Linear hydrostatic drive controllers are available with rated bipolar output currents from 25 to 200 ma. They may be operated both open or closed loop with a suitable feedback transducer. Open loop regulation is typically better than 1%, using the internal current feedback. Proportional or integral gain mode operation is standard. The input and feedback command signals can be obtained either from the included reference power supply with a potentiometer or an external voltage source. The controllers also include a scale circuit that may be used for high voltage or 4 to 20 ma. current signals. For high performance applications, provisions are included for an external dither signal, or optionally, an internal dither generator. Models are available with or without variable, linear acceleration and deceleration ramps. All models include bias, gain and current limit adjustment controls. All of the internal controls are multiturn devices.

These industrial controllers contain a transformer and power supply, accordingly they can be powered directly from a 115 or 230 volt ac line. Line voltage selection jumpers are included. Models are also available for operation from a bipolar 18 to 30 volt dc power source. To simplify installation, the circuit board is designed to replace the subplate in a standard NEMA enclosure.

The model series D2653 is unique in that it has two outputs that are designed to adjust the displacement controller for both the pump and the motor on hydrostatic transmissions. A phase adjustment control allows the pump and motor displacements to be varied in parallel or in series. Parallel operation will stroke the units at the same time while series operation will stroke the pump to maximum displacement and then stroke the motor to minimum displacement. The pump displacement output will follow the polarity of the input signal, thus allowing bidirectional operation by stroking the pump through it's center position. The output for the motor is always unidirectional. Optionally, the motor output signal can be supplied as a voltage that may be used to drive a high current proportional solenoid valve via a suitable amplifier.

Although, specifically designed for electrical displacement controllers, these devices are also suitable for use with all servovalves with current requirements up to 200 ma.