Balancing tandem cylinders?

[DiskDoctr]

How do you tie two smaller cylinders together, one one each end of a pivot bar, so they stay synchronized and balanced?

I want to provide more force than one cylinder provides, so I am thinking how to connect 2 cylinders to the same push mechanism.

Think a powerful and fast splitter or press with two cylinders that must push and pull in a perfectly balanced speed. They would be matched cylinders of the exact same size, model and type.

I have various cylinders and such available. No sense buying a large, expensive cylinder if I can use two smaller ones I may have around

Any ideas?

- JC

 

[glastron23]

the problem is #1 how accurate do you have to be #2 now much money don't you want to spend????
for #1 try this Divider, Flow, 2.4-5 GPM - Hydraulic Flow Dividers - Hydraulic System Components - 4F660 : Grainger Industrial Supply
for #2 try this HydraForce Hydraulic Flow Control Cartridge Valves
Jim

 

[tshep]

"one one each end of a pivot bar" and "splitter or press with two cylinders that must push and pull in a perfectly balanced speed" sound like 2 different things.

Each end of a pivot sounds like opposite travel and press sounds like same travel.

For simple press, I think they could just be plumbed in parallel.
That's how my FEL lift arms are - the mount/mechanism kinda' makes up for any temporary differences. I would think mounting both on a single extra long bolt (each end) would just double the force area and any difference between the 2 would quickly average out through the circuit flows.

 

[glastron23]

just what are you trying to do here?? just pushing on a splitter plate or trying to push 2 cylinders to lift a boom.

 

[mrmikey]

Don't know what type of application you're trying to design but there's another alternative, depending on how much money you want to spend.
See if you can find two cylinders that the volume on the rod end of one equals the volume of the barrell end of the other. After the rod end of one and barrell end of the other cylinder is filled with oil they're connected with hydraulic hose and purged of any air. Then the opposite end of each cylinder is then plumbed, one to each working port of the valve.

This will work as a similar system is used on a side dump salt spreader body to make sure the side went up evenly. Previously a flow divinder was used but going this route is cheaper as they're isn't any extra parts required. There are disadvantages tho, it's imperative to remove all the air as air will compress throwing off the syncing of the stroke. Also it's a pain to fill up without getting air in the system.

Afried of mine has the same setup on a bend brake he had built to make sure the blade moved evenly without going into the expense of fancy hydraulic valves.....Mike

 

[Brad_Blazer]

2 identical cylinders plumbed in parallel will put out the same force. The mechanism just needs a little rigidity to keep them synchronized. Almost every loader uses this setup.

 

[DiskDoctr]

I'm thinking about for the log splitter of a firewood processor. 40-60 ton.

Picture a triangle shape with a pin on each point. One cylinder is attached to each of 2 points, with the flat side of the triangle going between the cylinders and the other point faces away from the cylinders and attaches to the push plate of the splitter.

I was thinking about using two smaller cylinders, combining through this mount to push the splitter plate with a combined force. Balancing them would be to prevent binding and uneven pushing.

The balancing wouldn't have to be incredibly accurate, just enough to prevent binding

- JC

 

[glastron23]

Diskdoc.. if you are going to attach the base of the cylinders to a common point and the rod ends to a common point then synchronization is not all that important. The hydraulics will level themselves out. Jim

 

[SSdoxie]

Years ago, when I first started seeing hydraulic wood splitters becoming more popular, many were made this way with 2 smaller cylinders versus 1 larger one. Secure both base end and rod end to the same fixed attaching points and plumb cylinders in parralel. Either mount them side by side or one on top of the other. Stacking them veritically, on top of each other, would allow having a taller push block and reduce binding of the block on the slide.

 

[J_J]

If you were to disconnect the rod ends off your loader arms, and cause the cyl to extend, one of the cyl may lag somewhat because of seals, or is just tighter, that would be normal. They both will finally push out to max.

There are balance circuits for cyls that read the pressure , and other things like cyl position, etc. If the cyl ends are connected to the same ref plate, and rod end is pushing on the same reference wedge /plate, the force should double with the same resistance.

One way to determine that, would be to put a gage on each cyl base end port, and push against something solid. This is assuming that the cyls are equal. If they are not equal, as in one cyl is leaking internally, then that cyl will show less pressure, but the force will add up with whatever pressure is available.

If the forces does not add up, to be twice the single rated force, that tells you that one cyl is better than the other.

Just tee in two gages to test this theory.

This is also a good way to match up a pair of cyl.