Plow protection

[varmint]

I guess I have exhausted potential projects on our "new" tractor, now to just wait for some snow. I decided, as a final mod., to add a crossover relief valve to the plow's angling circuit. Easy, since the hoses were already two piece, and in the right lengths. If I ever use the plow, and do strike something, hopefully there won't be any damage.

 

[oldnslo]

Not to ruin your day varmint but... With double acting cylinders the cross over relief is of little protection when then load is trying to retract the cylinder. Reason for this is there is less volume in the rod end of the cylinder since the rod takes up volume.

 

[varmint]

I see what you mean... darn. I guess I will try to plow so the cylinder will extend if I smack something. Seemed like a good idea, and hopefully I haven't made it worse! I have a lot to learn about hydraulics.

 

[Coyote machine]

I have a HLA 2000 snowblade. I believe the black valve your hoses are connected into currently may be a crossover valve, but I'm not familiar with your model in particular. I suggest contacting HLA/Horst welding and verifying your particular blade options: HLA Snow

 

[varmint]

Like Coyote suggested, I spoke with HLA, and they confirmed what oldnslo observed- won't hurt, but probably won't provide much cushioning, either. I had noticed that their single cylinder HLA 2000 plow with the single cylinder came with the crossover valve, and they thought it really served no purpose. Go figure. Looks like I have a nice valve, for a project that needs it.

 

[LD1]

That is why I dont like a DA cylinder on a plow. Two SA cylinders are much better. Can easily incorporate a crossover, and plow moves both directions with equal speed, and equal force.

 

[Coyote machine]

Like Coyote suggested, I spoke with HLA, and they confirmed what oldnslo observed- won't hurt, but probably won't provide much cushioning, either. I had noticed that their single cylinder HLA 2000 plow with the single cylinder came with the crossover valve, and they thought it really served no purpose. Go figure. Looks like I have a nice valve, for a project that needs it.

Are you saying that HLA told you the crossover on my model snowblade 'serves no purpose'?
Why would they say that about a design that is their own?

 

[varmint]

Well, that depends if you have the single, double acting cylinder, or the version with two cylinders. I see they offer both. With the single cylinder, it doesn't provide much protection. See LD1's post above. Just what they told me.

 

[Coyote machine]

Well, that depends if you have the single, double acting cylinder, or the version with two cylinders. I see they offer both. With the single cylinder, it doesn't provide much protection. See LD1's post above. Just what they told me.

Got it. Just suprised that they would dis their own equipment design? I will follow-up with them about this. I read LD1's post already.

 

[skyhook]

That is why I dont like a DA cylinder on a plow. Two SA cylinders are much better. Can easily incorporate a crossover, and plow moves both directions with equal speed, and equal force.

I'm also lost when it comes to hydraulics, a DA cylinder is that a cylinder with "two" hose inputs? And does a SA cylinder only have "one' hose input?

 

[Danny C]

I'm also lost when it comes to hydraulics, a DA cylinder is that a cylinder with "two" hose inputs? And does a SA cylinder only have "one' hose input?

A double acting cylinder will have two hoses attached to the cylinder and "acts", or moves in two directions under its own power; in and out. A Single "acting" cylinder has one hose input and will only work in one direction under it's own power. They are typically installed as a pair. Each cylinder works in one direction only with the other pushing or closing its pair shut. Normally installed with a cross-over relief valve.

 

[varmint]

Well, I think all cylinders would have two hoses, so when they extend there's a way out for the escaping fluid. A double acting is just a cylinder set up to both push and pull against its load, whereas the single acting usually works in a pair, just pushing the load going out, not pulling in. Maybe somebody else can better explain this!

 

[LD1]

I'm also lost when it comes to hydraulics, a DA cylinder is that a cylinder with "two" hose inputs? And does a SA cylinder only have "one' hose input?

Danny C explained it well.

