On-board centralized system tor regulating the pressure of the tyres of a motor-vehicle

An on-board centralized system for regulating the pressure of the tyres of a motor-vehicle. Tue system comprises a source of pressurized air (lOl), two toroidal pneumatic rotary joints (T) each associated to a driving wheel (W) ofthe motor-vehicle, and a circuit that sets in communication the source of pressurized air (I O l) with an inlet fitting of each pneumatic rotary joint (T). Tue output member of the constant-velocity joint (J) and the wheel spindle (7) have an internal duct (65) for passage of air, connected on one side to the respective pneumatic rotary joint (T) and on the other side to a plenum (P) of the respective driving wheel (W). Each non-driving wheel (WR) has its wheel spindle ( 46) traversed by an axial bare for the passage of air, connected on one side to the air-supply circuit via a pneumatic rotary joint (TR) and on the other side to a plenum (PR) of the non-driving wheel (WR), which is in turn connected to the inner chamber (C) of the tyre. Each driving wheel or non-driving wheel has its plenum (P, PR) connected to the inner chamber (C) of the tyre via two parallel lines (L2, L3), for deflating and inflating, respectively, the tyre interposed in which are respective one-way valves (28, 32). Tue one-way valve (28) on the deflation line is provided with a return spring (30), which guarantees a pre-set minimum value of he pressure of the inner chamber (C) of the tyre.