linear actuators

[IMBEJames]

So I'm looking into fabricating some kind of articulated antenna "tower" to mount on the top of a box truck. I have the design kind of worked out, and it seems like it is going to be a solid, weatherproof design. The one component I am missing though, is a couple linear actuators. I want to stay away from using anything hydraulic, just because we can use less parts and probably have better control over the limits.

Does anyone know of a good source for them? I have one kicking around, it's a Linak with a 6000N push rating, but it has built-in, non-adjustable limit switches and it is slower than death.

I'd like to find something similar, but faster with adjustable limits. I can set limit switches externally, but the less stuff there is to get clobbered by the wonderful New England weather, the better.

And if anyone has done anything like this and has any ideas, PLEASE let me know. I am definitely open to suggestions.

thanks
-jamie

[spareparts]

So I'm looking into fabricating some kind of articulated antenna "tower" to mount on the top of a box truck. I have the design kind of worked out, and it seems like it is going to be a solid, weatherproof design. The one component I am missing though, is a couple linear actuators.

Jamie,
Couple of questions:
What power options (12/24 VDC 110AC, compressed air, etc) do you have?
What is the direction of travel (push or pull)
Force required (N or pounds)
Lenth of stroke
Weatherproof or submersible?
Duty Cycle?
Speed over stroke (stop to stop in "X" seconds)
Termination (pad, clevis, ball end, etc)

Martin

[IMBEJames]

What power options (12/24 VDC 110AC, compressed air, etc) do you have?

I can potentially run an air line to it, but would prefer it to be 12VDC. We definitely have enough air (we have the biggest compressor/storage we could get in order to run the WillBurt light tower).

What is the direction of travel (push or pull)

Both. Pull strength isn't important (primarily it would be pushing a load, but I do need it to pull at least a couple pounds), but it would need to go both ways. The only reason it would need to pull would be to lock it in a stowed position. Ill see about postng some diagrams of what I have in mind. Tough to explain.

Force required (N or pounds)

Probably around 500lb pounds to lift the tower, and maybe a hundred or so to move the antennas (Also taking into consideration the wind load)

Lenth of stroke

This I'm not too sure about. I guess it depends on the weight of the thing when it's done (I havent figured that far ahead yet) but the base of the antennas will be about 8 feet from the pivot point at the base of the tower, so something that can hold that and remain sturdy. The one to move the antennas can be 6-10".

Weatherproof or submersible?

Weatherproof. Enough to withstand driving rain.

Duty Cycle?

Not too worried about that. They will be used to raise the tower for an extended incident, then lower it a few hours later.

Speed over stroke (stop to stop in "X" seconds)

I'd say around 10 seconds or so. The Linak I have here takes a good 30 seconds or so. So faster than that would be nice.

Termination (pad, clevis, ball end, etc)

Clevis would suit my needs just fine...


Thanks!
-jamie

[spareparts]

Lenth of stroke

This I'm not too sure about. I guess it depends on the weight of the thing when it's done (I havent figured that far ahead yet) but the base of the antennas will be about 8 feet from the pivot point at the base of the tower, so something that can hold that and remain sturdy. The one to move the antennas can be 6-10".

8 feet on the lift & 10 inches on the antenna positioner? The smaller one is no problem. http://www.surpluscenter.com has a bunch in AC and DC.

http://www.nookindustries.com/CCactuato ... orHome.cfm has them in stock lenths to 3 feet. They can make them longer as a custom item.

[IMBEJames]

Just an update...

In order to cut cost a little bit (steel is getting just as expensive as the actuators), we changed the design completely. Simple steel frame that lifts to 4 1/2 feet but stows a little less than 6 inches high. Very rugged, and just one actuator.

Thanks to everyone for your insight. It's not primed or painted yet and the antennas havent been delivered, but I'll post pics as soon as I can.

[Code3Response]

Please do, this will be interesting to see.

[IMBEJames]

So the fabrication is just about done. Some of the welds need to be cleaned up a bit, and some of the antenna mounts have changed since the pics were taken.

The fiberglass antennas were just stuck in there for the pictures... But you should get an idea of what we did.

Should be done soon, and I'll update the pics as things happen.

http://pg.photos.yahoo.com/ph/jreems2/a ... /my_photos

[Will]

Neat, that is what I would call a "tilt up"..

[gws]

QST ran an article about using linear actuators to raise and lower a HF vertical mounted on top of a motor home. They used a lever action so the pull would move the antenna vertical.

[IMBEJames]

Well, in the past couple days we finally mounted the "tower." Everything works better than expected, the only thing left is a little touch-up paint where I chipped the enamel...

Of course, the rain started an hour into the install. It was cold and wet, but we did find out that everything truly is water-tight. The whole setup ended up being much more solid than I could have hoped for, we had some good wind the past couple days and we noticed very little movement. As long as the operators don't extend the tower near overhead obstructions, it should last a while.

I'll let the pics speak for themselves, any questions, just ask. Comments always welcome too.

http://pg.photos.yahoo.com/ph/jreems2/a ... /my_photos

I have to say the night shot is by far my favorite.

[NickH]

It's nice to see you removed the broken ladder before you snapped the pics...

[IMBEJames]

Yeah, thanks for that, Nick It was only one rung. No big deal. The shorter one was easier to put up anyway.