Is a Cross Over Relief Valve Important

[BAP]

How important is it to have a cross over relief valve on a snow plow for a small tractor. I am converting an old Fisher snowplow to fit the loader quick coupler on my Kubota B2020. I know there is a lot of talk on this site about using a cross over valve, but looking at some of the commercially made snowplows for small tractors, I am finding that not all of them put these on as standard equipment. They offer them as an option. Is it really necessary on a 22HP tractor, or not? I don't want to sacrifice the safety of my tractors hydraulics, but at the same time, I don't want to waste money on a valve and extra hoses that I don't really need. I am wondering if on a small tractor plowing at a reasonably slow speed if it is really necessary.

 

[kennyd]

I believe they are very important to protect the hardware. Even on my small tractor I can "trip" the blade side to side when hitting something solid.

 

[George2615]

A snow plow for a truck uses 2 single acting cylinders to angle the blade. Hooking this setup on a tractor may put excess stress on the non active cylinder when you angle the blade. I am doing the same thing this weekend. Converting a 7'6" Diamond plow to my tractor loader QA. My old Diamond single cylinders were trashed so I removed them and will install a single double acting cylinder to move the blade left or right. I will start a new post with pics of my install next week.

 

[oldnslo]

How important is it to have a cross over relief valve on a snow plow for a small tractor. I am converting an old Fisher snowplow to fit the loader quick coupler on my Kubota B2020. I know there is a lot of talk on this site about using a cross over valve, but looking at some of the commercially made snowplows for small tractors, I am finding that not all of them put these on as standard equipment. They offer them as an option. Is it really necessary on a 22HP tractor, or not? I don't want to sacrifice the safety of my tractors hydraulics, but at the same time, I don't want to waste money on a valve and extra hoses that I don't really need. I am wondering if on a small tractor plowing at a reasonably slow speed if it is really necessary.

Presuming the Fisher plow has two single acting cylinders the cross over relief is cheap insurance. Even only going three MPH and catching something with the corner of blade is heck of a shock load and stresses the frame immensely.

If a single doube acting cylinder like George2615 is used then cross over reliefs get more complicated since the rod end of the cylider has a different volumetric area than the cap end.

 

[Coyote machine]

The cross over saves the loader on any size tractor. Otherwise wracking the loader arms is a foregone conclusion. Saving $ is not the point, saving the more expensive loader is the reason for the valve. Truck plows are attached to subframe attached to the frame rails. The tractor loader is designed to take direct front on forces from dirt, manure, etc. Snow plowing entails side and corner forces the loader was not designed to encounter. When a crossover valved plow hits an immovable object the force is redirected so the shock is lessened and the loader is relieved of the impact forces.

 

[J_J]

Crossover relief.

If you want the surge protection, you will need one.

A crossover relief valve is used in systems that require crossover relief protection such as reversible hydraulic motors, or systems that require a cushion valve such as a double-acting cylinder.

 

[jmc]

Is the idea of a crossover relief valve because it can be set to kick in at a lower pressure than the tractor's relief valve or is it that the tractor's relief valve only works for hydraulic pump generated pressure?

 

[J_J]

When a valve is in neutral, the cyl circuit is locked and the crossover relie is the only protection for the cyl, hoses, fittings.

You can set the pressure at what ever level you desire. If the cyl is a 2500 psi cyl, then set the relief valve at about 2450 psi.

 

[RickB]

A snow plow for a truck uses 2 single acting cylinders to angle the blade. Hooking this setup on a tractor may put excess stress on the non active cylinder when you angle the blade. I am doing the same thing this weekend. Converting a 7'6" Diamond plow to my tractor loader QA. My old Diamond single cylinders were trashed so I removed them and will install a single double acting cylinder to move the blade left or right. I will start a new post with pics of my install next week.

I hope you don't think installing a double acting cylinder eliminates the need for a crossover relief.

 

[avc8130]

If you've ever plowed previously, you already know the answer to this question. You NEED some form of crossover relief.

Not having one is just asking to do damage. So you save a few bucks and skip the relief. Now you plow that driveway you've driven down 200 times. Sure enough, you didn't realize the kids left something out and it froze SOLID to the ground. You catch that with the corner of your blade. At the BEST case you will blow a hose. Not a terribly expensive, but think of this. You are plowing the driveway to make it passable by a car. That same car you will probably now NEED to go get the hose you just broke.

Snow plow setups need to be reliable. Part of that reliability is planning for the stuff that goes wrong and giving the plow the best chance it has to make it through the storm. Crossover relief is part of that plan.

ac