Portable motorised pruning tool - comprises sickle blade reciprocated towards and away from operator by crank mechanism rotated by shaft in hollow bar

摘要

A portable motorised pruning tool partic. for the leafstalks of palm-oil trees, comprises a sickle blade (7) carried by two rods (6) slidingly reciprocated back and forth in cylindrical parts (5) of a casing (4). A crank mechanism is enclosed in the casing and driven by a rotating drive shaft housed in a hollow bar carrying a petrol engine (2). The frequency of reciprocation of the sickle blade is between 60 and 100 cycles per second. The cutting edge (7a) of the blade extends mostly perpendicular to the reciprocation direction. The crank mechanism includes a conical pinion on the drive shaft meshing with a conical gear fixed to a crankshaft, connecting rods linking the rods to the crankshaft. The centre of the cutting edge is on the axis of the bar, but the edge (7a) may be offset from the axis.