Snow Equipment Owning/Operating Trip springs on snow plow were too stiff

Chuck4310 · Jan 31, 2009

Solved this problem. My Curtis plow came with 4 springs. Way overkill for me.
I'd be plowing along and inevitably hit something and POW, it would practically throw me out of the seat!
Well, after I removed 2 of them it's better.

There is also a hydraulic relief device mounted on the plow. Does anyone know how it functions? Are they adjustable?

kennyd · Jan 31, 2009

The relief valve is called a "crossover relief valve" or "cushion valve". It's purpose is to protect the blade and framework by allowing the blade to move if it hits a immovable object. Say the blade is angled full left-so the right side is furthermost forward...and you hit a curb with the right side-the relief will trip allowing the fluid to escape the right cylinder so the blade will straighten out.

They are usually adjustable-but I would not mess with it...

Clear as mud?

ronjhall · Feb 1, 2009

My 6 1/2' Curtis came with only 2 springs. Trip works very well for my size tractor.
The hydraulic relief valve also works very well. But has no adjustment.

Chuck4310 · Feb 1, 2009

kennyd- I've hit objects with the blade angled and I don't think the relief device operated. The tractor sometimes shudders to a stop and the blade is still angled. It doesn't happen often, but I plow rough uneven ground.
It's almost like I would like to see the relief operate sooner than put the stress on the loader frame. That's why I removed two of the trip springs.
I guess my question is how do I know that the device works and is it set at a point that will protect the structure of the plow?

ronjhall- Mine is a 6 1/2' also but came with 4 springs. How can you tell that the hydraulic relief valve is working? Mine is a small rectangular block mounted on the plow.

Chuck

kennyd · Feb 1, 2009

Chuck, Why not call Curtis and ask them what it's set for?

JB4310 · Feb 1, 2009

kennyd said:
Chuck, Why not call Curtis and ask them what it's set for?

Probably has to be set stiff so it doesn't go into relief when pushing heavy snow load. I think it's there more to protect against serious damage, not to make comfortable stops when hitting stationary objects.

As far as the 4 springs, it does seem overkill and those springs don't look wimpy, 8' fisher plows only have 2 springs.
But you could have unloaded them with the threaded adjusters, they look cranked down pretty tight, don't know if that would have softened it enough though.

JB.

This is what happens with no relief valve,

ronjhall · Feb 2, 2009

Chuck4310 said:
kennyd- I've hit objects with the blade angled and I don't think the relief device operated. The tractor sometimes shudders to a stop and the blade is still angled. It doesn't happen often, but I plow rough uneven ground.
It's almost like I would like to see the relief operate sooner than put the stress on the loader frame. That's why I removed two of the trip springs.
I guess my question is how do I know that the device works and is it set at a point that will protect the structure of the plow?

ronjhall- Mine is a 6 1/2' also but came with 4 springs. How can you tell that the hydraulic relief valve is working? Mine is a small rectangular block mounted on the plow.

Chuck

The blade changes angle position. The trip works before relief valve. I have a rock at end of my drive. It is high enough that trip does not work. But angle will change when blade catches it at speed. It depends on conditions. If I have little weight on front wheels tractor will slide sideways before tripping relief valve. Happens most often when blade is not angled.

NHbotanut · Feb 3, 2009

I picked up the Curtis 6 1/2 plow this year, and it was manual. Curtis wanted $700.00 for the kit to convert it to power angle. I picked up 2 cylinders, hoses, and a cushion valve for under $300. Took me 10 minutes to install. The cushion valve has a preset PSI. Generally around 2500 to 3000. The place I bought the valve asked if I wanted to beef it up to 3000, but I wanted the lower PSI to protect the tractor. I have had the trip springs work a couple of times, but I have not hit anything to trigger the valve yet. Here is a pic of the hookup.

Chuck4310 · Feb 4, 2009

JB- I agree that the relief valve must be set higher than the trip springs to protect the tractor. It just seems that mine has taken some serious hits in a way that didn't cause the trip springs to work and I never noticed the blade change angle as if the relief valve operated.
The springs may not look it but they are slightly loose. Any looser and the blade would flop foreward.
Is the picture your plow? How did that happen?

ronj- This may be what is happening. The impact is sending the tractor off to one side due to the slippery conditions and lighter front end.

NHbot- Yours looks very similar to mine including the position of the relief valve. Yours looks permanently mounted. No quick connect?

kennyd- I may just call them and get the scoop.

Thanks for the comments guys.

Chuck

JB4310 · Feb 4, 2009

Chuck4310 said:
JB- I agree that the relief valve must be set higher than the trip springs to protect the tractor. It just seems that mine has taken some serious hits in a way that didn't cause the trip springs to work and I never noticed the blade change angle as if the relief valve operated.
The springs may not look it but they are slightly loose. Any looser and the blade would flop foreward.
Is the picture your plow? How did that happen?

Thanks for the comments guys.

Chuck

Yeah, after looking at the picture I see the springs aren't stretched at all, in which case if it trips to easy with just the 2 springs you can tighten those 2 up a little.

That's not my plow, I saw it at the JD dealer, they were trying to sell it cheap as is, looks like it hit something HARD. It's made by Horst Welding, which is the same company that makes my pallet forks, looks like it's well made.

JB.

NHbotanut · Feb 4, 2009

Chuck, I mounted the relief valve with a U clamp. I will make permanent adjustments this summer. The hoses have the quick connect mounted up on the loader that I use for my grapple.

PILOON · Feb 4, 2009

Most plow set ups use 2 single action cylinders to angle the blade.
Extending one retracts the other and the protection or crossover valve simply dumps the pressure from the impacted or overloaded side over to the other cylinder circuit thus saving fluid.

Only the extended corner of the plow is protected and not the inside (or curbside) which is the side generally that works hardest.
Being already in retracted mode there is no hydraulic fluid to dump.

If we were to plow snow away from the curbs to the center of the road and snag the curb with the extended corner then the crossover valve would 'dump' and blade would be protected.
Probably the main protection would be in cases where the operator catches manhole covers or protruding water valves type of situations

If I recall setting is 1500 PSI+/-

Naturally if pushing with the blade straight, both corners are 'crossover protected' therefore an impact would angle the blade and make your front end slide sidways and lessen the impact .(into a parked car? or the house?)

Chuck4310 · Feb 5, 2009

NHbot- I was referring to how your plow is connected to the loader arms. Have you considered a quick connect device?

PILOON- Thanks for your explanation of the relief valve. Makes sense. It gives me a better understanding.

The attached pic is of one of my bigger snow piles.

Since the areas I plow are all dirt/gravel roads, I set the skid shoes down enough to lift the blade up in the beginning of the winter. As time goes on and the roads ice up. I set the blade lower to scrape the new snow clean. It also makes it smoother with less obstructions to trip up the plow.

Chuck

NHbotanut · Feb 6, 2009

I did look into changing to the quick connect system, but it extends the implements, and I loose weight lifting ability.

Changing the pins out really isn't that bad once you get used to it. I learned the biggest thing is to have the tractor and implement on solid level ground and it will go much quicker and smoothly.

Chuck4310 · Feb 8, 2009

I'm assuming this is the relief valve.
Anyone recognize it or can educate me further?

Chuck

kennyd · Feb 8, 2009

Yes, that is your crossover/cushion relief valve. What is in the other hole on the ends, and witch hose go to the cylinders-the ones on the end or the sides?

Chuck4310 · Feb 8, 2009

kennyd- The side hoses ( those facing the loader arms ) go to the cylinders. There is an extra plug/blank in each side.
Front and back are from tractor.

Chuck