GB961137A - Improvements in or relating to power operated hedge and like trimmers - Google Patents

Abstract

961,137. Hedge-cutters. E. V. TWOSE (MANUFACTURING) Ltd. June 29, 1960 [June 29, 1959], No. 22270/59. Heading A1E. Relates to a power-operated hedgetrimmer of the kind having a reciprocating cutter-bar 15 pivoted to the outer end of a jib 13 itself pivoted at its inner end to an attachment member 1 on the side of a tractor 2 having a hydraulic fluid-pressure supply-source and a mechanical power takeoff 53, so that the jib may pivot about a horizontal axis, there being means 16 for raising and lowering the jib about its axis and means 19 for angularly adjusting the cutter-bar about its pivot on the jib. According to the invention, the last-mentioned means is a double-acting hydraulically-operated device which is so arranged that it also maintains the angular relationship between the cutter-bar 15 and the attachment-member 1 when the jib is adjusted relatively to the attachment-member. The member 1 comprises a tube journalled in bearings 4, 9 carried by standards 5, 10 secured fore and aft on the tractor so that the tube extends horizontally at the height of the rear-wheel rims. The tube carries a vertical pivot-bearing 28 for the jib 13 and universal-joints for a doubleacting hydraulic jack 19 and for a telescopic strut 29. The jib is raised and lowered by a single-acting hydraulic jack 16 connected between a universal joint on a member 17 fixed to the tractor-chassis and a fixed pivot on the jib. The cutter-bar is pivoted on a driven shaft 61 rotating on the end of the jib 13 and carrying the drive to the cutter through a crank-disc 62; the drive is derived from a belt 54 on the power take-off 53 and continues via a shaft 51 within the tube 1 to a belt-drive 60 connected to the shaft 61 through a pulley 58. A sprocket 20, integral with the mounting- shoe 14 for the cutter 15, is free on the shaft 61 and is entrained by a chain 18 forming a closed loop around the sprocket 20 and an idler 21 on the jib. The loop includes a member 25 slidable along a guideway 27, the outer end of the jack 19 being secured to the member 25 so that extension or retraction of the jack will tilt the cutter-bar about the shaft 61, or, conversely, non-movement of the jack 19 will maintain the attitude of the cutter-bar constant when the jib is adjusted by the jack 16. The telescopic strut 29 includes a rod 30 encircled by a part 33 having limited spring-loaded lost-motion and including a shear-pin 41 which permits complete collapse of the strut under excessive stress, the various universal joints and the vertical pivot 28 permitting corresponding movement of the jib. Further protection against torsional distortion is provided by a shearpin 48 connecting two flanges 45, 46 on the inner end of the jib, the two flanges being pivoted together by a bolt 47. The hydraulic circuits may also incorporate pressure-relief valves.