Abstract: An oil system is provided for a brake disk whose brake linings are provided with generally radial grooves through which oil flows from the radially inner portion of the disk to the radially outer portion of the disk. An oil collection channel is located radially outside of the brake linings and collects oil expelled from the brake linings for return through at least one return passage to the oil supply. The return passage is small enough to throttle the flow of oil when the brake is operating at high rotational speeds, but large enough to allow unhampered oil flow at low rotational speeds. This produces a back pressure in the oil collection channel at high rotational speeds, and to a lesser extent, in the grooves in the brake lining. This, in turn, improves lubrication of the brake linings at high speeds.