Relief Crossover Valve

[jgbanshee]

I have a Curtis snow plow that attaches to my FEL. It has a crossover relief valve from the factory.

I contacted Curtis for the valve relief setting on my plow. They said that it is set at 1500psi at the factory. I then asked them if it could be adjusted. They said that I could turn the allen head plug to adjust the relief, there is a spring behind the plug that compresses. One turn equates to approx. 100-200 psi. Next, I asked what the max PSI setting is on this valve. They said that the allen plug could be turned all the way in and then have no relief but it could damage the hoses and/or tractor.

Does that mean that I could potential achieve 3500psi relief from this valve?

 

[J_J]

Most relief valves come with a factory setting and give an adjustment range. It may be possible to turn the screw down until the spring is fully compressed. and that would insure that you would have no relief. You want a relief setting to protect the valve, motor, or cylinder, usually about 100 psi below max pump pressure. Sometimes you will get spikes in the hyd circuit, that exceed the pump rating.

 

[kennyd]

I have a Curtis snow plow that attaches to my FEL. It has a crossover relief valve from the factory.

I contacted Curtis for the valve relief setting on my plow. They said that it is set at 1500psi at the factory. I then asked them if it could be adjusted. They said that I could turn the allen head plug to adjust the relief, there is a spring behind the plug that compresses. One turn equates to approx. 100-200 psi. Next, I asked what the max PSI setting is on this valve. They said that the allen plug could be turned all the way in and then have no relief but it could damage the hoses and/or tractor.

Does that mean that I could potential achieve 3500psi relief from this valve?

Who knows...the Prince XORV's come in a "range" of adjustment according to the Surplus Center catalog.

Do you think you need to adjust yours?

 

[J_J]

jgbanshee ,

Why would you even consider a setting above your pump max pressure. You would set it for the lowest rated component in the circuit.

 

[jgbanshee]

Kennyd,

I dont want to adjust the valve on my Curtis. I want to buy a valve for my 9' Meyer that is on my larger machine. I have 1/4" hoses on the Meyer plow and the Curtis valve has 1/4" ports, nice compact size, aluminum. I might just get the Prince valve from Surplus Center that is 1500-3500psi with 1/2" ports and just get fittings to attache the 1/4" hoses.

 

[jgbanshee]

J_J

My tractor relief is 2500psi.

 

[J_J]

If your FEL valve has 2500 psi relief, , then the relief for anything else in the circuit should be the same. but you could set it even less than the FEL valve in order to protect a cylinder with a lower psi rating.

 

[jgbanshee]

Correct. I guess I dont understand how the pressure on the tip of the plow blade (side of plow that is out in front when angled) related to the relief valve setting.

 

[AKKAMAAN]

Here is some clearification about relief valves.
A valve located between pump and control valve, CV, is the main protection for the whole system, that means the pressure coming from the pump.
Let's say that is set at 2500psi. This valve is aka pump protection valve.

A relief valve located between the CV and the actuator (motor), is meant to protect the local part of the system between the CV and the actuator. This valve is aka motor protection valve. This valve can either be a pressure reducing valve, set to a lower pressure, let's say 2000psi, or be set at a higher pressure, lets say 3000psi. It all depends on what size of mechanical stress the actuator and it's mechanical construction can take, type snowplow blade etc.
Running a snow plow blade into a curb will force stress into the construction which could be damaged if hydraulic pressure wasnt reliefed. You do want that blade to resist some smaller bumps and ice chunks with out folding over to the other side......that will determine your pressure setting on this crossover valve.

A cross over valve is a relief valve used on actuators with the same piston area (volume) in both directions. Either by a double rod cylinder, or two cylinders hooked up cross parallell. It will also work with a hydraulic motor.
A crossover valve dumps the whole relief volume to other side of piston.

A regular releif valve dumps part of relief volume to tank. Compensating volume to the low pressure side will enter via a check valve, aka anti cavitation valve.

 

[kennyd]

Correct. I guess I dont understand how the pressure on the tip of the plow blade (side of plow that is out in front when angled) related to the relief valve setting.

The two are NOT related. The setting of the main PRV has nothing to do with this. Just as AKK wrote-it is to protect the circuit between the valve and the plow. The main PRV can do nothing to protect that because the valve is in neutral, and the work ports are blocked thus isolating them from the main PRV.

The 1500-3000PSI XORV would be a good choice for your larger plow, start at the lowest setting and adjust it higher if it trips to easily.

 

[jgbanshee]

How do you check the relief pressure on a crossover valve?

 

[J_J]

Tee in a gage before the valve. When you make the cylinder work hard, the pressure will build up and indicate on the gage. You may not be able to get the cyl to work hard enough to cause the relief to activate, unless it is set real low. Picking up a plow is not that big a deal with some cylinders.

 

[Smalljobs]

I'm running a 6.5' Meyer with the same Curtis aluminum cross over and 1/4" hoses. It angles fast enough and I expect all will be OK this winter. Single acting or "ram" plow cylinders don't displace much fluid and most plow cylinder pistons are actually the rod itself. Inside is a simple guide ring but the actual delta P area is based on the rod dia.

 

[AKKAMAAN]

How do you check the relief pressure on a crossover valve?

T in a 5000psi gauge between pump and controlvalve.
If the crossover is set below the pump relief setting, you can operate the circuit (actuator) to end stop, hold valve and check the pressure....the crossover will open before main relief valve and it's pressure setting will show on the gauge. If crossover is set higher than main relief valve.....you might have to increase (temporarely) main valve (while operating cross over circuit) setting till crossover opens......be careful, do not exceed 3000psi. Make max 1/8 turn (clockwise) at the time....best if you can have a helper to operate valve....you should be able to hear when reliefs opens....they also will go hot quickly when opens....

Repeat this the opposite direction!

If you figure crossover is set over 3000psi, you have to make sure cylinders, hoses, crossover and controlvalve are rated that high....Usually components at this level are rated max 3000psi, 2500psi not uncommon either.....

 

[jgbanshee]

So I should probably put my 5000psi gauge inline with my rear remotes to get a true relief reading before I do anything with the crossover. Do I have to T into the lines or could the gauge be hooked right to the crossover valve?

 

[AKKAMAAN]

So I should probably put my 5000psi gauge inline with my rear remotes to get a true relief reading before I do anything with the crossover. Do I have to T into the lines or could the gauge be hooked right to the crossover valve?

I would just T it between pump and CV. It will read the Crossover,CO, when CV is operating...(if CO is set lower than main relief)