Andreas Stihl

Manfred Fischer

Werner Hartmann

Wilfried Linke

Klaus Dussler

For motor-driven chain saws, there is the danger that the chain saw will be kicked back if the reaction forces suddenly increase intensely in response to the forward thrust. This kickback effect and the danger of accident associated therewith are intended to be reduced by means of a special configuration of the saw chain. The saw chain has drive links which have an approximately triangular shape and which engage the tooth gaps of the nose sprocket with inclined flanks. The drive links are configured to be asymmetrical with respect to a partition line running between the two pivot axes of the link so that the forward flank angle is greater than the rearward flank angle referred to the partition line. The two flank angles together are greater than the opening angle of the V-shaped tooth gap of the nose sprocket. The saw chain can be configured as a low-profile chain with the spacing between the pivot axes of the cutting link being at least 10% greater than the spacing of the cutting edge to the plane containing the connecting line between the two pivot axes of the cutting link. Furthermore, the depth limiter can have an area in its upper region which is at least 4 mm.sup.2.

Motor-driven chain saw with a sprocket guide

With motor-driven chain saws, there is the danger that the chain saw will be thrown upwardly and rearwardly when it is applied to wood by the user with a forward thrust. Serious injuries can then occur. The invention is directed to a motor-driven chain saw which is so configured that the cutting forces are automatically reduced in response to the occurrence of excessive reaction forces so that the reaction force is immediately reduced to a tolerable amount thereby eliminating the kickback effect. The drive links engaging the nose sprocket of the guide bar are so dimensioned that they can further pivot in the tooth gaps of the nose sprocket out of their normal position and, in this way, take the cutting links with them in such a manner that the free angle of the cutting teeth is reduced. The drive links are latched in the pivoted-in position on the nose sprocket in order to assure that the cutting links will retain the position with the reduced free angle over the entire turnaround region of the guide bar. For this purpose, latches are provided on the drive links and/or on the nose sprocket.

Motor-driven chain saw having an anti-kickback sprocket

With motor-driven chain saws, there is the danger that the chain saw will be thrown upwardly and rearwardly when it is applied to wood by the user with a forward thrust. Serious injuries can then occur. The invention is directed to a saw chain which is so configured that the cutting forces are automatically reduced in response to the occurrence of excessive reaction forces so that the reaction force is immediately reduced to a tolerable amount thereby eliminating the kickback effect. The drive links of the saw chain which engage into the nose sprocket of the guide bar are so dimensioned that they can further pivot in the tooth gaps of the nose sprocket out of their normal position and, in this way, take the cutting links with them in such a manner that the free angle .alpha. of the cutting teeth is reduced.

Growing community of inventors

Asperg, Germany

Manfred Fischer