Well, I think all cylinders would have two hoses, so when they extend there's a way out for the escaping fluid.

There should be no fluid excaping, so no need for another hose. There are two types of SA cylinders. The type that is configured like a DA cylinder (or a DA cylinder used in a SA application). Those do have a port at the rod end and use piston seals like a DA cylinder. That rod end port is an air vent to let air out. It will also leak oil out if the piston seals fail. If it vented back to tank, you would never know if the piston seals were bad.

The other type is like snowplow cylinders. THey are a displacement type in that they do not have a piston or piston seals. Rather just a packing seal around the rod. Put pressurized fluid into the cylinder, the rod is what displaces.

 

[Danny C]

Well, I think all cylinders would have two hoses, so when they extend there's a way out for the escaping fluid. A double acting is just a cylinder set up to both push and pull against its load, whereas the single acting usually works in a pair, just pushing the load going out, not pulling in. Maybe somebody else can better explain this!

This web site explains it bett than I. Single Acting Hydraulic Cylinders | Best Metal Products A single acting cylinder uses a force other than its own to operate the ram back. This can be a spring, gravity or hydraulic pressur from another ram working in the other direction. All it needs is for the valve to be opened.

 

[varmint]

Ah- I am learning, and among other things, to keep quiet when I don't know what I am talking about! Having a forum where knowledge is freely shared is great. Thanks, guys.

 

[Coyote machine]

Here is what Daryl at horst welding, HLA told me. Daryl is the parts manager. He said the 1000 series is the economy plow and does not need a crossover valve and does not come with one because of the valve cost, around $200, and the fact that the blade is lightweight and designed as an entry level blade. He said some people do install their own valve BUT it does need to be backed off from the factory setting by 2-3 turns under the caps. Loosen the jam nut and back out each side, otherwise it won't release as intended on the 1000 series blades. He also confirmed for me that on the 2000 series with crossover factory installed and the single piston, DA cylinder, the crossover IS effective, and dumps fluid through the valve if something immovable is encountered.
I've had it release numerous times in the two seasons I've owned and operated it.

I hope the above clears up any confusion about the crossover valve's functionality, and need of use on the different plow blades.

Varmit, do you know who you spoke to at HLA? Daryl would like to follow-up with them on this issue so everyone is on the same page.

Thanks,

CM

 

[varmint]

CM- that's good to know. The valve, a Prince from Surplus Center, was only $70. They had told me the same thing about lightening the release pressure setting at S.C.

I don't want to cause trouble for the tech. I spoke with, so we'll let Daryl sort this out at their next group meeting. They aren't THAT big a company.

If we never get any snow, I will never know about the plow and the valve. I think the cylinder on the 2000 plow may be the same size, which means it should work for me, too? Mine's a 78 blade.

 

[LD1]

It will only work when trying to extend the cylinder. There is no way for it to be effective when trying to compress the cylinder unless they are using a different setup. Possibly a PRV that has its own dump back to tank?

 

[varmint]

LD1- According to the HLA on-line manual, there's no special set up... hoses from tractor plumb into the x-over valve, which then is connected to the cylinder with two hoses. Same cylinder on the 2000 series as on my 1000- 2 1/2 x 8. I may see if there's a way to test it after I reduce the crossover pressure point some.

 

[PILOON]

Hey folks.
A crossover valve ONLY protects the extended corner of the blade.
You hit a curb and the oil dumps over to the other side, but who plows snow away from the curb to the center of the street?
We plow to the ditch side (right side) and when doing so the right corner is retracted so the crossover offers no protection.
It ONLY protects the extended plow corner and when is there a curb in the middle of the street (or the drive)?
OK, so your drive has lots of roots or rocks in the middle so then a crossover can serve you.
On a truck plow at 30-40 MPG a crossover will be an asset but on out slow tractors I am of the opinion that the $$ is better invested elsewhere.
Rely instead on a good trip mechanism with well adjusted trip springs.