(8) (8) Brake piston Brake piston Lubricate specified hydraulic oil on outer sliding face of piston (28) and assemble brake piston to housing (1). It is too tight to assemble piston (10) because O-rings (14,29) are fitted, there- fore it is recommended to push piston (28) horizontally by hands at once. (9) (9) Spring Spring (30, brake unit) Assemble spring (30) to piston (28) of brake unit. Insert spring (30) into original position. (10) Lubricate locating pin for antirotation of valve plate (16) of cover (12) with grease sufficiently and install locating pin to hous- ing. (11) (11) Balance plate Balance plate Assemble valve plate (16) to cover (12). Be cautious of assembling direction. 7-18