pneumatic cylinder stroke question

[Mordakai]

I am gonna open my barn door with a pneumatic cylinder. How do I calculate the stroke needed to swing a 7 foot wide door 90°?

Thanks mordakai

 

[kspwski]

It really depends on the mounting and any linkage. Is the door swinging horizontal or vertical? Do you know where/how you want to mount the cylinder? Picture would help. Cool idea!

 

[theoldwizard1]

Learn trigonometry.

 

[larry_g]

I am gonna open my barn door with a pneumatic cylinder. How do I calculate the stroke needed to swing a 7 foot wide door 90°?

Thanks mordakai

There are probably 10 different linkages that you could EASILY use and each would take a different cylinder. Keep in mind that the shorter cylinder stroke mechanisms will take a larger bore cylinder. Also in designing your mechanism do you want one that basically self locks or one that you can easily pull on the door and override the opener.

I would suggest that you pencil out a few different designs. Don't forget that how fast the door moves is controlled with flow controls and not a pressure regulator.

lg
no neatsig line

 

[Mordakai]

I'm thinking that I would mount the cylinder on the door at the bottem swinging horizontal with some pivot brackets on both ends of the cylinder. I would like to keep it simple as possible.

 

[astroracer]

I designed something similar to open armored doors on Humvee's a few years ago. An armored door weighed 1000lbs and 95th pecentile soldiers could not open them...
Look at the Destaco style over-center clamps. That is what I based my design on and a 3" stroke cylinder would swing the doors past 72 degrees. Worked great. All you have to do is work with the pivot points to keep it from going over-center and still have enough leverage to actually articulate the hinge geometry.
You say you want to "keep it simple". THAT would be opening the door by hand...
Mark

 

[larry_g]

I'm thinking that I would mount the cylinder on the door at the bottem swinging horizontal with some pivot brackets on both ends of the cylinder. I would like to keep it simple as possible.

In that scenario then you have an equilateral triangle. From the pivot point of the door you measure out from the hinge point to the attachment point on the door. Then the stroke of the cylinder is going the be the square root of 2x that distance. You also have that cylinder imposing on the opening of the door width and when closed the cylinder is protruding into the room taking up space and being vulnerable to damage. Not how I would do it.

lg
no neat sig line

 

[Mordakai]

Thank you. Got it.

 

[gungatim]

Learn trigonometry.

yep. everytime someone says they will never will use math they learned in school, I always laugh and explain you'll use it more than you think you would if you just think about it. want to calculate the bolt pattern of a 5 lug ford? divide the circle into triangles. build rafters for a shed? estimate how much drywall or plywood for a project? how many shingles do you need for a 5:12 pitch garage roof? calculate gear ratio for a sprocket? speedo correction for larger diameter tires? or maybe just scale up a cookie recipe to the most efficient use of ingredients...

if they would have just made story problems more relatable to the real world, maybe we would teach math properly in schools these days...

 

[nadogail]

As I recall, those story problems of my youth were relevant to the real world. My personal world of my youth was partly based on my own fantasies.

It's true that there is no longer a need for American students to have a grasp of the English currency system; their pounds, shillings and pence. But the old problems about ratio and proportion, relative speed of trains, budgeting and simple geometry are still all relevant.

I am staggered by the apparent lack of understanding, by many, of 3,4,5 triangles, powers of 10 and other IMHO simple concepts.