A rail vehicle braking system with brakes that have at least one lining or at least one block, comprising: - a body (2; 102); - a braking linkage configured to act on at least one said brake that has at least one lining or at least one block; - a service brake (6; 106) comprising a braking piston (8; 108) which is movable relative to said body (2; 102) to act on said braking linkage and delimits with said body (2; 102) a service brake pressure chamber (13; 113) configured to be supplied by a first source of pneumatic pressure agent to put said braking piston (8; 108) into a service braking position; and - a parking brake (7; 107) configured to act on said braking piston (8; 108) of said service brake (6; 106) and having a working configuration and a resting configuration; said rail vehicle braking system being characterized in that said parking brake (7; 107) comprises: - a blocking device (20; 120) which is movable relative to said body (2; 102) to act on said braking piston (8; 108) and having a first position and a second position in which said blocking device (20; 120) is configured to immobilize said braking piston (8; 108) in service braking position, said parking brake (7; 107) then being in working configuration; - an actuating device (23, 24; 123, 124) which is movable relative to said body (2; 102) and having a locking position in which said actuating device (23, 24; 123, 124) is configured to hold said blocking device (20; 120) in its second position; said rail vehicle braking system being configured such that, when said actuating device (23, 24; 123, 124) is in its locking position, said service brake pressure chamber (13; 113) is supplied by a second source of pneumatic pressure agent of which the pressure value is determined, in order to apply, when said parking brake (7; 107) is in working configuration, a determined braking force; said rail vehicle braking system further comprising a control and actuation unit configured to: - receive an information item representing a value of said first source of pneumatic pressure agent; - process an information item representing a parking brake setting at least in its working configuration, for the purpose of actuating said movable actuating device (23, 24; 123, 124) at least in its locking position; and - determine a value of said second source of pneumatic pressure agent according to said parking brake setting and said information item representing a value of said first source of pneumatic pressure agent, for the purpose of supplying said service brake pressure chamber (13; 113). - a body (2; 102); - a braking linkage configured to act on at least one said brake that has at least one lining or at least one block; - a service brake (6; 106) comprising a braking piston (8; 108) which is movable relative to said body (2; 102) to act on said braking linkage and delimits with said body (2; 102) a service brake pressure chamber (13; 113) configured to be supplied by a first source of pneumatic pressure agent to put said braking piston (8; 108) into a service braking position; and - a parking brake (7; 107) configured to act on said braking piston (8; 108) of said service brake (6; 106) and having a working configuration and a resting configuration; - a blocking device (20; 120) which is movable relative to said body (2; 102) to act on said braking piston (8; 108) and having a first position and a second position in which said blocking device (20; 120) is configured to immobilize said braking piston (8; 108) in service braking position, said parking brake (7; 107) then being in working configuration; - an actuating device (23, 24; 123, 124) which is movable relative to said body (2; 102) and having a locking position in which said actuating device (23, 24; 123, 124) is configured to hold said blocking device (20; 120) in its second position; - receive an information item representing a value of said first source of pneumatic pressure agent; - process an information item representing a parking brake setting at least in its working configuration, for the purpose of actuating said movable actuating device (23, 24; 123, 124) at least in its locking position; and - determine a value of said second source of pneumatic pressure agent according to said parking brake setting and said information item representing a value of said first source of pneumatic pressure agent, for the purpose of supplying said service brake pressure chamber (13; 113).