Braking system for braking a rotor relative to a stator

A hydraulic motor comprising a rotary cylinder block having radial pistons and disposed in a stationary casing having a reaction member for the pistons, said hydraulic motor having a rotor and a stator which are constrained to rotate respectively with the cylinder block and with the casing of said motor, the latter having a braking system comprising brake disks disposed in a disk enclosure, which disks are distributed in a first series of disks secured to the stator and in a second series of disks constrained to rotate with the rotor relative to the stator, the system further comprising a brake piston device that can be caused to go between a braking configuration in which an active portion of said piston device co-operates with the brake disks so as to urge said disks into braking contact, and a brake release configuration, the system further comprising control means for controlling the piston device, which control means comprise braking resilient return means continuously urging the brake piston device towards its braking configuration, a brake release chamber distinct from the disk enclosure and suitable for being fed with pressurized fluid via a brake release duct so as to urge the brake piston device into its brake release configuration, and a braking chamber suitable for being fed with pressurized fluid so as to urge the brake piston device towards its braking configuration, the braking system further comprising a cooling device for cooling the brake disks by means of fluid flow, wherein, for the purpose of being fed with cooling fluid, the cooling device is provided with a cooling duct branching from the brake release duct and communicating with the disk enclosure, said cooling duct being formed in a casing portion of the braking system, and wherein the system is provided with means for limiting the quantity of cooling fluid tapped by the cooling duct from the brake release duct.