[SML] Pneumatic Wagon Brakes

[gbierly at dejazzd.com]

> On Jan 30, 2019, at 4:22 PM, Jon Lagerquist via Stagecraft <stagecraft at theatrical.net> wrote:
> 
> Here is a drawing of the latest version we have used with good reviews.
> The key to this is that you regulate the pressure to the foot so it does
> not lift the unit but provides enough resistance to keep the unit in
> place. The box serves to absorb the horizontal load so the cylinder does
> not get tweaked.
> 
> The next time I build these I will likely use spring return cylinders to
> reduce the air requirements.
> 
> Jon

I really like that design.  We have both double acting as shown and single acting (spring return) and find the single acting much easier to deal with.  Instead of your cool box we have welded a steel plate to the threaded bolt right out of the cylinder and haven’t had any issues with horizontal load tweaking anything.  (knock on wood)

We have the steel plates drilled with matching hole pattern that we can bolt a triple swivel caster to the plate.  When we apply air it pushes the casters down lifting the platform.  Again it puts all the horizontal stress onto the cylinder but again have been lucky to not have an issue.  It also requires much more clearance but if we loose air pressure it fails into the stationary mode for safety.

University of MD had these that are a steel plate on guides 


The last design I reverse engineered from Spoon Group that pushes a plunger in the caster to stop rolling and swiveling.  The cartmaster caster is available from Rose Brand.   It won’t carry as heavy loads but I can typically use 4 with a larger set of triples to brake larger pieces.  



Greg Bierly
Performing Arts Center Manager
Hempfield High School





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