Does this make sense? Trailer tilt methods....

[Rx7man]

Here's a link to a trailer manufacturer, and their claims of which style of lift/tilt system is best on a trailer...
http://bigtextrailers.com/hoist-comparison/

I have a very hard time seeing how the 2 ram system is inferior to the single ram system especially.. assuming build quality is equal in all styles.

 

[phinds]

Here's a link to a trailer manufacturer, and their claims of which style of lift/tilt system is best on a trailer...
http://bigtextrailers.com/hoist-comparison/

I have a very hard time seeing how the 2 ram system is inferior to the single ram system especially.. assuming build quality is equal in all styles.

So you don't believe their statement " If one hoist were to ever get out of rhythm with the other, it could cause catastrophic frame twist and major damage"

 

[Baluncore]

One ram is simple and works. Two rams clearly have a harmonising requirement, with potentially destructive results. The scissor technique is not shown with sufficient clarity to be analysed. I suspect BigTex marketing believe you need more faith in the brand, with less engineering analysis.

A tipper ram needs to be short to avoid bending, so it needs to be moved towards the rear tilt hinge. The two ram solution is needed only when there is no central frame structure and so two tilt rams are used to apply forces close to the axle suspension points on a rectangular trailer base frame. A wide scissor mechanism can substitute for the two ram system, but it requires two heavier torque tubes across the trailer.

Fundamentally, trailer tilting is a difficult problem. The mechanism lies flat below the trailer bed until needed. Then maximum vertical lift force is needed at the start of the lift when the ram lies horizontal. At the end of the process, with 90° tilt, the minimum force is needed. Some mechanism must turn that relationship around, or the ram will need to be heavier and the trailer frame stronger and so heavier.

The first requirement is that the tilt mechanism does the job of meeting specifications safely. The second requirement is that the total weight of the trailer including the mechanism be reduced. There are many possible solutions.

Tipping is the biggest problem. There are better solutions for tilt trays and slide trays. Take a deeper look at the mechanisms that tilt truck trays and other trailers. Also look at the linkage that curls the bucket at the end of a backhoe dipper arm.

 

[Ranger Mike]

The only way I see you may have a "Harmonic" problem is ifin you got two hydraulic pumps operating, one per cylinder. I doubt this is the case. Since you most likely have one hydraulic pump and two hoses running to the rams, the pressure is going to be the same for both. The only time you will run into a twist and stress situation is if one ram has a blown seal or if one pivot hinge gets jammed with debris or something. My opinion is the advertisement is typical fear mongering to swing you to purchase their product. You got the same required pressure to lift the load but spread it out over two rams vs one bigger ram. Longer life span...my opinion..remember, opinions are free and carry the same value

 

[Rx7man]

Our little farm dump trailer has a single, 3 stage vertical lift cylinder (like regular dump trucks), and that thing is incredibly strong.
I can still see the mount, and half of what's left of a scissor lift system on it.

I certainly don't see any "harmonic" problems, that just sounds like they're using words they don't know to sound fancy.
The only problem I could see is if one side of the trailer was loaded more than the other and it would twist, but having a single cylinder in the middle isn't going to help that, and the scissor system, being quite narrow isn't going to prevent that.
One benefit I see to the scissor system is that the forces on the hinge pins have no horizontal component, the scissor extends and pushes straight upward, while the single and twin ram systems, especially at low lift, exert more horizontal force than vertical force.

If you wanted to get fancy, there are flow dividers for hydraulic systems specifically designed for these applications, to force the two cylinders to extend the same amount regardless of the load that's on them.

Our hay wagon, which has stacked thousands of stacks of hay uses the twin ram system.. 40 years later it is still working perfectly (at least that part of it).

 

[OCR]

Our hay wagon, which has stacked thousands of stacks of hay uses the twin ram system..

If your "hay wagon" was actually a John Deere stack wagon, it did use two cylinders, one on each side... however, they were arranged in a master-slave configuration.

The right side cylinders (rod) ram end output oil was plumbed into the left side cylinders piston input oil end... this arrangement kept both cylinders ram extension travel synchronized.

The left cylinders diameter was actually a bit smaller than the right ... this was necessary to compensate for the right cylinders ram displacement.Lol... I made hay "loafs" from about 400 acres of alfalfa, every year, for about 20 years with that system... I did a lot of fix'n on it too...

Our hay wagon...

I'm under the assumption... you mean this ?

 

[Rx7man]

If your "hay wagon" was actually a John Deere stack wagon, it did use two cylinders, one on each side... however, they were arranged in a master-slave configuration.

The right side cylinders (rod) ram end output oil was plumbed into the left side cylinders piston input oil end... this arrangement kept both cylinders ram extension travel synchronized.

The left cylinders diameter was actually a bit smaller than the right ... this was necessary to compensate for the right cylinders ram displacement.Lol... I made hay "loafs" from about 400 acres of alfalfa, every year, for about 20 years with that system... I did a lot of fix'n on it too...

