Double Pilot Operated Check Valve for 2 Cylinders???

[SkunkWerX]

Can it work?

I am looking at a circuit using two parallel cylinders that will be used to set a given depth/height, but allow for adjustment hydraulically. I want to use a single Double Pilot Operated Lock/Check Valve for both cylinders, since they are to be parallel and balanced.

Using one of these:
Surplus Center Item Detail

Here is what the basic circuit would look like:
(Given that Lengths A and B are Equal lengths AND cylinders have same weight/work to do, in otherwords, the load is balanced between both).

Does this look reasonable? workable? Any inherant design problems?

Thanks, in advance, for your thoughts.

.

 

[kennyd]

Yes that will work BUT if one cylinders has leaky piston seal's then they will both drift.

That is some fancy drawing!

 

[SkunkWerX]

Thanks Kenny. Makes sense about the leaky seal scenario.

This may be the beginning of my Tiller's "Depth-o-Matic" hydraulically adjusted depth thinga-ma-jiggy.

Instead of stopping, and using a set of wrenches for a height/depth adjustment (via the skids), it will be as easy as actuating the cylinders.
Add in to the equation some kind of indexing rod, with inch marks, and it should be easy to adjust from 2", to 4" to 6" etc. without leaving the seat.

Just in the "wild-idea" stage right now.

 

[kennyd]

Just in the "wild-idea" stage right now.

Yeah Right! I've got your number You probably already purchased the stuff and have the mounts welded on the tiller by know!

Just bustin' chops...glad to help.

 

[3RRL]

Skunk,
So this is the idea you posted in the Brush Hog thread.
Pretty good idea.

As long as there are equal pressures against the cylinders, it should work no problem. I have my dual bucket grapple cylinders in parallel but they see different pressures once they hit the object. So one keeps going until it hits home too, but that's what I wanted them to do.
How hard is it to make sure the pressures will be the same? Will you have a connecting bar of some sort to help distribute the load equally? Kind of like an fel bucket? Or is that even necessary?

I used that exact same lock valve from Surplus Center and they are very good. As I recall, they have a cracking pressure of 1/4 or something like that. I'm anxious to see what you come up with. It looks extremely interesting.
And very nice drawings too!

 

[SkunkWerX]

Skunk,
So this is the idea you posted in the Brush Hog thread.
Pretty good idea.

As long as there are equal pressures against the cylinders, it should work no problem. I have my dual bucket grapple cylinders in parallel but they see different pressures once they hit the object. So one keeps going until it hits home too, but that's what I wanted them to do.
How hard is it to make sure the pressures will be the same? Will you have a connecting bar of some sort to help distribute the load equally? Kind of like an fel bucket? Or is that even necessary?

I used that exact same lock valve from Surplus Center and they are very good. As I recall, they have a cracking pressure of 1/4 or something like that. I'm anxious to see what you come up with. It looks extremely interesting.
And very nice drawings too!

Rob, yes, but actually after I posted my reply to your question, I kept pondering and this is what I came up with. Your Wheel assembly would work well, but they would trail behind in the freshly tilled soil, that was the rub.

I agree, with the equal pressure idea, which is why I emphasized that I'd make all hose lengths equal, on the downstream side of the Pilot valve.
Good to hear someone has used that valve and it works.
Might even be able to get away without it, but, since it's a Depth adjuster, better to make it more of an absolute adjustment.

Kenny, Man, I wish I was that quick!!

Next step will be check for possible mount points on the tiller frame (upper) and skids (lower). I'm looking at cylinders, probably 8" stroke.
I"m only lifting the weight of the tiller, which is 500#. Trying to find something smaller than a 2" cylinder. Seems like [2] 2" cylinders is a bit overkill? I don't mind overbuilding, but a small diameter cylinder is gonig to give me a better fit & finish by keeping the cylinders clsoe to the tiller body on each side.

thanks guys!

 

[john_bud]

Wouldn't it be easier to just use 1 cylinder that pushes a lever attached to a bar going to each end? Then you don't have to worry about leaks between cylinders or equalization of pressures.

jb

 

[MJPetersen]

Wouldn't it be easier to just use 1 cylinder that pushes a lever attached to a bar going to each end? Then you don't have to worry about leaks between cylinders or equalization of pressures. jb

Yes I agree. I would thing that you could have one cylinder rotate a shaft that was connected on the ends to your draft depth wheels. The cylinder would not have to be in the middle, just anywhere along the length of the shaft.

The thing about hyd is that you do not need to have equal length hose--the pressure will be the same any place that you measure it in the blue side and anywhere you measure on the red side. A fluid, because it is not compressible transmits pressure to all parts equally. Think of loader arms. the hose usually runs down the right side and "T"s off to the right lift cylinder then continues clear around to the second cyl. That is about as unequal length as you can get, but both lift together.

This is a very cool idea though. I like it.

Mike

 

[SkunkWerX]

Wouldn't it be easier to just use 1 cylinder that pushes a lever attached to a bar going to each end? Then you don't have to worry about leaks between cylinders or equalization of pressures.

jb

JohnB,
I agree, that would be the most direct approach.

I'm still looking it over, but, getting clearance from all the various parts on top of the tiller is easier said than done. 2 cylinders is double overkill, and double costly too. it would be nice to save the cost of the 2nd cylinder, I'm not as concerned about equalizing pressures, etc.

I'm looking in the area of the 3 PH "A" frame, but have to be careful not to interfere with the PTO, Lower arms, and toplink. on the top area, there is the gearbox, horizontal shaft, etc.

I may be able to offset a single cylinder on the top, and just use a beefy lever and bar, like you said, or rotating a shaft with linkages going to each skid, as MJP suggested.

It's a quagmire, at the moment, just looking for a clean enough area to mount anything.

My other fleeting thought would be use a 12v linear actuator, but the same clearance issues are there as with a hyd. cylinder.

JohnB and MJP, Thanks for the thoughts, much appreciated.

 

[SkunkWerX]

Hooked up the tiller brought it int othe shop.

I cannot find a good place, for not only a single cylinder, but the rotating shaft. There is too much in the way on top of the tiller, so, I don't think the single cylinder idea is gonig to work...but, thanks, it was a very good idea and would have saved the cost of s second cylinder.

I guess I am back to a dual cylinder set-up.

Need to find a pair of skinny 8" stroke cylinders.
2" cylinders are going to overkill from a power perspective, but, I'd rather cut the bulk down for some slimmer cylinders.

At the Max. it's lifting about 500# (weight of the unit=550#) and probably much less, since it's pivoting on the front bolt giving some leverage.

Need 2 small cylinders...anyone? any ideas?

1.5" x 8" stroke would probably be a good start.