Popular mythconceptions

[4570Man]

In a push-pull use of a cylinder one direction is stronger, but it will make no difference if the cylinder is turned around. Orientation still doesn't matter.

Bruce

Obviously the cylinder would be stronger with the rod up because then it’s not having to lift the weight of the body and fluid. Insert sarcasm here. The much more important thing to do is position the cylinder so the hoses aren’t moving and chafing them.

 

[MossRoad]

No conditions. Doesn't matter which end the rod is on when it is mounted on an implement. It extends or retracts with the same strength no matter which direction it is mounted.

View attachment 612670

Yes, extension is always stronger than retraction, but we are not talking about that.

Bruce

If you'd have put an 's' on the word 'strength' we'd all be happy.

 

[goeduck]

I'm going to bed now.

Myth or will there be a conception? :laughing:

 

[4570Man]

I used to be in this camp but another one is a cylinder can retract without loosing oil out of it. Common misconception is that leaking piston seals wound make a cylinder leak down. It could make it happen faster but it CANNOT be the sole cause.

 

[goeduck]

Obviously the cylinder would be stronger with the rod up because then it’s not having to lift the weight of the body and fluid. Insert sarcasm here. The much more important thing to do is position the cylinder so the hoses aren’t moving and chafing them.

Cylinders are stronger with the rod up and the rod is extended prior to conception. No myth ! :rotfl:

 

[bcp]

If you'd have put an 's' on the word 'strength' we'd all be happy.

That probably would have helped.

Think of a horizontal cylinder opening and closing a door. Whether the rod end is on the door or on the frame, the force the extending cylinder exerts to open the door is the same. The retracting, door closing force is less, but whether the rod end is on the door or the frame, the retraction, closing force is the same. The opening-closing, extension-retraction forces are not the same because of the rod area subtracted from the piston area. But the cylinder orientation does not change these forces.

Bruce

 

[dstig1]

No conditions. Doesn't matter which end the rod is on when it is mounted on an implement. It extends or retracts with the same strength no matter which direction it is mounted.

View attachment 612670

Yes, extension is always stronger than retraction, but we are not talking about that.

Bruce

I'm not sure why I am going to wade into this argument, but here I am...

There are 2 different force numbers for the force a hydraulic cylinder can generate depending on if it is in extension or retraction. This is shown in the numbers on the Hyd cyl spec sheet. The reason is simple - You assume the Hyd pressure is a constant in both extension and retraction. The formula for force in this case is pressure*area = force On extension, the full internal diameter of the cylinder is available as the area that the hydraulic fluid acts upon. In retraction, you must subtract the rod area from the cyl ID area to get the area acted upon by the fluid. Therefore it will be less than on extension. Force extension > force retraction, with the same fluid pressure.

Are you saying something different?

 

[4570Man]

You guys still aren’t understanding the scenario. Pretty much everyone understands that a cylinder is weaker in retraction vs extension. BUT the cylinder is extending for both test. The only difference is it’s standing barrel up vs barrel down.

 

[bcp]

I'm not sure why I am going to wade into this argument, but here I am...

There are 2 different force numbers for the force a hydraulic cylinder can generate depending on if it is in extension or retraction. This is shown in the numbers on the Hyd cyl spec sheet. The reason is simple - You assume the Hyd pressure is a constant in both extension and retraction. The formula for force in this case is pressure*area = force On extension, the full internal diameter of the cylinder is available as the area that the hydraulic fluid acts upon. In retraction, you must subtract the rod area from the cyl ID area to get the area acted upon by the fluid. Therefore it will be less than on extension. Force extension > force retraction, with the same fluid pressure.

Are you saying something different?

I'm saying exactly the same. But the myth is that dismounting a cylinder, turning it around, and remounting it will cause the stronger and weaker forces to change direction.

I've heard this kind of statement many times, but it is wrong. "That's a nice dump trailer you made. But if you turned that cylinder around it would lift more."

Bruce

 

[MossRoad]

That probably would have helped.

Think of a horizontal cylinder opening and closing a door. Whether the rod end is on the door or on the frame, the force the extending cylinder exerts to open the door is the same. The retracting, door closing force is less, but whether the rod end is on the door or the frame, the retraction, closing force is the same. The opening-closing, extension-retraction forces are not the same because of the rod area subtracted from the piston area. But the cylinder orientation does not change these forces.

Bruce

yep! :thumbsup: