The HSU sequence valve connects primary and secondary system branches after the pressure requirement in a third branch is satisfied.

Pressure must be connected to port 1 in order to operate the integral relief valve which pilots the sequence valve to connect ports 2 and 3. Port 1 pressure is ported thru orifices in the center of the valve to the pilor relief vale (in the upper portion of the body). Then this pressure exceeds the valve setting, pressure on the top side of the main spool is relieved. A pressure imbalance then exists across the main spool, allowing the flow between ports 2 and 3.

Several pressure ranges are available to choose from. The cartridge is constructed of steel parts, and all operating parts are hardened and ground as required. The cartridge is designed for easy service or field repair.