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Help required to understand hydraulic system

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  • Help required to understand hydraulic system

    Good day everybody.

    I have a 4 x 4 Mercedes tractor rigged with a Hiab 100AWV loader crane & a Rotzler hydraulic winch. It was professionally built in Sweden to be used in the powerline construction industry. With an estimated weight of 6 to 7 tons and a crane reach of about 11 meters

    It has a twin hydraulic pump that runs off the tractor PTO, one pump feeds the loader crane circuit and the other feeds the winch and outrigger circuit.

    The crane, winch and outriggers all function 'normally' and I am assuming that all pipes are correctly connected as designed.

    The winch/outrigger circuit has a mechanical over pressure valve between the feed and return, located directly after the inline high pressure filter. The returns discharge directly into the tank.

    The crane circuit has two pipes going back to the tank. One from the crane valve block discharging through a magnetic filter mounted on the tank (like a 'normal' return circuit). The other, is a T off from the pressure side directly after the inline high pressure filter discharging through a solenoid valve fitted to the tank.

    Each of the four outriggers is fitted with a XMJ-A160 pressure sensor. Each sensor (each with 2 wires) is wired back to a common junction box.

    Other connections going into this common junction box are;
    Power in from dashboard (fused)
    Power out to winch control
    Power out to solenoid valve mounted on tank

    Within the junction box are block connectors and a contact switch and a small inline resistor and an earth connection.
    Some wires are cut and there is evidence of insect infestation.

    Can anybody help me with the following questions;

    Why is there a T off on the pressure feed side of the crane circuit going directly to the solenoid valve on the tank?

    What action/fault would trigger the mechanical pressure valve on the winch/outrigger circuit?

    I assume the pressure sensors on the outriggers are a safety feature of some kind but what would trigger a sensor and what would that electrical signal activate?

    How would I rewire the electrical junction box?

    Any advise would be much appreciated. Photos and a hydraulic circuit sketch are available.

    Thank You