The 9A control controls displacement in proportion to an electric current between zero and 350 milliamps for the 24 volt version, and up to 650 milliamps for the 12 volt version. The control signal is a Pulse Width Modulated signal. Current signal to one coil drives the pump in one direction, and to the other coil in the opposite. Adjustable maximum displacement stops are included. The 9C option, with automatic brake control, is also available
The 7 control is a high response displacement control that uses a servovalve to direct high flow levels to and from the vane chambers, in order to achieve high stroke rates on the pump. A feedback potentiometer or RVDT (Rotary Variable Differential Transformer) is used to feed back the rocker cam position to the controlling electronics to achieve stable operation. The 7D6 control uses a servovalve and a feedback potentiometer for feedback, the 7D8 uses an RVDT. The 7F6 control uses servovalve and a the feedback potentiometer, but also has a special valve block with a valve in it to shut off the servovalve, so that control may be taken over by a 4A2 control also mounted to the pump as a manual override. The 7F8 is the same, except using an RVDT
