There are many types of valves used in excavators. Two are important: the main valve and the pilot valve. Is the pilot valve is controlled by the operator and the main valve is controlled by the pilot valve? But I can't imagine this system properly. How can the pilot valve control the main valve? Additionally, I am not able to understand the flow of oil after pumping. Will it go to the main valve or the pilot valve?

  • $\begingroup$ How did you get on with the course suggested here? engineering.stackexchange.com/a/54548/10902 $\endgroup$
    – Solar Mike
    Commented Mar 21, 2023 at 7:42
  • $\begingroup$ I asked the question here to get the accurate answer in a few lines. I dont want any course or book link. $\endgroup$
    – Prerna
    Commented Mar 21, 2023 at 9:14
  • $\begingroup$ I gave you that simple answer as the first line in my answer. $\endgroup$
    – Solar Mike
    Commented Mar 21, 2023 at 9:19

1 Answer 1


Think of the pilot valve as a "lever" to control the main valve.

If you obtain a system diagram then you can follow what happens.

There are many texts available that describe the functions of all the parts in a hydraulic system. I have the set of Hydraulic books by Mannesman Rexroth Sigma, now part of Bosch, so I don't know if they still produce them. Worth searching for and reading.

This is a link to one of the series (they were produced in several languages, in fact they also produced a technical dictionary across 6 languages which I still find useful): enter link description here


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