PNEUMATIC SPRING COUNTERBALANCE HAVING IMPROVED DAMPING STRUCTURE

摘要

PNEUMATIC SPRING COUNTERBALANCE HAVING IMPROVED DAMPING STRUCTURE A pnemumatic spring counterbalance extensible link including a closed end cylinder with end end connector a piston and rod assembly within the cylinder and maintained therein by the crimped over end portion of the cylinder retaining a rod bushing and rod to cylinder seal assembly. The cylinder is pressurized preferrably prior to assembly of the bushing and seal assembly into the cylinder. The piston assembly includes an effective check valve and orifice by-pass structure for metered gas flow past the piston in one direction and free flow past the piston in the other direction of piston movement. A small predetermined amount of oil is contained in the cylinder and provides lubrication for the seals and piston and provides a damping effect at the end of the extension stroke. A standpipe sleeve is secured on the piston extending toward the seal assembly around the piston rod and controls disposition of the oil to assure damping at the end of the extension stroke. A piston and piston ring structure enhance reliability of control of the oil flow, by providing a peripheral piston to cylinder seal and assures that fluid only passes across the piston via the check valve and orifice by-pass structure in the piston.