GB645913A - Improvements in hedge cutters - Google Patents

Abstract

645,913. Hedge-cutters. HODGKINSON, J, and ROBERTS, H. May 27, 1948, No. 14298. [Class 6(ii)] Relates to hedge-cutters in which a relative movement takes place between a first blade having a plurality of teeth each with a cutting edge, and a second blade having abutment cutting edges cooperating with the teeth of the first blade. The invention consists in arranging one blade to move relatively to the second blade so that it always moves parallel to itself and each point on it describes periodically a closed curve. Attached to a tractor 11 is a frame 12 supporting a tube 13 housing a shaft 14 connected by a universal joint to a shaft 15 driven by the tractor through a pulley 16, belt 17 and shaft 18. The tube is partly supported by a wire rope 22 passing over a pulley 23 to a drum 24 rotated by a handle 25 connected to the drum by a ratchet. The tube 13 is attached to a gear-box cover 26, Fig. 3, which has two lugs 26a carrying a pin 27 on which swings a strut 28 pivotally connected to the rear of the tractor. A hand-lever with a locking arrangement, such as a quadrant anchorage, is connected to one end of a link bar (not shown). The other end of this bar is pivotally connected to a bellcrank lever 29 having an arm pivotally connected to a link-bar 30 which is connected to a radius bar 31 and a link bar 32, Fig. 1. The radius bar is also connected to a lug on the tube 13. On a pin 33, Fig. 3, extending through the gear-box cover, swings a gear-box casing 34 attached to a fixed cutter blade 35. The link bar 32, Fig. 1, is connected to a lug on the blade, so that by movement of the hand lever the inclination of the blade 35 relative to the tube 13 may be adjusted. The shaft 14, Fig. 3, carries a pinion 36 meshing with a pinion 37 at one end of a rotatable sleeve 38. At the other end of the sleeve is a pinion 39 meshing with a pinion 40 on a shaft 41 journalled in the casing. This shaft 41 carries a circular eccentric 42 engaging a circular aperture in a lug 44a of a moving blade 44 and a second eccentric 43 engaged in a connecting rod 48, Fig. 2. The blade 44 has a second lug 44b engaging a circular eccentric 45 mounted for rotation on a spindle 47 anchored in a lug 35a on the fixed blade. This spindle also carries an eccentric 46 engaging the connecting rod 48, the phase angle between the eccentrics 42 and 43 being the same as between the eccentrics 45 and 46. The fixed blade 35 has cutting teeth 35c concave in the direction of the cutting stroke and the moving blade has abutment edges 44c concave in the opposite direction. In a modification the drive from the shaft is transmitted to an eccentric in the moving blade through a sprocket which drives a second sprocket by means of an endless chain. The second sprocket drives a second eccentric engaging the moving blade.