PISTON RETENTION APPARATUS AND METHOD

摘要

An apparatus and method for coupling a piston (18) to a rod (22) to form a cylinder assembly (10) are provided. The piston has a tapped bore (30) extending therethrough for coupling to a first threaded region (63) of the rod. The rod end (29) extends beyond the piston member (18) and includes a second threaded region (89) for coupling to a tapped bore (83) of a retaining member (26). The piston member is coupled to the rod member at a low torque, e.g., up to about 1000 Nm. A thread design of each of the threaded segment of the piston bore and the first threaded region of the first portion of the rod member may be formed with a root radius of greater than 0.125 pitch or with MJ class thread. The retaining member may include setscrews (96) offset from one another for frictional engagement with the rod end. The thread pitch between the rod and the piston may be coarser than between the rod and the retaining member. An interface and a seal region between the rod and the piston may be disposed closer to the rod end side (31) of the piston member than the threaded coupling (67).