Struggling to design a mechanism for a tri-folding gate

[fanofakirakurosawa]

Hello, a friend of mine asked me to create a mechanism for a tri-folding gate. The thing is: it has a peculiar sequence when it's opened and I'm really stuck thinking this mechanism. Is there a good book/source about mechanics where I can find inspiration? Thanks in advance

 

[Baluncore]

Welcome to PF.

If there is a good book, then I would also be interested. I have built a few special gates, but have never found a book on the subject. Reading, thinking and experimenting, is the way I have progressed.

Maybe if you describe the situation, and provide a sketch, we will be able to source some references to applicable mechanisms.

 

[jrmichler]

Is there a good book/source about mechanics where I can find inspiration?

Yes. The title is 507 Mechanical Movements, and it was first published in 1869 according to the title page of my copy. There are several different editions for sale on Amazon. It may not have the exact linkage you need, but you certainly will find some ideas. This is an excellent book for somebody interested in mechanical gadgets. If you are not careful, it will suck you in to the very end.

 

[fanofakirakurosawa]

Yes. The title is 507 Mechanical Movements, and it was first published in 1869 according to the title page of my copy. There are several different editions for sale on Amazon. It may not have the exact linkage you need, but you certainly will find some ideas. This is an excellent book for somebody interested in mechanical gadgets. If you are not careful, it will suck you in to the very end.

Sadly I can't get that book since I'm not from US and I can't buy some items from Amazon. Anyway I borrowed a book from my local University's library, it's called Design of Machinery by Robert L. Norton. I'll start from there. Thank you anyway.

 

[fanofakirakurosawa]

Welcome to PF.

If there is a good book, then I would also be interested. I have built a few special gates, but have never found a book on the subject. Reading, thinking and experimenting, is the way I have progressed.

Maybe if you describe the situation, and provide a sketch, we will be able to source some references to applicable mechanisms.

Sorry, I forgot to attach some sketch. Here's a video of how the gate should move. Just a quick representation of the sequence.

 

[jedishrfu]

Google Books may have a preview:

https://www.google.com/books/edition/507_Mechanical_Movements/JweakTAk798C?hl=en

also the internet archive:

https://archive.org/details/Mechanical_Movements_507/page/n5/mode/2up

 

[jedishrfu]

Regarding your fan-fold door, this is a common scheme for closets in the US. The door will have pins at the top and bottom following a straight track to ensure it opens correctly.

In your case, it seems that there is an additional constraint: the door can't pass a certain horizontal boundary. Is that correct?

What is the purpose of your gate?

 

[Baluncore]

Sorry, I forgot to attach some sketch. Here's a video of how the gate should move. Just a quick representation of the sequence.

If it is a gate for people or animals, it will be very dangerous.

The third leaf operates like a cutter, against the right-hand post, (not shown).

The leafs one and two reach a maximum velocity, with maximum force being applied along leaf three, as the gate finally closes.

A person trapped at the end of leaf three, will be unable to reach the hinge between leafs one and two, to relieve the pressure or escape being crushed.

 

[fanofakirakurosawa]

Regarding your fan-fold door, this is a common scheme for closets in the US. The door will have pins at the top and bottom following a straight track to ensure it opens correctly.

In your case, it seems that there is an additional constraint: the door can't pass a certain horizontal boundary. Is that correct?

What is the purpose of your gate?

It's for a very specific furnace. The sequence it's peculiar due the limited space.

 

[fanofakirakurosawa]

If it is a gate for people or animals, it will be very dangerous.

The third leaf operates like a cutter, against the right-hand post, (not shown).

The leafs one and two reach a maximum velocity, with maximum force being applied along leaf three, as the gate finally closes.

A person trapped at the end of leaf three, will be unable to reach the hinge between leafs one and two, to relieve the pressure or escape being crushed.

It's not for living beings. Specific application. And it can't operate if there are persons close to the gate. Also it will operate at a low velocity.

 

[Baluncore]

There are three distinct phases of operation, so a simple linkage will not meet the requirement. There will need to be a sequence controller, with a parameter t, that sequences the operations.

What sources of power are available to move the gates?
How wide are the gates, in metres?
What do the gates weigh, in kg?
What are the minimum and maximum times, to open or close, seconds or minutes?

 

[fanofakirakurosawa]

There are three distinct phases of operation, so a simple linkage will not meet the requirement. There will need to be a sequence controller, with a parameter t, that sequences the operations.

What sources of power are available to move the gates?
How wide are the gates, in metres?
What do the gates weigh, in kg?
What are the minimum and maximum times, to open or close, seconds or minutes?

Source power: electric motor.
Gates are 1 m (3,3 ft) wide.
Every fold weighs around 150 kg (331 lb).
The time isn't defined yet.

