Furuno PUMPHRP10-12 Pump for Navpilot 500 & 511 - 1.7ci/second @12 or 24 VDC ( for ram sizes up to 14 cubic inches) The PUMPHRP10-12 is a reversing pumpset designed to interface the NavPilot 500 Autopilot with a hydraulic steering system. The pump assembly incorporates a reversible gerotor gear pump, a two-piece gear housed in an eccentric ring. This allows for incredibly quiet, reliable and precise operation. A hydraulic steering system consists of a hydraulic actuator and one or more steering wheel pumps, or helm pumps. As the steering wheel (helm pump) is turned in the port direction, hydraulic oil is pumped into the port hydraulic steering line. This oil is directed into the port side of the steering cylinder. As the cylinder moves to port, oil from the starboard side of the cylinder returns to the helm pump through the starboard hydraulic lines. One end of the cylinder is fixed and the other is connected to a tiller arm, which is connected to a rudder shaft. With this connection to the tiller arm the linear movement of the cylinder to port is changed to rotary movement, which turns the rudder and steers the vessel to port. Moving the steering wheel to starboard produces the same reaction with oil being pumped out of the starboard line and returning through the port line. If more than one helm pump is used, a return/fill line must be installed to connect the cases of all helm pumps together. The output flow rate of the pumpset determines the speed of the steering cylinder. The PUMPHRP10-12 outputs 1 cu. in. of oil per second and requires a 12VDC input.