gas spring sizing

[volaff]

Hello everyone again.
I would have a question for the most experienced.

a seat mounts, by default, an elastic locking gas spring with a f1=100n though, due to the type of locking, tends to let the seat slip.

for a test we mounted on the same seat a gas spring with rigid compression locking with a f1=200n and we noticed two things.

1. with such spring it is practically impossible to move the seat (and there can be being the f4 force in compression about 365 n

2. If the passenger is not sitting on the seat he returns to position very slowly while if the passenger is sitting the seat does not move precisely yet I have a force f1 of 200 n instead of 100 as the original spring.

Where is the hippo according to you?

Thank you very much to anyone who wants to answer.

 

[meccanicamg]

That's right. same international definition of compression springs.

 

[volaff]

That's right. same international definition of compression springs.

I didn't understand your statement...xd!

 

[meccanicamg]

I didn't understand your statement...xd!

was the answer to the post #40

 

[meccanicamg]

Hello everyone again.
I would have a question for the most experienced.

a seat mounts, by default, an elastic locking gas spring with a f1=100n though, due to the type of locking, tends to let the seat slip.

for a test we mounted on the same seat a gas spring with rigid compression locking with a f1=200n and we noticed two things.

1. with such spring it is practically impossible to move the seat (and there can be being the f4 force in compression about 365 n

2. If the passenger is not sitting on the seat he returns to position very slowly while if the passenger is sitting the seat does not move precisely yet I have a force f1 of 200 n instead of 100 as the original spring.

Where is the hippo according to you?

Thank you very much to anyone who wants to answer.

without a pattern where you see the forces cannot assess. Can't you contact the gas spring technician? Call in Ace and help them with their program.

 

[volaff]

without a pattern where you see the forces cannot assess. Can't you contact the gas spring technician? Call in Ace and help them with their program.

I honestly imagined that.
the problem is that we do not have a cad model of the product but only the physical product and are not very practical in the industry.

 

[TECNOMODEL]

a scheme of forces can also be done by hand or with a cad without necessarily having model 3d

 

[volaff]

Good morning, everyone.
I have inserted a sketch but for now without force, just to make it understand the operation.

in practice there is this seat,locked on the ground,which hangs on this set of wheels doing back and forth.

when lowering the lever connected to the gas piston, the compression phase begins, so the user pushing the seat back; and release the lever; vice versa, lowering the lever I go in phase of expansion, and the seat returns back: the gas spring is elastic with f1=100 n.
for a test we mounted on the same seat a gas spring with rigid compression locking with a f1=200n and we noticed two things.

1. with such spring it is practically impossible to move the seat (and there can be being the f4 force in compression about 365 n)

2. if the passenger is not sitting above the seat returns to position very slowly while if the passenger is sitting the seat does not move precisely yet I have a force f1 of 200 n instead of 100 as the original spring.

It is precisely the point 2 that I find very strange, in the sense that, if with a spring of 100 n everything works in expansion, because it should not work with a spring with a greater f1, beyond the problems in the compression phase

Thank you very much and good Sunday to all.

 

[meccanicamg]

There's something wrong with that pattern. The cylinder can't be framed like that... and you don't understand if it's true that the left wheel is hinge and the other is a cart.... but who turns?
However if it does not work is because the cylinder changes direction compared to the fulcres and reverses the bike....otherments would work

 

[volaff]

There's something wrong with that pattern. The cylinder can't be framed like that... and you don't understand if it's true that the left wheel is hinge and the other is a cart.... but who turns?
However if it does not work is because the cylinder changes direction compared to the fulcres and reverses the bike....otherments would work

the scheme is too elementary in fact...the dotted part with zipper and cart is the part that contains "the mechanism" and that is bound on the ground.
in red I put the spring that, clearly, is not framed but free to stretch in both ways (it was right to schematize simpliece).

the problem was to understand why with 200 n (blockable spring) it does not work while with 100 n (elastic spring) it works: that is the seat back.

Could an answer be the different section of fluid passage?? ? in the case of 200 n the pass section is smaller than that of 100 n: this means higher frictions (the fluid passes more slowly) and low extension speeds.

If I can, and please, I insert the tecnicha sheet of the spring with 200 n so maybe there are more info available.

it would be interesting to understand, in addition to f1, f4 and run what are the variables that affect the behavior of the spring and how...

 

[meccanicamg]

It would be more interesting to have the right geometry to analyze. If you have the lightnings that reverse there is no piston that holds...maybe the soft one embarks and just for having 1mm advantageous lever. 200n's shank and doesn't slip and the system remains geometrically rigid... and if it was wrong, it remains wrong.

 

[meccanicamg]

I normally pistons I charge them at different pressure but the mechanics is always the same so nothing changes me braking.

 

[volaff]

I'm sorry I didn't understand much....xd!
Maybe I take a picture to get better

 

[volaff]

hi I have attached two pictures: one piston all compressed and the other piston all extended.

the whole extended stem is: 328.5 mm, while all compressed is 221mm.
♪
f4 = 240 n
K=f1/f2=1.9
fr (friction) = 60 n

the external diameter of the piston is 22 mm and the connection point has diameter 8 mm.

 

[volaff]

was the answer to the post #40

hi apologies if I resume the speech: the progression a1=194 mm(first row, for example, 35% ) represents the value of the spring length when the f1 force is at 35%? ? ?
if f1 = 120 n and progression 35% the total length of spring would be 194 mm when the force f1=0.35*120= 42 n? ? ?

Is that correct?

Thank you very much and sorry for the delay

 

[meccanicamg]

Why don't you call a gas spring representative?
If you arrive after 4 madi to ask you can wait as many to have the answer.
the gas spring does as all springs f=k•x

 

[volaff]

Why don't you call a gas spring representative?
If you arrive after 4 madi to ask you can wait as many to have the answer.
the gas spring does as all springs f=k•x

Thank you!
I with the different total lengths do not find a constant k it is good so

 

[meccanicamg]

will not change much but the k is certainly not constant with a hole and air and oil that must pass us. That's why they give you the diagram.

 

[Mito125]

Good morning, I reconnect because I'm sizing a gas spring for a really simple cover. I attach my calculations to clarify better:Home catalog stabilus page 12 I find that a lift-o-mat would be fine, I would be within the limits imposed, then I go down to page 15 and I find solutions already obliged, so my calculations are not served to anything because there is no commercial application. Then I wonder: how should I do to choose a gas spring? should I repeat the calculations for every element they have available and verify it? the formulas I always took from the site of the stabilus, remembering to put the gas spring to head down (i.e. the cylinder above and the rod below). give me a hint on how to proceed? Thank you.

 

[meccanicamg]

the example "obligated" that is reported in operation way to the catalog is to have the "minimous run" and anyway I would say that to us that we design may also not affect.

other thing, on page 15 you find gas springs in stock or standard. The same thing makes it ace that provides you with a catalog series, but if you want it loaded with the pressure you need, you do it at the factory like you need it. Maybe you wait a few more weeks and you pay something extra but you're sure it's like you wanted it.
Anyway it's always good to talk to a technician and let them check this out and maybe they recommend you another product.