 25 on the end of the pin can enter a corresponding notch in the roller mounting. The plough is lifted by a winch on the tractor, the hoisting chain 47 engaging in a notch 48 in the hook 10, the chain being taken through a ring 50 on the tractor or the coupling frame and round a pulley 49 on the plough. With this arrangement, when the coupling hook rocks the chain is disengaged. The height of the coupling may be adjusted by a screw 31 turning in a bearing 32 connected to a fixed frame 35 of the tractor, the screw entering a nut 33 connected to the cross-member 23. Thus by turning the screw, the nut 33 is raised or lowered, the coupling being caused to turn about the pivot 34 of the member 23. In an alternative arrangement, Fig. 6, the hook 10 is pivoted to a member sliding in a guide 13 on the frame of the plough. The cross-member 20 secured to the hoisting links 28 of the tractor engages between the plates 18, 19, which are secured to the bar 17 of the plough. The hook is held by a detachable roller 21 turning in a fork 22 fastened to the upper guide plate. The plough is lifted by a hydraulic winch acting on the links 51, 52 to raise the links 28 which rock about a shaft 53. A chain 54 passing over a roller 55 on the upper frame 57 of the plough maintains the plough parallel to the ground during working. One end of the chain engages the hook 10 and is released when the coupling is disengaged and the other end is engaged in a fork 58 connected to the tractor through a spring 59. The level of the plough is arjusted by means of a nut 63. When the chain is used to hoist the plough directly, the end 65 of the chain, Figs. 8, 9, connected to the winch is secured to a pin 66 passing through the shaft 67 of the winch. The pin is grooved to engage a ball 70 acted on by a spring 71 bearing against a screw 72 in an axial hole in the shaft. By this arrangement when the tension on the chain is excessive the chain is automatically disengaged.