A valve for controlling fluid flow in a fluid system is disclosed. The valve includes a housing, a servo spool, and a piston. The servo spool defines a spiral groove and a spiral land. The piston defines an orifice configured to provide flow communication to a supply of pressurized fluid and an orifice configured to provide flow communication to a portion of the fluid system exterior to the valve. The valve further includes a main spool operably coupled to the piston. The main spool is configured to control flow of fluid in the fluid system. The spiral groove and spiral land are configured such that angular displacement of the servo spool results in a force imbalance on the piston, thereby moving the piston and the main spool in one of a first direction and a second direction.