Stair Unit Casters

[Andy Haefner]

Hello,
Currently at my high school we have two large stair units for our musicals, they are about 91 inches tall and 104 inches long with a width of 30.5 inches... We want to put casters on them and make them easier to roll around as they are very heavy but we are concerned about the tipping over as they would become very unstable ovce we add casters (usuable space on inside is about 27 in. x 100 in. And the distance we'd have to put large caster in would make it so it has a smaller surface to work with touching the ground... Any recommendations as to how to make it stable without having to increase the width with a platform?

 

[BillConnerFASTC]

Do you intend to leave them on casters when in use? A caster jack or some means for the unit to sit on the floor when in use and be raised on to casters for moving - unoccupied - would solve the problem.

Yes, under 30" and over 90" tall is a problem.

 

[RonHebbard]

Hello,
Currently at my high school we have two large stair units for our musicals, they are about 91 inches tall and 104 inches long with a width of 30.5 inches... We want to put casters on them and make them easier to roll around as they are very heavy but we are concerned about the tipping over as they would become very unstable ovce we add casters (usuable space on inside is about 27 in. x 100 in. And the distance we'd have to put large caster in would make it so it has a smaller surface to work with touching the ground... Any recommendations as to how to make it stable without having to increase the width with a platform?

Do you intend to leave them on casters when in use? A caster jack or some means for the unit to sit on the floor when in use and be raised on to casters for moving - unoccupied - would solve the problem.

Yes, under 30" and over 90" tall is a problem.

@Andy Haefner Have you considered adding inverted carpet to the bottom and sliding them rather than rolling them?
OR using inner tubes and air to lift them clear of the deck and onto casters while moving them then deflating and dropping them back down to solidly resting upon the deck once in position? For home-brew pneumatic casters, think of it this way: Build two sturdy, glued and screwed, plywood boxes. For talk's sake let's say the boxes are each approximately 30" square by about 6 to 8" deep. One box sits on the deck with its open side up. The other slightly larger box sits on top inverted. The first box has casters on the bottom, triple-swivels possibly. The bottom box contains an automotive inner tube. When you inflate the inner tube it expands and raises the upper box enough to clear the floor thus your stair units are now free to roll on your home-brew giant air-bag casters. When you deflate the inner tube gravity compresses the air out and the inverted upper box descends until it again is solidly in contact with your deck. Simple when you type it fast. You need to construct the boxes very solidly with lots of good glue and screws as the same pneumatic pressure being employed to lift and support is also trying to push the walls of your boxes apart.
Toodleoo!
Ron Hebbard

 

[Andy Haefner]

@RonHebbard @BillConnerFASTC
We would do something like that but our issue is that we are doing legally blonde and want to have Elle ride out on the stairs in a scene... Any other suggestions? Would lots of small casters create more stability than 4 large ones?

 

[BillConnerFASTC]

It's the base to height ratio I look at first. You might design the casters so they only lift the "frame" a tiny bit, so if it tips it is quickly grounded. 3:1 height to span of support points is my starting point.

No way you can disguise outboard casters - ones mounted to the outside of the frame?

Add 500 or so pounds of counterweight as low as possible (steel, tube sand, or concrete) but more and/or better casters?

 

[Butch!]

@RonHebbard @BillConnerFASTC
We would do something like that but our issue is that we are doing legally blonde and want to have Elle ride out on the stairs in a scene... Any other suggestions? Would lots of small casters create more stability than 4 large ones?

OSHA doesn't allow someone to be on a rolling scaffolding (which is what the stair technically is) while it is being moved unless the width of the base is more than 1/2 of the platform height. That means the base must be 45 1/2". Have you thought about building a 4' by 9' rolling platform and securely bolting the stair unit to it? That would comply with OSHA and give you a heavier base to help prevent a tip over.

 

[macsound]

To tack onto the larger platform idea, it could probably be very well concealed and low to the ground, but I assume there was a reason the staircase was designed to be this size in the first place.