# Self Locking, Movable Stair Unit



## rcgtheater (May 7, 2009)

I need to build a stair unit that will be 4' Tall, 4' Wide, and 8' Long. Thats the easy part. It needs to move, and it needs to be enclosed on all sides. I need to make sure that it won't move when my actors are on it. I am thinking of some kind of weight sensitive mechanism that will allow it to raise up when nobody is on it, but will 'lock' down on the stage floor when someone is sitting/standing on it. Has anyone ever built anything like this?


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## derekleffew (May 7, 2009)

You've been observing the stockers in your big-box store, haven't you?

 ​ 
 _Spring-Loaded Casters (1–5 step models) Retract under weight to grip the floor. Step off and the ladder is ready to roll.
_​ ​ _JStep-Down Lock
(6–16 step models)
Your weight on the bottom step actuates the lock and lowers the feet to floor. Step on release pedal to roll.
_​From Industrial Steel Rolling Safety Ladder w/ Handrails - Ballymore - Mfg# H318P. 

Not a bad idea, but I suspect you'll need to do a fair amount of trial and error with different spring tensions.

See also the threads http://www.controlbooth.com/forums/scenery/2209-moving-scenery-wagons.html and http://www.controlbooth.com/forums/scenery/10335-braking-marley.html.


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## Van (May 7, 2009)

Never actually built anything exactly like that, but I think Derek is on the right track! check those other threads and then get back to us with more questions.


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## cprted (May 7, 2009)

A show I worked on recently used air rams to great success on a large (16x18x18 ish) rolling stair monstrosity. Small air tank inside the unit, flip the switch and the rams lift the unit 1/4" off the ground. When the rams are engaged, it is going nowhere. This system is also good because if the system fails, you don't have a large immovable object in the middle of the stage.


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## jneveaux (May 7, 2009)

the air brake idea sounds interesting. do you have a schematic and some specs for the components you used? all loads and engineering would need to be application specific of course. just wondering exactly wht you did. thanks.


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## cprted (May 8, 2009)

I didn't actually design or build the system. I'll email the TD from that one and see if I can get the specs. But basically it works as follows:



Edit: My quasi-schematic isn't working


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## dkjohnny (May 9, 2009)

The system I have worked with or on used "Pancake" cylinders form McMaster Carr. Typically the cylinder has a 1" throw, mounter to the wagon, and the theaded ram can have a stem type caster that lifts the load onto wheels, or a rubberized stem that serves as a brake for the unit. 1/8" - 1/4" tubing/air tank and lever valve finishs the system.


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## draco17315 (May 9, 2009)

If you want to go the lo tech way....what we have done in the past is 

1) build your stairs
2) skin them all the way around but leave the back open
3) put your steps on casters
4) add a back "panel" or door that opens and closes to give that finished look to your stairs from all sides but still giving access to the inside of the stairs
5) place some metal handles inside the stairs, on the frame work, for gripping
6) place a 2X4 across the center (where the "floor" would be)or you can use two and put one towards the front and one towards the back of the stairs (again where the "floor" would be) giving a crew member a foot rest and or a foot and toosh rest
7) load the stairs with your favorite (or least favorite) crew member, they use the two by four on the bottom of the stairs to place their feet and toosh on like a chair
8) close the back panel and push prop into place
9) the crew member inside puts feet on the floor (like the Flinstones used their feet to as breaks in their cars) and use the handles to get a good grip on the frame work of the stairs

basic, but really works well....especially when on a budget or can't find the right materials and you are on a time crunch....good luck 

Joe


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