 

[Lnewqban]

Hello, a friend of mine asked me to create a mechanism for a tri-folding gate. The thing is: it has a peculiar sequence when it's opened and I'm really stuck thinking this mechanism. Is there a good book/source about mechanics where I can find inspiration? Thanks in advance

Could the floor and the ceiling be used?
If so, are those two planes strong, flat and parallel?

 

[fanofakirakurosawa]

Could the floor and the ceiling be used?
If so, are those two planes strong, flat and parallel?

Only the floor, the ceiling is too high. But it's possible to build some high structure. The door is 5 meters tall

 

[jrmichler]

I am unable to view the video in Post #5. I click on it, and it goes black in both Chrome and Edge.

 

[fanofakirakurosawa]

I am unable to view the video in Post #5. I click on it, and it goes black in both Chrome and Edge.

It's a video uploaded to Google Drive. Here's the link:
drive.google.com/file/d/1DfO0TQuo-9SZpwmLib1KK8SX3pZyK8kg/view?usp=drivesdk

 

[DaveC426913]

Sorry, I forgot to attach some sketch. Here's a video of how the gate should move. Just a quick representation of the sequence.

I can't seem to get this to play. And when I skip ahead, the whole video is just black end-to-end.

Ah. I had to open it in its own window to see it play.

 

[DaveC426913]

The thing is: it has a peculiar sequence when it's opened

Do you mean it has to open/close in that sequence? It's not just a simple two-hinge tri-fold mechanism?

 

[fanofakirakurosawa]

Do you mean it has to open/close in that sequence? It's not just a simple two-hinge tri-fold mechanism?

Yeah, that is the sequence due a limited space. Sadly there are no other options.

 

[Tom.G]

That greater-than-90° motion for pivot #1 makes this somewhat involved. If you can get the pivots points on a straight line, it is trivial.

I realize the gray lines show the travel paths, however I am assuming that the two horizontal lines would comprise a physical track for the traveling gate joints, and also enclose a chain and a cable (or 2 chains).

Anyhow, here goes.

Referencing your video,

Starting at top left, label the fixed pivot #1,
the middle pivot #2
then #3

Motive power at the right end of the track.
Two roller chains needed for unfolding (or cable + roller chain):

Rotate links #1 & #2:
A cable/chain inside the track, with an idler pulley in the track where pivot #3 enters the straight track. End of rope/chain attached to gate near pivot #3 and to motive power at right end. Pull until pivot #3 enters track

Rotate all links, straightening gate:
Continuous Roller Chain inside track with idler to left of where point #3 enters track.
Pivot #3 has a sprocket that engages roller chain. Sprocket turns drive axle that straightens pivot #3 (unfolds last segment of gate).
When last gate segment hits rotation stop, the entire gate starts extending to Closed position.

Refolding is left as an exercise for the reader.

Interesting problem.

Have Fun,
Tom

 

[fanofakirakurosawa]

That greater-than-90° motion for pivot #1 makes this somewhat involved. If you can get the pivots points on a straight line, it is trivial.

I realize the gray lines show the travel paths, however I am assuming that the two horizontal lines would comprise a physical track for the traveling gate joints, and also enclose a chain and a cable (or 2 chains).

Anyhow, here goes.

Referencing your video,


View attachment 357798

Starting at top left, label the fixed pivot #1,
the middle pivot #2
then #3

Motive power at the right end of the track.
Two roller chains needed for unfolding (or cable + roller chain):

Rotate links #1 & #2:
A cable/chain inside the track, with an idler pulley in the track where pivot #3 enters the straight track. End of rope/chain attached to gate near pivot #3 and to motive power at right end. Pull until pivot #3 enters track

Rotate all links, straightening gate:
Continuous Roller Chain inside track with idler to left of where point #3 enters track.
Pivot #3 has a sprocket that engages roller chain. Sprocket turns drive axle that straightens pivot #3 (unfolds last segment of gate).
When last gate segment hits rotation stop, the entire gate starts extending to Closed position.

Refolding is left as an exercise for the reader.

Interesting problem.

Have Fun,
Tom

Thank you so much Tom I really appreciate your time. But there is one problem, when I explained this to my friend he told me that the starting point is at 180° not at that >90° angle. It seems there was a change of plans. They decided to change the starting point because the gate would block the view of a person (Fig 1). The new sequence starts like in Fig 2. Sorry for asking for help in this new sequence but I'm lacking of time and creativity in this mechanism, I'm doing this in my little free time

 

[Tom.G]

Unless there are other constraints, that makes the solution trivial.

If other constraints exist, please supply a drawing.

Use 3 (or more) sliding sections that, when retracted, are in front of each other. Slide them to the right when needed. Similiar to a large panel truck whose side cargo door slides to open; another example is a "pocket door", more often seen in older houses where a door slides inside a wall to open.

Again, use a continuous chain or cable to close/open the gate.

Cheers,
Tom

p.s. Out of curiousity, what is the usage/environment of this project?