SXDFC
Topic Author
Posts: 1691
Joined: Sun Dec 09, 2007 6:07 pm

Hydraulic Lifts For Planes, How Do They Work?

Wed Dec 17, 2008 5:30 pm

In many MX pictures on this site, and else where I have seen planes on hydraulic lifts under the wing and on the side of the plane. I would like to know how these devices work, especially the ones that are placed on the side of the plane. Is it a powered magnet that attaches to the skin of the plane?
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
Tristarsteve
Posts: 3373
Joined: Tue Nov 22, 2005 11:04 pm

RE: Hydraulic Lifts For Planes, How Do They Work?

Wed Dec 17, 2008 5:58 pm

I think you are talking about jacks, where the aircraft is jacked off the wheels for maint.
The jacks fit into special jacking pads. These are usually fitted by removing a panel and bolting the pad onto the aircraft. Sometimes there is no panel to remove at the nose. The six bolt holes are filled with plastic inserts that are removed. The jacking pads are kept with the jacks and are special for each aircraft type.
 
Dalmd88
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Joined: Fri Jul 28, 2000 3:19 am

RE: Hydraulic Lifts For Planes, How Do They Work?

Wed Dec 17, 2008 6:05 pm

For the nose jacks on planes like a 757/767 the jack mount fixture is screwed into mount holes on the side of the plane. When not is use the holes are plugged with flush screws. The jack mounts for the wing jacks screw into similar holes under the wing. Some aircraft, like the MD80 use this type for the nose and tail also. Magnets wouldn't work too good. Aluminum structure isn't very attracted to magnets.

The jacks themselves are actuated by shop compressed air. You simply step on the lever and they slowly pump up. Just like a pump type bottle jack you might use on a car. Care must be taken when jacking that the plane goes up level. There are bubble gages mounted in the wheel wells to show the condition.
 
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HAWK21M
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Joined: Fri Jan 05, 2001 10:05 pm

RE: Hydraulic Lifts For Planes, How Do They Work?

Wed Dec 17, 2008 8:45 pm


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Photo © Wenzai

Sounds like you are reffering to aircraft hydraulic jacks.
These are hydraulically operated,screw jack ring locked at small intervals of lift to cater to a loss of fluid.
Placed at four points around the aircraft "normally".
There is a level plumb bob/spirit level in MWW normally used to monitor the jacking process to ensure equal mvmt.
regds
MEL

[Edited 2008-12-17 12:49:53]
I may not win often, but I damn well never lose!!! ;)
 
KELPkid
Posts: 5247
Joined: Wed Nov 02, 2005 5:33 am

RE: Hydraulic Lifts For Planes, How Do They Work?

Wed Dec 17, 2008 9:44 pm



Quoting SXDFC (Thread starter):
Is it a powered magnet that attaches to the skin of the plane?

That wouldn't work on an airplane. Aluminum (and its alloys, as used in aviation) aren't magnetic materials  Wink
Celebrating the birth of KELPkidJR on August 5, 2009 :-)

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