1 . A rail vehicle braking system with brakes that have at least one lining or at least one block ( 5 ), comprising: a body ( 2 ; 102 ; 202 ; 302 ; 402 ); a braking linkage ( 4 ) configured to act on at least one said brake that has at least one lining or at least one block ( 5 ); a service brake ( 6 ) comprising a braking piston ( 8 ; 108 ; 408 ) which is movable relative to said body to act on said braking linkage ( 4 ) and delimits with said body a service brake pressure chamber ( 13 ; 113 ; 413 ) configured to be supplied by a first source of pneumatic pressure agent ( 50 , 51 , 53 ) to put said braking piston into a service braking position; and a parking brake ( 7 ) configured to act on said braking piston of said service brake and having a working configuration and a resting configuration, wherein, said braking piston is disposed in said body and has two sides, respectively a first side ( 17 ; 117 ) configured to act on said braking linkage ( 4 ) and a second side ( 18 ; 118 ) which is an opposite side to said first side and which is turned towards said service brake pressure chamber, said service brake further comprises a piston rod ( 21 ; 121 ; 221 ; 321 ; 421 ) disposed in said service brake pressure chamber and attached to said second side of said braking piston, said parking brake is disposed in said body and comprises a blocking device ( 20 ; 120 ; 220 ; 320 ; 420 ) disposed in said service brake pressure chamber, which device is movable relative to said body to act on said piston rod and having a first position and a second position, as well as an actuating device ( 23 , 24 ; 123 , 124 , 180 ; 223 , 280 ; 323 , 380 ; 423 , 424 ) which is movable relative to said body, configured to be electrically actuated and having a stable position, and said blocking device and said actuating device is configured such that: with said braking piston in the service braking position and said parking brake is in working configuration, said actuating device acts on said blocking device until the latter immobilizes said piston rod so as to block said braking piston in the service braking position, said blocking device then being in the second position and said actuating device in the stable position, and with said parking brake in resting configuration, said actuating device acts on said blocking device until the latter frees said piston rod so as to unblock said braking piston from the service braking position, said blocking device thus being in the first position, whereby the braking force applied to said braking linkage when said parking brake is in working configuration is directly related to the braking force applied to said braking linkage by said service brake in the service braking position, independently of the force applied by said blocking device on said piston rod.
2 . The system according to claim 1 , wherein said actuating device is formed by an electrical actuator.
3 . The system according to claim 1 , wherein said blocking device ( 120 ; 220 ; 320 ; 420 ) is disposed in a cavity ( 134 ; 234 ; 334 ; 434 ) of said body ( 102 ; 202 ; 302 ; 402 ).
4 . The system according to claim 1 , wherein said blocking device is formed by a blocking finger ( 20 ; 120 ; 220 ; 320 ; 420 ) and said actuating device is formed by an electrical actuator movable relative to said body and by a spring member ( 24 ; 124 , 180 ; 280 ; 380 ; 424 ); said electrical actuator being configured to hold said blocking finger in the first position when said electrical actuator is electrically supplied, in which first position said blocking finger is away from said piston rod; said spring member being configured to hold said blocking finger in the second position when said electrical actuator is not electrically supplied, in which second position said blocking finger immobilizes said piston rod.
5 . The system according to claim 1 , wherein said blocking device is formed by a blocking finger ( 20 ; 120 ; 220 ; 320 ; 420 ) and said actuating device is formed by an electrical actuator movable relative to said body; said electrical actuator being configured to hold said blocking finger in the first position when said electrical actuator is electrically supplied, in which first position said blocking finger is away from said piston rod; said electrical actuator being further configured to hold said blocking finger in the second position when said electrical actuator is not electrically supplied, in which second position said blocking finger immobilizes said piston rod.
6 . The system according to claim 4 , wherein said spring member ( 180 ; 280 ; 380 ) is disposed in a cavity ( 134 ; 234 ; 334 ) of said body ( 102 ; 202 ; 302 ).
7 . The system according to claim 1 , wherein said parking brake further comprises an intermediate actuating lever ( 147 ; 247 ) attached both to said blocking device ( 120 ; 220 ) and to said actuating device ( 123 ; 223 ) and configured to actuate said blocking device in response to the movement of said actuating device.
8 . The system according to claim 1 , wherein said blocking device ( 20 ; 120 ; 220 ) has at a distal end a tooth having at least one inclined edge ( 175 ; 275 ) and configured to cooperate in complementary manner with a complementary teeth formation having at least one inclined edge ( 76 ; 176 ; 276 ; 476 ) of said piston rod ( 21 ; 221 ) or of an intermediate part ( 146 ; 446 ) disposed between said piston rod ( 21 ; 221 ) and said blocking device ( 20 ; 120 ; 220 ).
9 . The system according to claim 1 , wherein said blocking device ( 320 ) has at a distal end a tooth having straight edges ( 375 ) and configured to cooperate in complementary manner with a complementary teeth formation having straight edges ( 376 ) of said piston rod or of an intermediate part ( 346 ) disposed between said piston rod and said blocking device ( 320 ).
10 . The system according to claim 1 , wherein said service brake further comprises a ratchet wheel ( 146 ; 246 ; 346 ; 446 ) mounted on said piston rod ( 121 ; 421 ) and configured to mesh with said blocking device ( 120 ; 220 ; 320 ; 420 ) when the latter is in the second position, in order to immobilize said piston rod.
11 . The system according to claim 1 , wherein said parking brake ( 7 ) further comprises a unlocking part ( 29 ; 429 ) for unlocking said parking brake when the latter is in working configuration, which unlocking part is configured to act on said blocking device ( 20 ; 420 ).
12 . The system according to claim 11 , wherein said unlocking part is configured to be electrically actuated.
