Abstract: A piston ring is assembled into a groove of a piston by pushing the piston ring out of a front end of a guide member. The piston ring is mounted on an outside of the guide member which has a diameter larger than an outside diameter of the piston. The pushing is carried out while maintaining a clearance which allows for the piston ring to undulate. This clearance is formed between a front end of the guide member and a plane including a groove surface which lies away from the front end of the guide member.

Abstract: An assembly station has plural roller assembling units mounted each aligned with one of the axes of the projections on a spider fitted to a shaft which is held in position at the station. A roller setting jig and an outer member assembling jig are alternately moveable to an assembly position at the station in line with an axis of the shaft. The roller setting jig includes a jig body vertically moveable along the axial direction of the shaft and a setting member on the jig body having holding portions for detachably holding the rollers to be assembled. The outer member assembling jig includes an outer member jig body vertically moveable along the axial direction of the shaft and a chuck member on the jig body for clamping the outer member.