Cylinder Within A Cylinder?

[npalen]

https://www.alamo-industrial.com/Pr...pring_brk-away_parts_manual__11-06__03-18.pdf

Page 20 in this parts book shows a cylinder design that I don't recall seeing ever. I assume the idea is to get additional force within a confined space.
Have you seen anything like it?

 

[RNeumann]

This is what I’m used to seeing.....

Telescopic Ram TR 535 LP | Holmatro

 

[bcp]

Telescoping cylinder. Extended length can be much longer than retracted length, compared to a simple cylinder.

Telescopic cylinder - Wikipedia

telescoping hydraulic cylinder images

Bruce

 

[BrokenTrack]

I think they are great for extension, but lack strength. That is because there is less surface are to act upon as the hydraulics push on the various stages of ram.

But they have been on dump trucks for years.

You can order them on Surplus Center, but get kind of expensive.

 

[RickB]

I think they are great for extension, but lack strength. That is because there is less surface are to act upon as the hydraulics push on the various stages of ram.

But they have been on dump trucks for years.

You can order them on Surplus Center, but get kind of expensive.

Generally the applications where telescoping cylinders are used require more lift at the beginning of the stroke (dump bodies). In other cases the design advantage of short retracted length outweighs the design requirement that the maximum force required be met by the smallest diameter stage. They are not weak when properly engineered.

 

[npalen]

I don't think the cylinder shown on page 20 (see post #1) is a telescopic cylinder. The snap ring shown as item 13 would stop the extension of both the outer and inner pistons and there wouldn't be another stage(s) as in a telescopic cylinder. It appears that the double piston simply adds additional force rather than travel length. It's a bit perplexing to study as it's not what it first appears to be.

The item 5 would appear at first glance to be a rod, as we know it, but I'm thinking that all it does is act as a stop to keep the item 3 piston stationary. Notice that the fluid enters thru the clevis on the "rod end" as well as the post at the base end of the cylinder.

I believe it is a single acting cylinder with the two ports connected to the same pressure source.

 

[wdchyd]

I don't think the cylinder shown on page 20 (see post #1) is a telescopic cylinder. The snap ring shown as item 13 would stop the extension of both the outer and inner pistons and there wouldn't be another stage(s) as in a telescopic cylinder. It appears that the double piston simply adds additional force rather than travel length. It's a bit perplexing to study as it's not what it first appears to be.

The item 5 would appear at first glance to be a rod, as we know it, but I'm thinking that all it does is act as a stop to keep the item 3 piston stationary. Notice that the fluid enters thru the clevis on the "rod end" as well as the post at the base end of the cylinder.

I believe it is a single acting cylinder with the two ports connected to the same pressure source.

Yes, retract limiter, adjusted by a separate circuit on the control valve

 

[MossRoad]

The parts diagram lists
5 - rod
4 - rod weldmt
3 - piston
1 - tube weldmt

It sure looks like a tube within a tube... never seen one before :confused3:

 

[4570Man]

I think they are great for extension, but lack strength. That is because there is less surface are to act upon as the hydraulics push on the various stages of ram.

But they have been on dump trucks for years.

You can order them on Surplus Center, but get kind of expensive.

They have full strength at the bottom and each step is weaker. A dump truck gets easier to lift the higher up it goes.

 

[npalen]

Yes, retract limiter, adjusted by a separate circuit on the control valve

Retract limiter! Of course! You nailed it. I can see that now and thanks otherwise it may have kept me up all night.