geometry for a 90 degree tilt cylinder

[bdog]

I need to put a hydraulic cylinder on a piece of equipment to tilt something from vertical to horizontal for transport. The piece being tilted is about 15' tall and weighs maybe 1500 lb. No loads on it other than itself. The pivot point is close to the middle - about 6-7' feet off the ground.

I am not really sure what size of cylinder I need in terms of diameter , length, travel, and how I should mount it as far as angles, distance from the pivot point, etc.

My only idea was to mark two points one on the frame of stationary piece and one on the moving piece and measure the distances between them in the vertical and horizontal positions. This will tell me the length and travel I need but I am unsure how to best pick these two points specifically their positions relative to the pivot point.


Any advice?

 

[J_J]

The most force you will have is when the cyl is pushing straight on.

At any other angle, you will push with less force.

So it depends on the load you need to move, as to what size cyl to use.

Where you place the push/pull point depends on the distance you want the item to move.

The closed you mount the cyl to the pivot point, the faster the tilt will move.

For example.

2 in cyl

1 in bore

3000 psi

push force 9,425 lbs

pull force 7,069 lbs

3 in cyl

1.5 in bore

3000 psi

push force 21,206 lbs

pull force 15,904 lbs

 

[muddstopper]

When you say the pivot point is close to the middle, are your refering to the object bing lifted, or is that 6 or 7 ft is hosw high the piece is mounted off the ground. For angles, you can use the old A sq +B sq = C sq for measureing triangles. . The distance from the fixed attachment point of the cylinder measured to the mounting point of the opposite end of cylinder would be one side of the triangle, (A). The pivot point of the piece being moved to the attaching point of the cylinder on the moveable piece being another side of triangle. (B). The distance the part moves being the third side of the triangle. (C)

I probably just confused you more than you already was, maybe someone else can help clarify what I said.

 

[bdog]

Both. The object to be tilted is 15 feet tall and is normally vertical. The pivot point is 7 feet off the ground so it is close to the middle of the object being tilted and is mounted 7 feet of the ground on the stationary object.

I get the the a sq + b sq = c sq but I don't think I really need or even want right triangles here. I have attached a crude drawing of what I am trying to do. The black outline is the stationary piece. The cylinder has to be mounted on top of it. The red is the object that will tilt, and the green is the approximate cylinder location.

If I could mount the left end of the cylinder lower than the pivot point I think it would be easier to figure out but I can't. It has to be mounted on top like shown. This means the cylinder will almost be parallel with the mast when it is in the horizontal position.

 

[bdog]

The most force you will have is when the cyl is pushing straight on.

At any other angle, you will push with less force.

So it depends on the load you need to move, as to what size cyl to use.

Where you place the push/pull point depends on the distance you want the item to move.

The closed you mount the cyl to the pivot point, the faster the tilt will move.

For example.

2 in cyl

1 in bore

3000 psi

push force 9,425 lbs

pull force 7,069 lbs

3 in cyl

1.5 in bore

3000 psi

push force 21,206 lbs

pull force 15,904 lbs

Thanks for the reply. As far as speed of tilt goes I don't think it matters. It is not going to be tilted very often. The force I need is only what is required to tilt this object which weighs about 1500 lb. I will not be lifting anything with it. Also the pivot point is close to the center so I am thinking I don't need a whole lot of force to move it. I think the 2" cylinder with 1" bore would be plenty I just need to figure out the length I need and the angle to mount it.

 

[JohninCT]

Both. The object to be tilted is 15 feet tall and is normally vertical. The pivot point is 7 feet off the ground so it is close to the middle of the object being tilted and is mounted 7 feet of the ground on the stationary object.

I get the the a sq + b sq = c sq but I don't think I really need or even want right triangles here. I have attached a crude drawing of what I am trying to do. The black outline is the stationary piece. The cylinder has to be mounted on top of it. The red is the object that will tilt, and the green is the approximate cylinder location.

If I could mount the left end of the cylinder lower than the pivot point I think it would be easier to figure out but I can't. It has to be mounted on top like shown. This means the cylinder will almost be parallel with the mast when it is in the horizontal position.

With the cylinder needing to be mounted on top like shown my thought is to have the cylinder extended when the object is tilted vertical and have it retract to tilt it horizontal. The part of the cylinder that attaches to the tilting table should be attached to a slider track (think of a bolt riding in a slot cut in a plate).

The slot I think would need to be angled slightly down when viewed in the horizontal position. This will allow the table to begin to raise as the cylinder extends and rides up the slot. Then as the table becomes tilted the cylinder pushes against the back of the table more like what you have shown until fully extended which is when the table is vertical. Retract the cylinder and the slider backs down the angled slot to help start the table tilting toward horizontal.

I think you need a slider in front to keep the cylinder from trying to push the table further horizontal when it starts extending. You need to have a slight angle up on the cylinder when the table is positioned horizontal if you use a rigid front connection. Or you can use the angled slot slider as described to allow the cylinder to lay down a little flatter.

 

[muddstopper]

Your drawing makes it a lot more clearer. Is the piece being tilted going to lay flat on top , or just lean toward the cylinder. It seems to me your geometry the way it is drawn, that the lifted piece will pretty much be balanced and not need much force. You are still working with a triangle, even tho it doesnt have to be right angle. In the upright position you will have a 90degree right angle from the possible mounting point to the pivot point. Your cylinder wont have to be all that long to accomplish what you have drawn, even if the lifted part will lay horizontal in the upright position. to determine distance and angle, you will need to have some set measurement to start. This measurement will most likely be the retracted lenght of your cylinder or side A of the triangle. The extended lenght of your cylinder will most likely be the C side of your triangle. Stroke of cyl will form the B side of the triangle. How far you want the boom to retract in the down position will determine where you need to put the mounting point, but those mounting points must equal the full extended lenght of the cylinder.

A 12in stroke cyl from surplus center has a retracted lenght of 22 1/4inches. Add the stroke and you have a total of 34 1/4 inches. You can use the 22 1/4 as the A side, the 12in as the Bside, and the 34 1/4 as the C side of your triangle and this should allow you to lower the lift from 90degree vertical to 0 degree horizontal. All measurements taken from center of pivot point.

Edited to add: The mounting point for the base of the cylinder should also take into account the length of side A Plus the length of side B. Since the angle changes as the lift goes from horizontal to vertical as will the length of C side as the cyl is extended/retracted. This would mean that you would add the 22 1/4 in retracted cyl lenght to the 12 in cyl stroke for a total of 34 1/4 in. The effect would be that the mounting point for the base of the cylinder would be 34 1/4 in from the pivot point which is the same as the extended length of the cylinder, since when laying flat you would have the retracted length of the cylinder in addition to the mounting point length on the piece being lifted. A side and C side would be equal length, and the B side would be 12in. The A and B sides would remain fixed lengths while the Cside length would change as the cyl is being extended and retracted.

Now if you dont need the lifted part to lay horizontal, you can move the mounting point of the base of the cylinder closer to the pivot point of the lifted piece, but for every inch you move the base mount closer to pivot, you will also need to move the rod mount further from pivot. Faliure to move the rod end mount further from pivot will result in lifted piece going past vertical or 90degrees.

 

[npalen]

The distance from the center of gravity of the object to be tilted to the pivot point has some importance. The effort required to rotate the object would be zero if the distance is zero as it would obviously be balanced. Is the "object" of fairly uniform cross section? Will the "object" be identified at some point in this discussion?