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Does anyone know any known applications with a stopping ramp that is acctuated with a cylinder and is self locking in its top position. That means that the force on the ramp doesn't load the cylinder, but is done with proper mechanism. An example: Big pipes (15.000 kg) are rolling down a small slope (cca. 0,5°) and I need to stop and buffer them in the middle of the slope. I want to use a simple ramp that opens up in front of them, but I would like to have the ramp almost self locking in top position so that the cylinder doesn't need to transfer the majority of force, when the pipe hits the ramp.

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    $\begingroup$ by cylinder you mean a hydraulic cylinder? This would be some type of pawl that locks the mechanism at the top of travel (spring loaded stop). You would need a way to pull that stop out prior to retracting. $\endgroup$
    – Tiger Guy
    Aug 27 at 15:02
  • $\begingroup$ Actually I mean pneumatic cylinder, because that is the requirement. $\endgroup$
    – Grega
    Aug 29 at 14:04
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You might be able to do it like this:

(quick sketch, members not to scale)

ramp diagram

When the cylinder is fully extended, the 2 beams will be aligned and the cylinder bears almost no weight.

When the cylinder retracts the rear support formed by the two beams folds, thus lowering the ramp.

Retracted State: retracted state

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  • $\begingroup$ I had this one in mind already, nontheless thanks for the idea. $\endgroup$
    – Grega
    Aug 29 at 14:05
  • $\begingroup$ How the force is prevented to load the hydraulic cylinder? Can you elaborate more on the sequence of operation? $\endgroup$
    – r13
    Aug 29 at 20:45
  • $\begingroup$ @r13 The blue and green lines are rigid members with hinges at the ends. When they are inline, they cannot exert a lateral force on the cylinder no matter how much force is applied along their length. $\endgroup$
    – Drew
    Aug 29 at 21:05
  • $\begingroup$ I added a sketch to show my confusion. Please delete it once you've updated the information. Thanks. $\endgroup$
    – r13
    Aug 29 at 21:26
  • $\begingroup$ @r13, Added diagram of retracted state. In the future please do not modify an answer in a way that doesn't actually improve it. Asking for an additional diagram in the comments would be sufficient. $\endgroup$
    – Drew
    Aug 29 at 22:19
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Here is an idea if you want the ramp to lock in a fixed position after raising by hydraulic jacks (attached to the ramp framing). As shown, once the ramp frame has cleared the latch, the latch will be in the desired position to support the ramp frame until manually re-positioned.

Note the portal frame is located near the end of the ramp frame.

enter image description here

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  • $\begingroup$ Thanks for input, but I must say I don't understand this possible solution clearly. Can you do any additional sketch? $\endgroup$
    – Grega
    Aug 29 at 17:51
  • $\begingroup$ It is as simple as how a door latch works, instead of working vertically, switch the position to horizontal - use the hydraulic cylinders (attached to the lifting arm in frame) raise the platform, the platform will push the tongues outward to allow the platform to pass, then the tongues recover their position by the springs behind. The only mechanism you need to think about is how to retreat the tongues to the unlocked position to permit the platform to lower down, either manually, or utilize some mechanical control device to unlock automatically. $\endgroup$
    – r13
    Aug 29 at 18:07
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I misread the question at first. Below are the edits. If I understand it well, you just want to stop some rolling pipes. Would the following be enough?

Self locking mechanism

The solution seems to be to have just something else take the weight. Push up the plate and have something else take the weight than the pusher. It's the blue line on the picture. This can be done automatically or manually.

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I was browsing through possible solutions and found these:

Possible locking solutions

A solution in this way could be an option. Or something in the area of over center locking mecahnisms.

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