The purpose of a high pressure carry over (HPCO) is to allow pressure to be transferred from one valve to another in a hydraulic system:
HPCO, also known as “power beyond”, is a feature of a hydraulic directional control valve that separates the pressure gallery from the tank gallery. This allows the pressure to be carried over to another valve, usually another directional control valve.
To use HPCO, the tank ports of both valves must be connected to the tank. The capacity of the valves should also be able to handle the flow from the hydraulic pump.
HPCO can be used when you want to control a function with a valve from another part of the machine. For example, you can use HPCO to carry pressure from the first valve to the P port of the second valve when the first valve is not in use.
To prevent damage to the outlet and return ducts in the spool valve as well as the slide seals of the control valve. It also prevents back pressure on exhaust and return passage of the control valve and other system components.
The HPCO may be installed in different ports depending on the manufacture however the valve will mostly have a separate port for the HPCO that is different to the tank port. In case of the Badestnost valve the HPCO is to be installed in the N port. The tank port will still need to be connected on any brand of valve.