Snow plow fabrication

[GPintheMitten]

You're welcome.

 

[ovrszd]

How is that not the perfect setup?

I much prefer a pair of sa cylinders as opposed to one da.

Equal forces, equal speeds, and equal volumes of fluid means you can use a simple crossover relief for protection

Excuse my redneck thoughts on this. I look at it as imperfect because there is only one cylinder working against the forces of the blade at one time. For example, if I have the blade angled to the right. The left cylinder is pushing forward on the blade. The right cylinder has no pressure preventing any action other than compression. So if a force pushes rearward on the left end of the blade, the only thing preventing it is the strength of the left cylinder. The right one is just along for the ride. If the left one fails, all the right one has to offer is vacuum???

On the other hand if you have two DA cylinders each, by design, is holding itself in position with hydraulic pressure??

I see this when using my blade. When enough force is applied it acts like it has air in the system. Blade is allowed to move a small amount. Not saying this is a horrible, doomed to failure setup. Just saying it's not as strong as two DA cylinders.

Again, I'm not very hydraulic smart so am open to debate.

 

[LD1]

A DA cylinder will offer no more resistance to extension as it will just suck air in through the gland seal.

Only thing a pair of DA cylinders offer is greater angling force if the cylinders are the same size. You gain the pull force of the second cylinder.

And the theory about if one fails....well if that happens you have other things to worry about than a squishy feeling blade.

It is uncommon to see a pair of DA cylinders anyway. Usually it's either a pair of SA or a single DA. The single DA is the inferior setup

 

[ovrszd]

A DA cylinder will offer no more resistance to extension as it will just suck air in through the gland seal.

Only thing a pair of DA cylinders offer is greater angling force if the cylinders are the same size. You gain the pull force of the second cylinder.

And the theory about if one fails....well if that happens you have other things to worry about than a squishy feeling blade.

It is uncommon to see a pair of DA cylinders anyway. Usually it's either a pair of SA or a single DA. The single DA is the inferior setup

Good stuff. I think what I was referring to is described in your statement of "You gain the pull force of the second cylinder".

 

[Rustyiron]

My Fisher "V" has 2 d/a cyls. Necessary for independ l/r "wing" movement.

 

[LD1]

My Fisher "V" has 2 d/a cyls. Necessary for independ l/r "wing" movement.

That's the best way to do a vee IMO. But not necessary. Some still use SA cylinders and a spring for return

 

[Rustyiron]

Just saying it's not as strong as two DA cylinders.

For sure Richard, but there needs to be a little "give" in the system. You're not in that beast of a road grader you run around in:laughing:

 

[Glrret]

The type cylinders I have on my old plow truck are SA. I plan to use the same type cylinders on the tractor plow.

 

[PILOON]

Also, how would you install a crossover valve on DA system, I believe they would only work on single action pairs.
Mind you even with a crossover valve only the extended corner is protected.
The retracted corner is already retracted so it can not further retract.
The only time that crossover protects is if you are pushing snow away from a curb and hit that curb, usually you are pushing towards the curb.

Still the best blade protection is either a trip edge or optionally a blade that tilts (dumps).

The tilting/dumping blade is the easier to fabricate. (I built my own)
Also the tilting blade can be fine tuned by adjusting spring tension.

 

[LD1]

Crossover is designed to protect the hydraulics, not the blade. So yea, trip springs are still required.

Crossover will work with a PAIR of DA cylinders. Just not a single