I'm under the assumption... you mean this ?

Nope, this one
If I were to be as fussy about perfect stacking I'd never get anything done... I'm in and out of the shed in under a minute, with the hydraulics being my limiting factor

 

[CWatters]

Since you most likely have one hydraulic pump and two hoses running to the rams, the pressure is going to be the same for both.

It's not the pressure you want to be the same it's the flow rate. Consider what happens if the load is on one side.

 

[Rx7man]

There are splitter valves designed to prevent that.. Found this which describes how they work
https://www.mathworks.com/help/physmod/hydro/ref/flowdivider.html?requestedDomain=www.mathworks.com

There are lots of different designs, radial piston, gear, etc
http://www.directindustry.com/industrial-manufacturer/flow-divider-75289.html

 

[Averagesupernova]

It's not the pressure you want to be the same it's the flow rate. Consider what happens if the load is on one side.

Except when it is stationary. If the cylinders are simply plumbed in parallel and not phased, the pressure will be the same in both cylinders.

 

[OCR]

Nope, this one...

Ah...
We always just called them... https://www.machinerypete.com/details/bale-wagons-and-trailers/new-holland/1032/19176849 ...

I take it you've bent your pushoff feet, before, too... eh ? .. lol

 

[Baluncore]

I have a very hard time seeing how the 2 ram system is inferior to the single ram system especially.. assuming build quality is equal in all styles.

Does that mean a three ram system would be better again?

 

[Averagesupernova]

Does that mean a three ram system would be better again?

Until we establish the real reason why one company uses two cylinders instead of one, and vice versa, as well as how they are plumbed that really isn't a valid question.

 

[Baluncore]

Until we establish the real reason why one company uses two cylinders instead of one, and vice versa, as well as how they are plumbed that really isn't a valid question.

How can there be a "real reason" applied to all trailers of all designs? Who made you the censor, no question on PF is invalid.
That question is related to the state of Rx7man's thought processes. I consider it is needed to refine the OP.
Is this thread discussing special purpose agricultural / industrial trailers, or road-legal trailers where weight becomes critical to vehicle design and economy?

 

[OCR]

That question is related to the state of Rx7man's thought processes.

OMG ... not that ! .

 

[Averagesupernova]

How can there be a "real reason" applied to all trailers of all designs? Who made you the censor, no question on PF is invalid.
That question is related to the state of Rx7man's thought processes. I consider it is needed to refine the OP.
Is this thread discussing special purpose agricultural / industrial trailers, or road-legal trailers where weight becomes critical to vehicle design and economy?

You more or less prove my point. The original point was to conclude that the notion of: "Two cylinders always bad! One cylinder always good!" is a bunch of rubbish. I'd say we have succeeded in this. Anything beyond this needs more specifics to be worthwhile to discuss. To simply state that if someone thinks 2 cylinders are as good as one, then 3 should be acceptable is silly. Why stop at 3? What's wrong with 4, 5, 6...

 

[Rx7man]

Ah...
We always just called them... https://www.machinerypete.com/details/bale-wagons-and-trailers/new-holland/1032/19176849 ...

I take it you've bent your pushoff feet, before, too... eh ? .. lol

My dad did.. that's not our bale wagon, just a video I found of the same model... Ours is in MUCH worse condition, but still works alright.

How can there be a "real reason" applied to all trailers of all designs? Who made you the censor, no question on PF is invalid.
That question is related to the state of Rx7man's thought processes. I consider it is needed to refine the OP.
Is this thread discussing special purpose agricultural / industrial trailers, or road-legal trailers where weight becomes critical to vehicle design and economy?

I asked the question because a lot of companies are good at hyping up their version of a system, and vilifying other sytems... regardless of whether it is indeed better. All systems will fail if the deck of the trailer is flimsy.

To me, when I look at the physics of how they work, all 3 designs shown suffer of the same fundamental flaw, you need a far heavier cylinder because of the mechanical disadvantage they have when the deck is flat, and conversely, have peak lifting ability around max tilt, when in all likelihood you really don't need much force at all (everything has slid off already)
It's not convenient to have such a cylinder mounted on a small trailer, but there must be a reason that every large dumptruck uses a multistage, single lift cylinder!

 

[Averagesupernova]

Multistage cylinders in dump trucks have the largest piston area when they just start to lift which is also when they need to exert the most force compared to when the box is halfway up. They aren't all singles. There are doubles out there.

 

[OCR]

... I saw your comment.

that's not our bale wagon, just a video I found of the same model...

 

[Rx7man]

Multistage cylinders in dump trucks have the largest piston area when they just start to lift which is also when they need to exert the most force compared to when the box is halfway up. They aren't all singles. There are doubles out there.

True.. When looking at heavy equipment, about the only system you don't see is the scissor lift!

If two is bad, and one is good, none must be best!

 

[Baluncore]

If two is bad, and one is good, none must be best!

Correct. KISS.