Cartridge Valve Cover
Function N - Basic PC - Pilot operated check
The standard directional cover (model code letter N), contains a pilot pressure passage with an orifice to control the poppet’s opening and closing rate. When used with insert model D15 (1:1.5 area ratio poppet), or model D20 (1:2 area ratio poppet), the combined cover and insert, Figure 9, becomes a check valve. Port X in the cover is connected to port B in the insert. This allows free flow from insert port A to port B while blocking flow from B to A.
Using a model N cover with a D15 insert, can provide directional control of flow from insert port A to B or from B to A. Pressurizing port X from a remote source will block flow from insert port A and B. With X connected to B, system flow is from A to B. Flow will be from B to A if X is connected to tank or A.
A model N cover is used with a D105 insert (1:1.05 area ratio) which can be supplied with an orifice in the poppet. This configuration is used to open A to B or block A to B. D105 poppets cannot be used for flow from B to A. The orifice avoids the need to machine a connecting hole in the manifold to port A. To obtain a D105 insert with an orifice in the poppet (i.e. D105V), the orifice size must be specified at the end of the insert model number.
Damping can be achieved with a model R15 insert (area ratio 1:1.5) and R20 (area ratio 1:2), see Figure 14. The poppet has a skirt with a damping notch which helps smooth shifting (reduces gain) of the poppet. R15/R20 inserts may be used with any check or directional function where a D15/D20 insert is ordinarily used.