PNEUMATIC AETUATION WITH HYDRAULIC DAMPING FOR WORKING PART OF DRILL TRAVEL

摘要

Operating means comprise an air cylinder and a hydraulic cylinder mounted in axial alignment. A rod passes through both cylinders, and a piston in the air cylinder is mounted on the rod. A hollow member which is positioned about the rod passes through the hydraulic cylinder and extends from the ends thereof, and a piston in the hydraulic cylinder is mounted on the hollow member and divides the interior of the hydraulic cylinder into first and second chambers. First and second axially adjustable engagement members are mounted on the rod to engage the ends of the hollow member upon movement of the rod in opposite respective directions, whereby movement of the piston in the air cylinder is accompanied by movement of the piston in the hydraulic cylinder. The first and second chambers of the hydraulic cylinder are connected by first and second passageways, each of which is provided with a non-return valve and a flow rate controlling valve. The non-return valves are biased in opposite respective senses. Thus, movement of the piston in the hydraulic cylinder is controlled in both directions, by the flow rate controlling valves respectively.