Harbor Freight lift table conversion to air
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Cruiser
Joined: Feb 2011
Posts: 205
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From: Goode, Va
Harbor Freight lift table conversion to air
I have herd that some people have converted the Harbor Freight foot powered motocycle Hydraulic lift table to air power,anybody ever done this? if so could give some good instruction on how to do this and where you got the parts.
Last edited by kdodd; Jan 31, 2012 at 12:35 AM.
Road Warrior
Joined: Nov 2008
Posts: 1,296
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From: Cheltenham, UK
I don't know the specifics of this piece of equipment, but I do specialise in hydraulics
I would say, based on my experience with jacking equipment, that this would be somewhere between impossible and extremely difficult.
In jacking systems you typically expect pressures of around 300 bar in a hydraulic jack (4500 psi). The maximum pressure you can run an air system at is 7 bar (105 psi)
This would mean you would need a much bigger cylinder to give you the equivelant lifting force. Could do the calc for you if you want but I would need the dimensions o the hydraulic cylinder fitted.
I would say, based on my experience with jacking equipment, that this would be somewhere between impossible and extremely difficult.
In jacking systems you typically expect pressures of around 300 bar in a hydraulic jack (4500 psi). The maximum pressure you can run an air system at is 7 bar (105 psi)
This would mean you would need a much bigger cylinder to give you the equivelant lifting force. Could do the calc for you if you want but I would need the dimensions o the hydraulic cylinder fitted.
Road Warrior
Joined: Nov 2008
Posts: 1,296
Likes: 3
From: Cheltenham, UK
Just by way of illustration, a 2" hydraulic cylinder would require a 12" pneumatic cylinder if you wanted to do a straight swap.
you can do as boogaloodude suggests, or investigate air / oil intensifiers
you can do as boogaloodude suggests, or investigate air / oil intensifiers
Road Master
Joined: Mar 2010
Posts: 934
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From: SE Wisconsin
Just off the top of my head heres the way I would figure it using rough numbers.
The load you want to lift is 1000 lbs. Your shop air pressure is 100psi, if you were lifting a strait up load you would need a piston at least 10 square inches.
(Example: A 4 inch piston has 12.5 square inches area, times 100psi your lift potential is 1250 lbs.)
But the table has a mechanical advantage, roughly 4 to 1. Meaning for every inch the jack moves the table rises about 4 inches. So you need to increase your piston area by 4 times. You need to lift 4000 lbs at the jack for a 1000 lb load at the table.
{Example: A 7.5 inch piston has 44 square inches of area so it would lift 4400 lbs with 100psi}
Or, a pair of 20 square inch pistons would work as well. You get the point.
After settling on the cylinders needed, the air over oil is the way to go. The reason, air is compressible, an air controlled movement would be a little more erratic and spongy, but much faster. Oil is not compressible and easy to control, but much slower. With air over oil, you get the best of both worlds, air charged and oil controlled.
The load you want to lift is 1000 lbs. Your shop air pressure is 100psi, if you were lifting a strait up load you would need a piston at least 10 square inches.
(Example: A 4 inch piston has 12.5 square inches area, times 100psi your lift potential is 1250 lbs.)
But the table has a mechanical advantage, roughly 4 to 1. Meaning for every inch the jack moves the table rises about 4 inches. So you need to increase your piston area by 4 times. You need to lift 4000 lbs at the jack for a 1000 lb load at the table.
{Example: A 7.5 inch piston has 44 square inches of area so it would lift 4400 lbs with 100psi}
Or, a pair of 20 square inch pistons would work as well. You get the point.
After settling on the cylinders needed, the air over oil is the way to go. The reason, air is compressible, an air controlled movement would be a little more erratic and spongy, but much faster. Oil is not compressible and easy to control, but much slower. With air over oil, you get the best of both worlds, air charged and oil controlled.
Road Warrior
Joined: Nov 2008
Posts: 1,296
Likes: 3
From: Cheltenham, UK
The air over oil solution is simply changing the motive energy for driving the hydraulic pump, nothing more, nothing less.
With jacking solutions you typically use human power (hand pump) or an electric driven pump set. This gives you a third option.
I guess the key question is why you want to do this? Is it because you have a compressor already and want to save the effort / hassle of pumping by hand?
With jacking solutions you typically use human power (hand pump) or an electric driven pump set. This gives you a third option.
I guess the key question is why you want to do this? Is it because you have a compressor already and want to save the effort / hassle of pumping by hand?
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I bought the air over hydraulic pump from Harbor Freight.
Had it for 2 years already.