An emergency brake. The emergency brake includes a pack of disks and counter-disks. A resilient actuator acts on the pack to push the disks and counter-disks into a braking condition. A piston acts on the pack in opposition to the resilient actuator in order to disable braking. A hydraulic circuit has a pressurized hydraulic fluid controlling the piston, which can be activated to actuate the piston in a condition releasing braking of the pack. The hydraulic circuit also has a branch delivering actuator fluid to the braking pack to lubricate and cool the braking pack when the circuit is deactivated.