PURPOSE: To permit the replacement of a frictional part, application to the different kind of machines, and secure the automatic center adjusting function by constituting the top edge side part of a reciprocating movement member from a plurality of sleeve constitution members and fastening members and connecting the top edge side part with the basic edge side part in turnable ways.

CONSTITUTION: The top edge part 52 of a plunger 24 as reciprocating movement member is formed by arranging a sleeve root part 54, sleeve body 56 and a sleeve top part 58 in succession from a basic edge side part 50. The root part 54 and the body part 56 and further the body part 56 and the lop part 58 are jointed by the female and male parts 60 and 62 and further 64 and 66, respectively, and the root part 54 is fitted with a projection 68 in the basic edge side part 50. A fastening member 70 is installed, and a rod part 72 extending inside the body 56, screw part 74 which is formed at the both edges of the rod part 72 and is screwed with the projection 68, fitting part 76 fitted with the top part 58, and a welch plug 78 attached onto the edge surface of the top part 58 are formed onto the fastening member 70. Therefore, the screw part 74 is screwed with the projection 68, and the root part 54, body 56, and the top part 58 are fastened with the basic edge side part 50.