This valve is a spring biased closed, pilot-to-close check cartridge that has a 1.8:1 pilot ratio. The valve allows flow from port 1 to port 2 and blocks reverse flow. Pressure at the pilot port opposes pressure at port 1 at a ratio of 1.8:1. This valve is most often used in regeneration circuits.

• Minimum clearances between the spool and sleeve and a seal on the pilot piston diameter significantly reduce the potential for silting.
• Nominal pilot ratio is 1.8:1. This means that a pressure of 1000 psi (70 bar) at the pilot port will close a valve against a pressure of 1800 psi (125 bar) at port 1. Any decay or loss of pilot pressure could allow the valve to open, even if it is a momentary decay or loss.
• Pressure at the port 2 area directly opposes pilot pressure.
• Reverse flow through the valve from port 2 to port 1 is not possible under any condition.
• With equal pressures at all ports the valve is closed.