Patent ID: 7197874

Claim:
A tandem master cylinder (TMC, 1 ) comprising a housing ( 2 ) with a main bore which is open on one end, a first pressure chamber ( 21 ), an inner piston ( 6 ) that is linearly slidable in the housing to displace pressure medium out of the first pressure chamber ( 21 ), a second pressure chamber ( 22 ), an outer piston ( 7 ) that is linearly slidable in the housing to displace pressure medium out of the second pressure chamber ( 22 ), the inner piston ( 6 ) being acted upon by the pressure of the first pressure chamber ( 21 ) on one end and on the opposite end by the pressure of the second pressure chamber ( 22 ), and the outer piston ( 7 ) being acted upon by the pressure of the second pressure chamber ( 22 ) on one end and exposed to the outside atmosphere on the other end, and a compression spring ( 12 ) arranged between the two pistons ( 6 , 7 ) and coupled to the outer piston ( 7 ) by means of a retainer ( 13 ) allowing a limited expansion of the compression spring ( 12 ) toward the inner piston ( 6 ), wherein the housing ( 2 ) comprises a closable radial opening ( 26 ) and wherein the retainer ( 12 ) comprises a receiving portion ( 19 , 20 ) which radial opening ( 26 ) and receiving portion ( 19 , 20 ) are arranged with respect to each other so that a locking member ( 23 ) can be inserted through the radial opening ( 26 ) into the receiving portion ( 19 , 20 ).