Globe Automobile Hoist

U.S. Patent No. 1,720,980

 
Below are some pictures of a Globe in-ground automobile hoist.  It was probably installed in the early 1930's and is located on the grounds of the Mt. Wilson Observatory in the mountains above Pasadena, California.  It has suffered from lack of use and neglect for the past several years and my brother Ken and I were asked if we could help bring it back to usable and safe condition.  Having no knowledge of the working principles or experience with such devices we of course agreed to take the project on.  Fortunately, there was a patent number on the tag and looking at the patent provided much needed insight into what we needed to do.  We found the system works by air pressure pushing a column of oil on the bottom of the piston to raise the hoist.  We suspected the oil level was low but decided to replace all the oil rather than just adding some.

We discovered that there was a valve at the bottom of the inside of the piston that when opened allowed the oil to flood the piston when lift air pressure was applied.  To remove the old oil Ken made a special cover plate with a hole for pressurized air and also a hole for a long copper dip tube that reached the bottom.  We flooded the piston with the old oil, closed the valve and then used an outside air pressure source to push the oil up the dip tube and into the waste barrel.

The main problem did turn out to be a low oil level.  Now that it is back in working condition it will make it much easier for the Observatory staff to do routine maintenance on the vehicles in this relatively remote location.  The next part of the project is to try to find some slide-on accessory swing out arms so modern vehicles can be lifted safely.  If you have knowledge of a source for such things please let me know at:


 
The hoist partially raised.

 
The cover plate protecting the inside of the piston.
There are several holes through the piston at different heights for a safety pin.
 
Temporary cover plate with holes for air pressure (blue hose) and the long copper dip tube for oil removal.
Note the color of the old oil.

 
A home made fitting for lifting an old truck no longer there.
Fittings we are looking for would need to fit on this 5" wide x 3/8" thick plate.
 
 
 
The pipe on the right admits air pressure to the top of oil tank pushing it up the central tube to the bottom of the piston.  Relieving the air pressure lowers the piston.  You can click on the picture or here for a better view of the patent drawing.

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Updated: 02/06/06

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