GB410320A - Improvements in portable pneumatic guillotine shears - Google Patents

Abstract

410,320. Guillotine shears for pruning and cutting hedges &c. FURSTOSS & LAGNIER, Rue du Commandant- Vidal, Cannes, France. May 25, 1933, No. 15161. Convention date, May 30,1932. [Class 6 (ii).] Portable pneumatic guillotine shears particularly for cutting or pruning trees and plants comprise a movable blade 1 actuated by at least one piston 11 movable in a cylinder 12 by gaseous pressure fluid. The blade 1 moves in slides on a counter blade 5 rigidly mounted on the frame and is in the form of a hook with a bevelled cutting edge 6. The blade 1 is connected to a piston rod 10. The cylinder 12 is formed with a platen 17 whereon moves a slide valve 16. By a series of ports 18, 19, 20 and conduits 21, 22, 23, pressure fluid from a pipe 26 may be delivered to the rear of the piston 11 or to the front of the piston for the return stroke. An auxiliary piston 13 may be provided on the rod 10 so as to move in a cylinder 15 connected to the conduit 23 so that fluid is conducted to the cylinder 15 for the return stroke. A port leading to the atmosphere may be provided at the top of the cylinder 12 ; the forward stroke is then effected rapidly. Alternatively, ports 27 may be provided in the wall of the cylinder so that a cushion of air at the top of the cylinder reduces the shock towards the end of the forward stroke. To prevent retardation of the piston on the return stroke, a valve 33 is provided in a conduit 32 leading to the atmosphere so that air may be supplied if a partial vacuum is set up in the top of the cylinder. The slide valve may be operated by hand for both strokes or it may be automatically operated by the piston for the return stroke. Shock at the end of the return stroke is avoided by the small cross-section of the piston 13 or by varying the cross-section of the port 20 by the slide-valve so as to control the fluid supplied to the cylinder 15, or by connecting the ports 18, 20 so as to use a portion of the compressed air operative during the forward stroke for the return movement. Shock at the end of the forward stroke may be reduced by resilient means such as springs. The blade 1 may be loosely connected to the rod 10, so that the latter acts as a hammer on the rear of the blade. Movement of the pistons may be controlled automatically by a device such as is used in pneumatic riveting machines.