Any body can explain how this circuit works. This is Hiab truck mounted crane circuit. I want to know that how each individual valves work & what will be the flow path. can u explain with the same dwg editing by other color by showing flow paths.

That is a complicated circuit to say the least and not one that can be reliably diagnosed from the schematic alone.

I have made color coded schematics of many machines over the years and used them in classes for the Engineering and Maintenence persons who would be working on them. Often even the Machine Operators were involved in a condensed class.

I usually found the schematic was not curent, especially on machines that were older, and always insisted on seeing the machine and tracing out all the components and how they were connected. NEVER FOUND EVEN ONE SCHEMATIC THAT WAS CURRENT IN 25 YEARS even on circuits that had just been installed.

On top of that all the components, with cutaway drawings, should be included in any documentation, and with a writeup on how they should operate in the circuit and pointers on adjusting pessure settings, manual overrides, etc. along with failure modes and what to do when a problem is found.

Needless to say that is not INEXPENSIVE when a knowledgeabl person is involved but can payback many timmes over in lost production.

I suggest you contact a person in your area that knows hydraulics and can go over the circuit to make sure the schematic is up to date and who can find literture on all the components, with cutaway drawings, and have them make training books that you and your personnel can have for future reference.

I could certainly do up a multi colored set of drawings for you, but that is something I charge $$$ for. It's too time consuming to do for free.

If cost is an issue your best bet is to familiarize yourself with the basics via the E books found on http://www.hydraulicspneumatics.com/200/eBooks/. Keep referring back to your schematic and slowly piece things together. If you have a specific question that you’re having a problem understanding, by all means post it.

For diagnostic problems concentrate on the working area only as oil flows through the valve to do the work at the cylinder. Dont get caught up with other functions that arent being operated(unless bypass is involved). Hiab are a very good company to liase with, and have found them to be very reliable. I prefer the palfinger design but hiab is still great. Call them and ask for what you want as I know they have separate circuit diagrams for these machines. You will get the run around but ask for the service manager, he or she should be able to point you right

Agree with Doug H and Newmanite, you have to deal with it your self.
But I also understand it is complex system. It get simpler than it looks when it is brooken down into more isolated pieces.
Analysing these kind of systems need some experience, and also knowledge how a crane like this operates.

This crane system is applied on the 14 or 16 tonmeter cranes....144/166...and there is some product information to find on
http://www.hiab.com/Products/L...2773&productId=18571

It also helps to have knowledge about how this control valve is designed.
For example this little shuttle valves below the control valves is located inside the control valve spool.

Expect (not 100% sure) control valve,V91, and system design coming from PARKER HANNFIN, Former Swedish VOAC,
Parker-H have almost 100% of scandinavian crane control valve market, and on some of the John Deere and Komatsu logging equipment

This system is a FIXED PUMP and a CLOSED CENTER, LOAD SENSING (LS) system.
Try to follow oil path from pump when all control valves is in neutral. You will find that there is a by-pass valve close to the pump, where it says "Shunt".
The valve spring sets a low pressure enough to charge system. This charge pressure will hit all control valves.

When a control valve is actuated a LOAD pressure will come back to the by-pass valve and ADD on to the charge pressure (spring), see the "S" line. That will set the system pressure.
If multiple functions are operated, the highest load pressure get priority via the small shuttle valves below the control valve.

I have attached some rough samples, excuse my coloring....

Good Luck

Thanks. Can you explain it briefly ne by one operation with the each seperate circit marked by some other colour.

quote:

Originally posted by Sundar:
Thanks. Can you explain it briefly ne by one operation with the each seperate circit marked by some other colour.

well I did do more than I intended....I am not going to do the whole student project for you...you have to learn by your self...

Here is the deal...you post two cut outs with you suggestion of "painting/coloring" and your interpretation of one part of the system.....

Lets start with those legs that stabilize the crane....two for leg up/down and two for leg in/out...

Are these functions LS, load sensing?

How do you get oil to their control valves, and show the oilflow for the right leg going up.
Also what is the purpose with the #4 pilot check valve?

What is the maximum pressure for these functions?

Paint pump oil RED and return to tank oil BLUE
When you are done with this one I will let you do another one.

I used MS Paint so that should work for you too.

Good luck!