Electronic speed control EHS.

EHS takes up an electric pulse signal related to rotational movement, e.g. the speed of a shaft, the speed of a vehicle. The pulse signal is converted into a proportional signal that is applied, via port A on the proportional valve, to control the speed of a hydraulic motor. EHS also gives the possibility of infinite flow regulation. EHS and PVG create a variable electrohydraulic gear. EHS controls the flow from the proportional valve, in relation to the frequency of the electric signal from a tachometer pulse source. EHS contains two potentiometers, used to set the frequency necessary to give maximum movement of the proportional valve and compensate for leakage in the hydraulic system itself. An externally connected potentiometer allows the infinite regulation of the ratio between frequency and flow. When a frequency is applied to EHS, the proportional valve immediately functions to give the corresponding flow. To ensure linearity between frequency and flow, EHS compensates for the progressive flow characteristic of the proportional valve.