Squealing control valve

[bar]

I have a problem (that may be unique) that I couldn't find any information on from a search. I have a Zetor 3340 with an Allied FEL. I have fabricated a frame for a power angle plow blade and bought a Prince 4-way, open center control valve to control the power angle function. The Zetor system is 8.5GPM @ 2600PSI, open center. I wanted to keep the loader tilt function for the blade so didn't want to use either of the loader controls for the PA function.

I connected the FEL control output to the input of the Prince control and returned the output of the Prince control back to the tank. The Prince has a check valve at the input to prevent reverse flow. The A & B ports go to a pair of SA cylinders.
Now the problem. When I angle the blade it moves far slower than I expected and the Prince control makes a whining noise. The FEL controls still work fine.
Pressure relief on the Prince control is at factory setting of 1500PSI.

Can anyone tell me if there is something inherently wrong with this hookup or have some thoughts on what the problem could be.

Sorry its so long but wanted to provide adequate info first time around.
Thanks for any inputs. bar

 

[SnowRidge]

Sounds like the relief is opening. What range of adjustment is available on the relief? I assume the Prince valve is rated at least 2600 PSI.

Is there a proper path for the fluid to flow back from the single action cylinders?

 

[kennyd]

Squealing is usually cause by the PRV (Pressure Relief Valve) as SR just indicated. The relief on the new valve should be set close to or at the system pressure for your system.

One other problem that could cause it since you indicated slow operation would be a restriction in the lines...you didn't go crazy with Teflon tape did you?

 

[bar]

kennyd & SnowRidge, Thanks for the responses. I thought the noise was from the relief valve. Prince PR range is 1000 to 3000 PSI and spec sheet says its preset to 1500PSI.
I have read not to use teflon tape. I used teflon based paste and was careful to keep it below the first thread of NPT fittings. I checked valve performance with air and the valve worked as expected ie with port A enabled, Port B was open to the return line.
I think it must be a restriction. I used one of my new 15' lines when testing the valve with air but didn't test the other one. PA performance acts the same in both directions.
If I use the PA function sparingly will it cause any damage to the system if I don't fix it before warm weather next spring?

 

[SnowRidge]

Adjust the relief to match your system pressure under normal operating conditions. Your system is delivering more than 1500 PSI, so the relief opens. You really should put a gauge on it to see exactly what the pressure is when it opens.

 

[kennyd]

Yeah, Get a gauge and set it properly...You can but them online or at TSC for under $20. You will also be able to check your other PRV's to see if your whole system is up to spec.

 

[abcrepair]

I have a problem (that may be unique) that I couldn't find any information on from a search. I have a Zetor 3340 with an Allied FEL. I have fabricated a frame for a power angle plow blade and bought a Prince 4-way, open center control valve to control the power angle function. The Zetor system is 8.5GPM @ 2600PSI, open center. I wanted to keep the loader tilt function for the blade so didn't want to use either of the loader controls for the PA function.

I connected the FEL control output to the input of the Prince control and returned the output of the Prince control back to the tank. The Prince has a check valve at the input to prevent reverse flow. The A & B ports go to a pair of SA cylinders.
Now the problem. When I angle the blade it moves far slower than I expected and the Prince control makes a whining noise. The FEL controls still work fine.
Pressure relief on the Prince control is at factory setting of 1500PSI.

Can anyone tell me if there is something inherently wrong with this hookup or have some thoughts on what the problem could be.

Sorry its so long but wanted to provide adequate info first time around.
Thanks for any inputs. bar

It is possible that the prince control valve has a "power beyond sleeve" installed in it witch would block the return oil comming from the angle cyls. it would be a big nut with a sleeve atached to it at the outlet port of the prince valve. I would not increase the pressure stetting on the prince valve. you might run into trouble if you use the factory control valve and the prince valve at the same time.

 

[kennyd]

It is possible that the prince control valve has a "power beyond sleeve" installed in it witch would block the return oil comming from the angle cyls.

That is an excellent thought!

I would not increase the pressure stetting on the prince valve. you might run into trouble if you use the factory control valve and the prince valve at the same time.

What trouble could you run into? Please explain why you would want a relief set so low in a system that's max pressure is probably 2000-2500 PSI?

 

[banjodunn]

Hi adjust the relief valve on the prince right up you should already have a relief valve in the main fel valve as well as the tractor relief we do this all the time and have not had a prob in the last 20+ years unless you play with the main releif or the fel relief you are going to be safe 1500psi is way too low for proper operation

 

[bar]

The Prince valve does not have the large nut near the outlet port. I pretested the valve with air and know that air passes freely thru the valve from input to output when the control is spring centered. When I tested with air for which control position activated port A, I had to remove the inlet reverse check valve to get air thru because of the low pressure I was using. What I don't remember doing is testing to see if port B was open to the return line when port A was activated. I guess I'll have to disassemble and test for that .....and none of my many fittings leaked first time around!!http://www.tractorbynet.com/forums/images/smilies/smile.gif or call Prince. Would a standard 4-way control valve be designed that way?

Regarding system pressure, Isn't pump operating pressure dependent on load? The power angle frame is greased and can be swiveled by hand very easily with the cylinders disconnected.

I don't plan on ever operating the FEL controls and the Prince control at the same time.

Thanks again for all the responses.
bar