Excavator with tool on endless track - has rams with grips engaging components on tool to drive it

摘要

The excavator has a tool running round an endless track about one or more axes under the action of drive. The latter comprises two or more rams (20), connected by first valves to a supply for a medium under pressure. This delivers fuel to the rams at one side of the piston so as to perform a working stroke from the initial position. Second valves on the same side of the piston connect this to a discharge, the piston being returned to the starting position after the working stroke. The sets of valves are operated so that one is always shut while the other is open. At the free end of each piston rod is a grip (26), engaging with one of a set of mating components (24) at regular intervals along the tool near the outer periphery.