| 摘要 |
<p>Disclosed is a shock absorber or damping device for a pivoting chainsaw on a tree harvester that operates at the end of the return cycle for a rapid withdrawal. The harvester head has an actuator for feeding-out and returning a pivotal saw assembly in a harvester. The harvester head comprises a shock absorber for absorbing an impact upon an arrival of the saw assembly at a home position at an end of a return stroke of the saw assembly. The mechanical shock absorber, in order to permit a fast return stroke of the saw assembly, is inactive during most of the return stroke and is active substantially at the end of the return stroke only, and is included in the actuator. The actuator includes a member that is axially movable between two end positions, one of which corresponds to a completely returned saw assembly, and the axially movable member has one end engaging a pivotal member for the feeding-out and the returning of the pivotal saw assembly. The pivotal member is a toothed rotary wheel and the axially movable member is a piston rod having one end shaped as a rack for cooperation with the toothed wheel for the feeding-out and the returning of the pivotal saw assembly. The shock absorber comprises a spring holder mounted in an axial bore in the piston rod, the spring holder having a head and a shank, the head projecting axially from an axial end surface of the piston rod, the shank being surrounded by at least one compression spring compressed between the head and a bottom of the axial bore.</p> |
