Hangar Door Stuck Open

topgun260

topgun260

Pre-takeoff checklist
Joined
Dec 21, 2013
Messages
332
Display Name
Topgun260
I opened my Schweiss hydraulic hangar door all the way open today and now it won't close. The motor runs but the door seems stuck. For whatever reason I opened it further than I usually do today. Any suggestions?
I've tried climbing up a ladder and hanging off the end of the door to try and break it loose, but it didn't work. It seems only one ram is stuck.
1000010350.jpg
 
Last edited:
I think that would cause the side that isn't jammed to come down. One side will move a small amount. The other doesn't move at all.
 
MauleSkinner said:
I’d call Schweiss. The “hanging off the end of the door” part already has me nervous.
Click to expand...

I'd like to x2 this one. If it seemed it opened past where you think it usually does it may have over traveled or over-pressured. If there is a problem with the piston and/or seals internal it could be hydro-locked and have the kind of pressures inside you really don't want to play with in that scenario. This is what we call good 'ol fashioned bad ju ju waiting to happen. You really need a way to support the door in position, then remove the cylinders and have them looked at properly. Hydraulic cylinders aren't particularly difficult to work on with the right tools, but they can be incredibly dangerous to work on when things go pear shaped ...
 
Salty said:
A human body would be maybe 5% of the weight of the door.
Click to expand...
Yes and no ... you could do the math and say what the force is of a given weight at that distance (12 to 16 ft on a door like that) but it doesn't matter. The door is currently in fairly mode so why do something incredibly unsafe like that. I promise that if it gives way suddenly and you fall from that distance your not going to like how that one ends. Now, having taken a quick look at how the Schweiss system works I would really really REALLY advise calling a professional if you don't know how to work on it. Schweiss uses a back flow preventer they call a velocity fuse. Playing with hydraulics in failure mode and not knowing what will happen without the suitable safety precautions is a recipe for disaster. This could be the velocity fuse, it could be a line collapsed, it could be piston seals failed and the piston has lodged itself into the barrel. I have a really good working knowledge and lots of experience with hydraulic systems and I would be calling the professionals on this one ...
 
Hydro lock. Have done it with the crane on my service truck swinging a 6,000 lb load. Wasnt paying attention and exceeded the 70 degree limit. Cracked the line just a bit to see oil start leaking. Boom didnt move. But was now able to drop the boom below 70 degrees. More oil leaked. Tighten line. Carry on.

If you're afraid of cracking lines at the cylinder, follow the lines elsewhere.

It does matter which line you try cracking. I believe the lower is the one that needs to crack
 
Last edited:
MauleSkinner said:
I’d call Schweiss. The “hanging off the end of the door” part already has me nervous.
Click to expand...
Yeah. Clearly not going to work. You have to stand on top of the door and jump up and down. Everyone knows that!

looney-tunes-coyote.gif
 
Last edited:
Salty said:
A human body would be maybe 5% of the weight of the door.
Click to expand...
The CG of the door is roughly at its center. Adding 5% hanging off the far end of the cantilever arm would alter the system considerably. I'm not convinced that's a viable resolution technique at any rate (obviously it was not). Nothing to sneeze at, is all I'd say.

In any case, a typical 40' hangar door weighs 4,000 lb? What is the failsafe if the hydraulics were to give out with the door up? Maybe that failsafe has prematurely engaged and is preventing the door from lowering?
 
DJTorrente said:
The CG of the door is roughly at its center. Adding 5% hanging off the far end of the cantilever arm would alter the system considerably. I'm not convinced that's a viable resolution technique at any rate (obviously it was not). Nothing to sneeze at, is all I'd say.

In any case, a typical 40' hangar door weighs 4,000 lb? What is the failsafe if the hydraulics were to give out with the door up? Maybe that failsafe has prematurely engaged and is preventing the door from lowering?
Click to expand...
I agree that it's not likely to help any, in any case.
 
