Braking system for the wheel axles of a trailer

Braking system for the axles (3a) of wheels (3) of a trailer connected to the hydraulic circuit (4) of a traction unit, comprising a disc (2) for each wheel (3) mounted on the axle (3a) and a floating caliper (1) with hydraulic control means (205;221a,204;211) for each disc (2) comprising a first movable jaw (101) which carries a respective friction pad (101a) and a second movable jaw (102) which carries a respective friction pad (102a), symmetrically arranged on opposite sides of the disc (2), said floating caliper comprising means (200,223,221,222a,222,111) for automatically performing parking braking, which can be deactivated by the hydraulic circuit (4) of the traction unit, and means (100,112,222,111,211) for performing service braking, which are hydraulically connected to a second control circuit (542,541,544,501) of a pressure booster device (500) provided with a first control circuit (511,512,515) supplied by the fluid of the hydraulic circuit of the traction unit and interacting with said second control circuit supplied by an auxiliary reservoir (501) containing a second fluid independent of that of the traction unit.