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Just wondering how you figure out what is the best angle for a cylinder to lift from when building equipment?

Or is it a matter of it is either strong enough to lift the weight or not? Doubtful thats the way to look at it!

The tire is set at 3" off floor to give the spring tooth harrows in front the correct depth in the ground - is that too much of a horizontal angle to lift from?

Frame is 3"x3"x3/16" wall.  7'x4' plus the 2"x3" brace for tongue up top.  Will have set of rolling baskets hanging off back as well.

 

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I would add a tube close to the pivot for the axle lifting fulcrum like this. Tack in place then raise and lower to confirm clearance before finishing welding

Just make sure the angle isn't so sharp that it binds on the cylinder clevis and bends or break the rod.

Rephasing cylinders or solid rockshaft, especially if a "middle" position between full up and down is used......otherwise it will settle to the heaviest side part way up.

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Angle of it will effect the strength needed and how high it does or doesn't lift . If it lifts it 16" up it would have half the power as if it was 8" lift 

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Just make sure the angle isn't so sharp that it binds on the cylinder clevis and bends or break the rod.

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1 hour ago, cedar farm said:

Just make sure the angle isn't so sharp that it binds on the cylinder clevis and bends or break the rod.

And that the full cylinder travel acts as the stop, not something you have built. Even small hydraulic cylinders are deceptively strong.

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4 minutes ago, yellowrosefarm said:

And that the full cylinder travel acts as the stop, not something you have built. Even small hydraulic cylinders are deceptively strong.

I run the numbers when I build something, with your known pressure and cylinder size on the extend side, and minus minus the rod diameter on the retract side you can figure out exactly what it can put out.  And it goes without saying you can push way more than you can pull in application because of the above.  I started running numbers after I built something and "Got caught with my pants down" so to speak and didn't have enough...............It wasn't the end of the world as luckily I used a common size and could swap it out with one with a larger bore, but had to change hoses, different cylinders, more $$$$, you know, all the good stuff.

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Thank you for the info guys.  Appreciate it.

@Fred B nope this is the back....certainly in its early stages and A LOT more head scratching needed!

20210404_121751.thumb.jpg.106b1a71de26d0ae810dd4e4e3942c4c.jpg

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On the extension stroke, each cylinder would generate approximately 17,000 lbs of force at 2500 psi.  Figuring leverage losses and allowing for a generous safety margin in lift capacity I would assume the two together offer half of what 1 cylinder can do which  would be about 8500 lbs of lifting power which should be plenty.  As far as deciding where to put the mounts, check how things fit with cylinders retracted and extended.  I would allow for some ability to lower the frame farther than you intend to, just because, unless cylinder stops cannot be used.  

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40 minutes ago, Gearclash said:

On the extension stroke, each cylinder would generate approximately 17,000 lbs of force at 2500 psi.  Figuring leverage losses and allowing for a generous safety margin in lift capacity I would assume the two together offer half of what 1 cylinder can do which  would be about 8500 lbs of lifting power which should be plenty.  As far as deciding where to put the mounts, check how things fit with cylinders retracted and extended.  I would allow for some ability to lower the frame farther than you intend to, just because, unless cylinder stops cannot be used.  

I wouldn't assume that at all.  Not saying your reasoning is wrong but there is no reason to assume anything.  What is the angle that the cylinder is angled at from horizontal.

These are approximate based on the angle. I would make sure you are far below these.  I also wouldn't go below 30 deg unless you absolutely have to.

60 deg: you get approx 85% of lift capacity in the vertical plane

45 deg: you get 70% of lift capacity

30 deg: you get 50% of lift capacity

20 deg: you get 33% of lift capacity

 

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I'm sure a competent Hydraulic shop can come up with the proper geometry, there is a formula for it. Mudfly & Gearclash quotes some good "rule of thumbs"..

In my experience, the shallower the angle the greater size needed for the cylinder and the more stresses on the attachment points. The greater the angle, less is required, with less stress, but longer cylinder action needed. And this also takes into account the weight of what you are trying to lift. 3/16 ths material is a bit light but it looks like you don't have a lot of weight to deal with. But to be on the safe side I would at least make the cylinder attachment point of at least 3/8 ths material. 

But then I have a tendency to overbuild everything. - Build once - build right - never worry about it again. Build just enough - rebuild or repair over and over and over again......

