hello dear
How are you people out there
Does any of you have documents or circuits to test various hydraulic valves like pressure valves, direction valves and flow control valves. and also proportional and servo valves.There are certain paramenters which are needed to be calculated or checked before saying that the valve is pperfect for installation especially where the operation is critical like position control and other such applications like leakage, repetability, hysterisis and so on..... .Also can you please provide documents related to the testing of hydraulic motors as well
i am waiting for a positive reply and i hope you people help me out
with kind regards
Muhammad Umair Nazar

In the years I've been on the Fluid Power Forums I have seen several post's from Fluid Power Rebuilders. 99% of the post' were questions about how to diagnose a circuit failure for one of their customers. Most of the rebuilders are originally from the Machinist trade and know types of Fits and Tolerances but have little knowledge of Fluid Power application.

Manufacturers sometime show in their literature what is acceptable Bypass from Port to Port on new factory components but don't give tolerances on the fit of components.

I don't believe your local rebuilders will be forthcoming with the information either. It is usually top secret information to reduce competition.

However, if you are a User and want to keep the repair in your plant, a Reuilder may help since they know that it is usually a short time until you come back to them for most of your repair work.

At least that has been my experience.

Thats a lot Nazar, but most testing are based on how the component works, specifications and performance curves!!! Proof pressure= 1.5X the maximum operating pressure. Internal leakage(drops only ... my estimate is less than 4 cc/min) are based on manufacturers, but standard industrial/mobile catalogue have no internal leakage data. IMO, Oscilloscope is used to determine repeatability, hysterisis, etc. Load test(on motors) is 1.5X rated load too.

This is just an opinion... are you doing aircraft hydraulics?

hello dear
Thanx for the reply
I am not doing aircraft hydraulics.
I wanted to know how the companies test the hydraulic valves , i mean to say what techniques they follow to test various parameters. Like you said leakage , now what all is the circuit or how they count the drops, there must be some arrangement/circuit/method to go with.
Also talking about the testing of proportional valves , how do they test the hysterises, what circuit they make to test the hysteresis, there will be some arrangement or method .
Making it simple, if some one takes a proportional valve to me and i claim that i have the testing capabilities to test proportinal valves , then ho am i going to test that valve.What arrangement should i have in my lab /shop to test various parameter.
I am waiting for practical replies
With kind regards
Muhammad Umair Nazar

If you really know a hydraulic component, then you can test it...

Connect it to the power unit having the rated flows and pressure. If you can have a flow meter/pressure gauges at the high pressure or low pressure side(almost across the valves)

For conventional valves: (But not necessary)

DCV- connect a source to "P" port(at pressure you want) and check the leakages on "A", "B" and "T" if it is a closed P after 2 minutes. Then you can energise it to "A"/"B"("T" to tank) for 2 minutes and check the leakage on "T" and/or B/A. Now you check the pressure drop at rated flow on each actuation. Proof pressure by connecting all the high pressure ports. T port is weak on most valves, so enquire about it...

Pressure valves(RV)- check for cracking pressure, full flow pressure and reset pressure.

Flow controls- check for adjustability, pressure drops and flow changes for varrying loads(pressure/temp compensated).

There are a lot and you can make a book out of this topic...

Then use the same process on proportional and servo but add more processes upon knowing what it is and how it has to work, respond etc... etc... etc...

BTW Nazar, I just would like to ask some personnal questions from you but i dont know how to use the private message options... maybe I could e-mail you...

This message has been edited. Last edited by: maglub,

Hello dear
My e-mail address is :
umair_nazar@yahoo.com

Waiting for your mail
With kind regards
Muhammad Umair Nazar

any one who wants to contact me can call me on my number:
+92 334 5350161