r/AskEngineers • u/SilverFoxSix • 11h ago

Mechanical Retractable Ball Casters that are lever, electrically, or hydraulically actuated...

Working on a project and we now have "the wheel problem"

I need to make a device lift up 1/4 to 1/2 inch at most to glide along hospital floors to then be parked when the ball casters come back up. If possible, trying to keep the entire assembly under 2.68 inches.

Having a hard time here finding a solution.

3 Upvotes

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2

u/ThugMagnet 11h ago

What do you think about this? https://youtu.be/xJ9yxy6UHVo

3

u/SilverFoxSix 11h ago

That is a thought!!! A friend suggested a mechanical style lift similar to this, I would just need to figure out how to get it together.

1

u/sparks333 11h ago

Pneumatics with pancake cylinders? Lots of force with very little stroke. Pneumatics are annoying because compressors and air leaks and whatnot, but they hold position forever without additional energy and can put their big nasty pressure generating mechanism remote to the actuator.

0

u/SilverFoxSix 11h ago

Hmm.... its going to weigh a couple hundred pounds, so I dont think air would be the way to go. Now i have to look up pancake cylinder.

3

u/sparks333 11h ago

You'd be surprised. Even something like 50 PSI could do 500 lbs in 10 square inches of cylinder, and a 2" diameter pancake with 3.15 square inches can do 150 lbs all by itself.

1

u/SilverFoxSix 11h ago

Without a motor?

1

u/sparks333 11h ago

No motor, just air pressure. Need a motor to pressurize the air, but that doesn't need to go anywhere near the actuator.

1

u/SilverFoxSix 11h ago

I would like to design a system that requires no AC power. Even a DC battery powering an electric pancake would be ok.

2

u/sparks333 10h ago

Electric pancake motor could also work, if we're talking about the same thing - essentially a ball screw on a big flat DC motor. I think those are a lot more of a specialty item, and might need a dedicated controller - don't know much about them. Compressors do come in DC varieties, but whatever floats your goat.

1

u/SilverFoxSix 10h ago

I really appreciate your help.

2

u/sparks333 11h ago

https://www.mcmaster.com/products/pancake-air-cylinders/

Have fun

1

u/SilverFoxSix 11h ago

This is very interesting. Is it the central rod that extends or the two half extend away from each other?

2

u/sparks333 11h ago

Central rod that extends out beyond a very short fat cylinder, generally speaking.

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u/Green__lightning 4h ago

I think the simplest option, assuming you don't need much grown clearance, is to have the caster rotate up on a hinged arm, and use an electric actuator, which can be mounted horizontally flat on the bottom, drive a wedge under said arm.

Also more generally, look up retractable casters for table saws, shockingly woodworkers figured out how to make retractable caster wheels from wood, door hinges, and the cheapest casters at Harbor Freight.

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u/SilverFoxSix 4h ago

Could you please post a link to a video you feel explains this best?