Valve working principal

[KAGAME]

Hello!
My name is KAGAME Yves, I am an electromechanical engineer. I need an assistance from you guys about the KRACHT hydraulic valve that I don’t understand it working principal. I took it from a Caterpillar compactor, but I still don’t understand how it been interacting with other components. Below are some of its photographs to check on if you can recognize it.

 

[mk3223]

Suggest to contact the KRACHT vendor for the manual of the D598 Werdohl. Per Google search, D598 is a hydraulic pump, instead of valve.
Good luck.