1. Most applications where pressure compensated proportional valves are used involve metering out of the actuator down stream of the counterbalance valve. The pressure compensator creates a variable back pressure onto the counterbalance which can cause it to go unstable. It is basically the counterbalance valve and the compensator interacting with each other. This problem can normally be overcome by using a vented counterbalance valve (CW** type) where the pilot spring chamber is drained separately from the outlet port. Ideally a four port valve should be used with the drain port going separately back to tank, but if this is not practical then there is a three port version available where the spring chamber is vented to atmosphere (CA** type). The vent port is in the hexagon of the cartridge so there is a possibility of a leakage over a period of time.
2. When a counterbalance valve is required on the rod side of a regenerative circuit, the outlet port of the valve is connected to the full bore side of the cylinder where the external pilot is coming from. This means that both sides of the pilot piston are subjected to the same pressure when the cylinder is selected to extend and the valve will stay closed due to the spring force. The only way this system can work is if a vented counterbalance valve (CW** type) is used where the pilot spring chamber is drained separately back to tank. Again it is preferable to use a four port valve but if necessary a 3 port vent to atmosphere valve (CA** type) can be used.