Racerx said:
Hydro lock. Have done it with the crane on my service truck swinging a 6,000 lb load. Wasnt paying attention and exceeded the 70 degree limit. Cracked the line just a bit to see oil start leaking. Boom didnt move. But was now able to drop the boom below 70 degrees. More oil leaked. Tighten line. Carry on.

If you're afraid of cracking lines at the cylinder, follow the lines elsewhere.

It does matter which line you try cracking. I believe the lower is the one that needs to crack
Click to expand...
So last night, in the middle of the night, the wind picked up considerably. I went to check on the hangar, tried the door, and it worked just fine. I think maybe I did exceed the limit and/or it jammed, and the wind had enough force to unjam the door. In any case, I had a friend who worked on hydraulics a good share of his life come look at it this morning. He said everything looks fine and also showed me a release that I can push if the door is open and the power goes out that I can push and let the door come down.
This failure mode wasn't one where the door was going to suddenly drop and swing closed.
Thanks for all the concern.
 
topgun260 said:
So last night, in the middle of the night, the wind picked up considerably. I went to check on the hangar, tried the door, and it worked just fine. I think maybe I did exceed the limit and/or it jammed, and the wind had enough force to unjam the door. In any case, I had a friend who worked on hydraulics a good share of his life come look at it this morning. He said everything looks fine and also showed me a release that I can push if the door is open and the power goes out that I can push and let the door come down.
This failure mode wasn't one where the door was going to suddenly drop and swing closed.
Thanks for all the concern.
Click to expand...
Good to hear, and the best news is you learned some things about your door.:rockon:
 
topgun260 said:
So last night, in the middle of the night, the wind picked up considerably. I went to check on the hangar, tried the door, and it worked just fine. I think maybe I did exceed the limit and/or it jammed, and the wind had enough force to unjam the door. In any case, I had a friend who worked on hydraulics a good share of his life come look at it this morning. He said everything looks fine and also showed me a release that I can push if the door is open and the power goes out that I can push and let the door come down.
This failure mode wasn't one where the door was going to suddenly drop and swing closed.
Thanks for all the concern.
Click to expand...
Just like a computer, turn it off, wait few minutes, turn it back on :)
 
Charlie Golf said:
Proving that if you ignore a problem long enough, it'll go away. (Man Code Rule 1.1)
Click to expand...
One of my first real jobs in engineering was intern to the Ops Mgr. at a power gen station. He was pursuing a Masters in operational planning at the time, so a lot of my work involved assisting him writing his thesis. Nothing sinister, kind of as a research assistant works for a professor writing a research paper. The job was funding his masters, so it was arguably work-related.

One thing I learned from that experience is that any valid planning decision needs a base case: what is the most likely outcome if you choose to do nothing.
 
Charlie Golf said:
Proving that if you ignore a problem long enough, it'll go away. (Man Code Rule 1.1)
Click to expand...

is that similar to the Woman Code of Automotive Idiot Light?

(yes, it's an old stereotype and it's a joke)
 
DJTorrente said:
One of my first real jobs in engineering was intern to the Ops Mgr. at a power gen station. He was pursuing a Masters in operational planning at the time, so a lot of my work involved assisting him writing his thesis. Nothing sinister, kind of as a research assistant works for a professor writing a research paper. The job was funding his masters, so it was arguably work-related.

One thing I learned from that experience is that any valid planning decision needs a base case: what is the most likely outcome if you choose to do nothing.
Click to expand...
Someone - I wish I could remember who it was - taught me to slow down and not act too quickly if it wasn’t a true emergency. The way he put it was “don’t just do something - stand there!”
 
DJTorrente said:
One thing I learned from that experience is that any valid planning decision needs a base case: what is the most likely outcome if you choose to do nothing.
Click to expand...

Around here, "decision needs a base case" indicates the amount of beer necessary prior to any result will occur with all the nearby hangar pilots dropping in;)
 
Charlie Golf said:
Proving that if you ignore a problem long enough, it'll go away. (Man Code Rule 1.1)
Click to expand...
Most likely the time and wind caused the ram to "settle" just enough where it wasn't full pressure locked out
 
You must log in or register to reply here.
Back
Top