Crossover Relief Valve or Not?

[ovrszd]

Before answering I had to reread the thread Title: "Crossover Relief Valve Or Not?" Based on that title my answer is "it's your choice".

If your thread title had asked a question similar to this the answers would be more definitive.

Does a CRV help protect my system?: YES.

Can I use my system without one?: YES.

Do you use a CRV on your snow plow?: NO.

If building a plow setup (which I did) would you use one?: NO. Because of my specific usage I didn't feel I needed one.

 

[lostcause]

This post was more about "is there already protection built in?" than it was "should I have one?"

Someone mentioned the loader valve, but that's not even part of this equation. I'm hooking the plow angle circuit to an electric / hydraulic 3rd function valve that sits directly behind the operators station, betweenand behind the rear tires and above the rockshaft housing. it has factory plumbing all the way to the front of the loader frame and is controlled by an electric thumb switch on the loader control. to date I have only used it on a grapple with a single cylinder - dual acting. I asked this because the factory Deere (Frontier) loader mounted snow plow (AF11) does not have a dual crossover relief valve according to the parts schematic . I was curious whether there was something about the 3rd function valve on these that would provide that sort of relief protection. The much older subframe mounted Deere plow (366A) has a dual crossover relief valve built in. Since that plow was only attached with the loader removed it would utilize the loader valve and its associated hydraulics for up/down and angle.

 

[Gordon Gould]

I have a CRV on my tractor plow (my truck plow also - Fisher builds them into their truck plows). The CRV almost never fires while plowing normally. The mechanical trip edge seems to provide adequate protection in both vehicles most of the time. However, when I stack or pile snow, which I have to do often, the CRV's fire quite frequently. When you push packed snow up into a pile the forces on the blade are very high and not evenly distributed across the blade. The CRV will protect your hydraulic components from the excessive pressures that would be generated if it wasn't there..

gg

 

[Industrial Toys]

I too ran my 6200 Deere blade off the electric valve on the valvestack, rear of tractor.

IF, I was doing contract work, in unfamiliar places, I think I would opt for a relief valve. Not only unfamiliar, but you tend to be in more of a hurry to get things cleared. Not a good combination.

 

[lostcause]

I have a CRV on my tractor plow (my truck plow also - Fisher builds them into their truck plows). The CRV almost never fires while plowing normally. The mechanical trip edge seems to provide adequate protection in both vehicles most of the time. However, when I stack or pile snow, which I have to do often, the CRV's fire quite frequently. When you push packed snow up into a pile the forces on the blade are very high and not evenly distributed across the blade. The CRV will protect your hydraulic components from the excessive pressures that would be generated if it wasn't there..

gg

Yeah, I'm familiar with how they work - both within a truck mounted plow and a stand-alone valve on a piece of equipment. I've had a few Fisher plows over the years - I live about 20 miles from where they make them and you see them at least 10:1 over all other brands combined here. I've had 8' & 9' straight blades, but the most recent was a 7'2" HS on a 2016 Colorado. All parts in that system were very light, to match the truck, but they also set the relief valves so that it took very little pressure to trip the relief and let the blade angle back and the fluid bypass (not to be confused with the blade trip system - that's all mechanical). I figured I would bend something because the metal was so thin, but the system was balanced perfectly so that didn't happen. I'm still stuck on why Deere didn't add one to the AF11...

 

[wdchyd]

Fisher and Meyers elec pump factory CRV’s are set at 3000psi (to protect the cyls), Fisher main PRV’s are set at 1750 psi (Meyers 1650) to protect the pump.
Not having a CRV results in a blown cyl barrel (or bent FEL frame) Seen it several times.