GB970824A - Saw chain - Google Patents

Abstract

970,824. Sawing. McCULLOCH CORPORATION. July 2, 1962 [April 20, 1962], No. 25287/62. Heading B5L. A saw chain comprises side links 10 and centre links 11 alternately connected by hinge means 12 disposed on transverse axes, centre cutter elements 29 for cutting a central portion of a kerf in material to be sawn extending vertically outward from selected links, the elements each having a blade portion having a forward transverse cutting edge, side cutter elements 30, 30<SP>1</SP> for widening the kerf portion cut by the centre cutter elements and positioned on opposite sides of the chain on selected links, each element having a blade portion which extends laterally outwardly on its side of the chain and a transverse cutting edge, and depth gauges 36, 36<SP>1</SP> extending outwardly from selected links, the gauges and cutter elements having their outer surfaces lying on arcs 54 of equal radii, the centres of the arcs being correspondingly centrally positioned relative to the hinge axes of the selected links. The centre links have downwardly extending tangs 13 which travel in a groove in a saw bar and engage pockets formed between the teeth of a driving sprocket and a pair of discs one on each side of the sprocket. The centre and side links have extensions 17 forming surfaces 18 for engaging the outer surfaces of the sprocket teeth and the outer surfaces of the discs, respectively, and the side links have curved surfaces 20 for engaging the discs so that the vertical movements of the links are limited and the cutting elements and depth gauges positioned for sharpening by a whetting member in the chain saw engine. The links are assembled in the chain in two sequences. In the first sequence, a centre link 11a has a centre cutter element 29 and is followed by a side link 10a having a right-hand side cutting element 30 and a depth gauge 36. A centre link 11b follows the side link 10a and has a right-hand offset cutting element 38, and this is followed by a side link 10b having a left-hand side cutting element 30<SP>1</SP> and a depth gauge 36<SP>1</SP>. The first sequence is completed by a centre link 11c having a left-hand offset cutting element 38<SP>1</SP> and a side link 10b having a right-hand cutting element 30. The second sequence comprises links and cutting elements in the following order: a centre link having a centre cutting element, a side link having a left-hand side cutting element and a depth gauge, a side link having a left-hand offset cutting element, a side link having a right-hand side cutting element, a centre link having a right-hand offset cutting element, and a side link having a lefthand cutting element. The greatest cutting load is taken by the centre links and cutting elements and these are thicker than the side links. In an alternative embodiment, the tangs 13 may be on the side links and arranged to straddle a bar.