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4 minutes ago, N S said:

Mudfly & Gearclash quotes some good "rule of thumbs"..

Those aren't rules of thumb, I used the formula.  Those are rounded percentages for those specific angles.  By my eye the cylinder is in the 25 +/- degree range.  That's why I posted the numbers down that far.

20 hours ago, Mountain Heritage said:

is that too much of a horizontal angle to lift from?

If you have the specific angle I can get you the actual numbers, but again, I would use the rough numbers above and make sure you have more cylinder than you need.  

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Cylinder is on 31 degree angle.

 

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At 31 deg, 50% lift capacity is pretty much dead on at the bottom of the stroke.   Once the geometry changes it will increase.

 

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I like to draw things out on the floor, to get angles, and how it will work. also use scraps of lumber, with a nail for a pivot point.  it'll be seen on it's side. use tape measure for hyd cyl.   also type  in roll-a-cone.  I know it's cheating, but there's no point in reinventing the wheel.

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5 hours ago, Mudfly said:

Those aren't rules of thumb, I used the formula.  Those are rounded percentages for those specific angles.  By my eye the cylinder is in the 25 +/- degree range.  That's why I posted the numbers down that far.

If you have the specific angle I can get you the actual numbers, but again, I would use the rough numbers above and make sure you have more cylinder than you need.  

You're right on, Mudfly. One thing that is being overlooked is the ratio between the trailing arm pin to the lower cylinder mount and the trailing arm pin to the axle centerline. If that ratio is 75%, then your load on the cylinder will increase by one third (4/3 is the inverse of 3/4). If the ratio is 66%, than your load will increase by one half (3/2 is the inverse of 2/3).

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On 4/6/2021 at 4:47 AM, Mountain Heritage said:

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How much more machine is there going to be when all is said and done?

As it sits there, you've got enough lift for 10 times what that thing weighs. Dual 3" cylinders even at the most inefficient angle will toss that thing in the air like a beach ball.

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6 minutes ago, Matt Kirsch said:

How much more machine is there going to be when all is said and done?

As it sits there, you've got enough lift for 10 times what that thing weighs. Dual 3" cylinders even at the most inefficient angle will toss that thing in the air like a beach ball.

Two 5 foot wings and then rolling baskets (single row) on everything.

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10 minutes ago, Mountain Heritage said:

Two 5 foot wings and then rolling baskets (single row) on everything.

I would think it's going to be fine. Double check that it would lift both high enough and get low enough for the job . Calculate worn metal for future workability

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On 4/6/2021 at 9:15 AM, Mudfly said:

These are approximate based on the angle. I would make sure you are far below these.  I also wouldn't go below 30 deg unless you absolutely have to.

60 deg: you get approx 85% of lift capacity in the vertical plane

45 deg: you get 70% of lift capacity

30 deg: you get 50% of lift capacity

20 deg: you get 33% of lift capacity

I wonder how those numbers apply to DOWN pressure?

 Caterpillar changed the position of, and the angle of the blade cylinders on their tractors when they went to the oval track, from what it had been on the flat track machines.

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15 minutes ago, Art From Coleman said:

I wonder how those numbers apply to DOWN pressure?

 Caterpillar changed the position of, and the angle of the blade cylinders on their tractors when they went to the oval track, from what it had been on the flat track machines.

Downpressure percentages would be the same.   
 

I should clarify.  Those are the amount of vertical force that you will get from the cylinder.  Then you have to take into account the geometry of whatever you are pushing.

The OP has the pivot point or fulcrum, then the the force (cylinder), then the tire.  Either side can be considered the load.  Since the tire is relatively close to where the cylinder connects, it’s doesn’t change the force much.  Hence why I said to stay well below those numbers.   If the tire was a lot past the cylinder pin, it would be a different story.

On dozers, the same applies, how far back from the blade do the cylinders act on the push arms?  Move that attachment closer to the blade and you will create more downpressure.
 

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So how do I get more travel distance out of a 8" stroke cylinder?  Working on getting wings to come up vertical from down position.  Can get 45 degree out of them.  Tried this set up and horizontal set up.  Suggestions?

@bitty

@Finney

Anyone else??

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More like this?  Moved base of cylinder closer to frame pivot point and increased the height of other end.  Brought bottom of "triangle" together more.

 

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