ELECTRICAL CONTROL SYSTEM FOR A HYDRAULIC POWER SYSTEM OF A TRACTOR

摘要

An application of the basic system of patent application Ser. No. 149,065 for operating a remote hydraulic valve. An electro-hydraulic actuator is mechanically linked to the control member of the remote valve. An input control signal is generated by multiplying a signal from a control handle position transducer by a scale factor constant produced by a full control setting with a gain control circuit. The gain control circuit also operates to set the constant to unity in case the signal from the handle position transducer exceeds a predetermined level corresponding to a maximum control handle setting. The control handle itself has four positions: Float, Lower, Neutral and Raise. The handle is biased so that if the handle is released from any position other than Neutral, the handle will go to the Neutral position provided a detent is off. The detent is put in the "off" position by an electrical solenoid which is actuated whenever the supply pressure to the remote valve exceeds a set value. By this means the handle is released from either Raise or Lower position when conditions occur corresponding to the remote valve hitting the end of its stroke or it is being overloaded.