Electric brakes/floor locks

[Crisp image]

Good morning Brains Trust,
I build sets for the local youth theatre Co and I am wondering if there is a solution to my problem.
When we have trucks (or wagons) that move on and off stage and need to lock them in place we have been using floor locks that are attached to the outside of the trucks which create tripping hazards and also don't allow for neat storage off stage.
What I am after is low voltage (12V) electric operated floor lock system that can be concealed under the trucks at with the flick of a switch be activated or deactivated. They will also have to stop when they get to the end point without another switch movement (limit switch arrangement)
I have looked at 12v actuators that are used on lift chairs and the like and I know there are air operated units around but we don't have the air system to run them.
Anyone got any ideas?
Thanks
Crispy

 

[Amiers]

Not to be that guy but that sounds like a lot of work to do when you can teach people not to run into the giant wagon brake. That being said I can understand if they are getting in the way for storage when wing space is limited.

You can get floor/wagon brakes that can be inside the platform with the wheels. They look something like this however you will need to atleast get a foot under the wagon to make these work.
http://www.vestilmfg.com/products/mhequip/floor_locks.htm


Personally I would stay away from electric brake but I had to recommend something I would look at 12v actuator kits that can handle the weight of your wagon load.

Example: (don't judge the Walmart link)
https://www.walmart.com/ip/Blk-Heav...nline&wl12=198410700&wl13=&veh=sem#about-item

 

[porkchop]

Pneumatics is the normal way to do this, but I haven't found a cheap air caster system. I could imagine creating something out of short throw electric actuators from someone like McMaster Carr or Progressive Automations, but I don't know of an all in one kit.

 

[Crisp image]

Not to be that guy but that sounds like a lot of work to do when you can teach people not to run into the giant wagon brake. That being said I can understand if they are getting in the way for storage when wing space is limited.

You can get floor/wagon brakes that can be inside the platform with the wheels. They look something like this however you will need to atleast get a foot under the wagon to make these work.
http://www.vestilmfg.com/products/mhequip/floor_locks.htm


Personally I would stay away from electric brake but I had to recommend something I would look at 12v actuator kits that can handle the weight of your wagon load.

Example: (don't judge the Walmart link)
https://www.walmart.com/ip/Blk-Heav...nline&wl12=198410700&wl13=&veh=sem#about-item

Pneumatics is the normal way to do this, but I haven't found a cheap air caster system. I could imagine creating something out of short throw electric actuators from someone like McMaster Carr or Progressive Automations, but I don't know of an all in one kit.

The problem is people cant see in the dark on when they are side stage. While I like the manual floor locks I cant get hidden away easily and still be usable. I have trialed the actuator once and found them ok for lifting the truck with my weight on them but I am not sure of what friction pad could be used to stop them from moving. I modified a 50mm throw to be 25mm throw so that it could go though a block of wood for stability and only be a 2.5sec activation.
It seems that I might keep trying. I was going to try and use only 2 actuators but it might require 4 to lift all the wheels off the ground. Now having said that I still need 6.5in of clearance under the truck to fit them in. Might have to go back to the drawing board and design a jack that is raised and lowered with the actuator on its side therefore reducing the amount of space required underneath. I plan on using LiPo batteries like remote control flying things. Small battery with a large capacity and quick to charge. I have had good results with these for other things like wireless DMX lights.
I will keep you updated as things work!
Regards
Crispy.

 

[Morte615]

Just something to keep in mind with any type of automated system. Make sure it "Fails Safe" if power is removed (or air is removed) and the brake releases is the unit going to move when it shouldn't? And if power is removed and someone leans against the wagon because they have leaned against it for every show for the last 3 weeks, is the wagon going to move and then you have an injury.

 

[Amiers]

The problem is people cant see in the dark on when they are side stage. While I like the manual floor locks I cant get hidden away easily and still be usable.

Wings should never be totally dark. Hang a light or two and paint the wagon brakes neon. 1000x cheaper and easier than building low voltage wagon brakes.

But

If you do build them. I look forward to seeing the progression.

 

[Crisp image]

Good thinking on the fail-safe. If the actuators are out they need power to retract. I guess that if I was using air then it would have to be like truck air brakes (automotive) and when there no air brakes are applied.

As far as being totally dark back stage it never really is but it does have some dark corners and they are mostly silver on the poking out bit so you would think that we should be able to see them. This is why forums are so good for this type of thing because when we ask questions others will say "have you thought about this?" so thanks for your input.

Regards
Crispy

 

[danTt]

Rather than designing an independant system that raises the wagon off its casters, I would consider using the actuators to raise/lower the casters directly. Hinge one side of the caster plate, and use the actuator to position the other side of it. With some clever pulley action you should be able to install the actuators horizontally, keeping the profile smaller.

 

[kicknargel]

A few thoughts:

1) "Technical Design Solutions for Theatre: The Technical Brief Collection Volume 1 1st Edition by Ben Sammler (Editor), Don Harvey (Editor)" contains an article on shop-built pneumatic lift casters using air bladders that are not TOO expensive to build. You don't need any particular air system to run them; any cheap air compressor can charge the systems.

https://www.amazon.com/dp/0240804902/?tag=controlbooth-20
(This book and the other two volumes are also my very favorite industry reads.)

2) If using brakes, I don't like to try to lift the whole unit off its wheels. It requires the brakes to also be structurally adequate to support the whole thing, which they're not designed for. I like a brake with a large surface area that squishes into the floor to prevent motion. You may still get a little wiggle, but the unit won't roll away. For the best stability, retracting the casters is the way to go, so the whole unit frame will land on the floor.

3) If using an electric actuator, my instinct would be to use it to activate some other brake mechanism, similar to the ones shown above. The actuators themselves may not be structurally adequate for the loads (particularly side forces) involved. Just use the actuator to push the handle of a device intended to be a brake.

4) If you invent something cool, please share!