Cross-port relief valves (also known as braking valves) are typically used to limit maximum motor torque and to provide the system overpressure protection.

If the directional valve that directs flow to the motor and the attached flywheel mass is closed suddenly, the motor, which has become a pump, will have no supply of oil at the inlet and no outlet flow path. Cross-port relief valves solve this problem and prevent motor cavitation damage, burst hoses and snapped or twisted motor shafts.

It is basically made up of two relief valves that, when opened, will send flow across to the other side of the motor circuit.