[TowerTalk] Building a Tower Trailer

AD5VJ Bob rtnmi at sbcglobal.net
Mon Jun 26 18:12:11 EDT 2006

 We used one for the Parker County ARC field day event and I can tell you it was really neat to work with.

All it took was two very small motors and a couple of winches for what we had to work with and mounted to it up went the three
element tribander.

Here is a pic or two of the event:

  73 fer nw,

10X# 37210, FP#-1141
SMIRK#-5177, RARS #-149

> -----Original Message-----
> From: towertalk-bounces at contesting.com 
> [mailto:towertalk-bounces at contesting.com] On Behalf Of Jim Lux
> Sent: Monday, June 26, 2006 3:42 PM
> To: Kelly Johnson; towertalk at contesting.com
> Subject: Re: [TowerTalk] Building a Tower Trailer
> At 12:32 PM 6/26/2006, Kelly Johnson wrote:
> >I would like to mount a Force12 LPT tower on a trailer.  Anyone have 
> >any experience building a trailer for a tower (or otherwise)?  I am 
> >looking for design/construction tips.  In particular, I need 
> a trailer 
> >that is small and reasonably inexpensive.  In particular, I 
> would like 
> >the trailer to be as narrow as possible yet still stable enough for 
> >towing.  I'm thinking something with retractable/removable struts.
> We have a couple tower trailers we've used for FD ops at the 
> JPLARC/CITARC operation.  Both were essentially homegrown..
> Here's some comments, for what they are worth..
> Consider using a hydraulic ram to push the tower vertical.  
> By the time you fool with pulleys, lift arms, winches, etc., 
> you'll wish for the simplicity of hydraulics.  You can use 
> inexpensive ag cylinders/rams (about $100 each, brand new) 
> like they use on tractors, and a small electric motor driven 
> pump.  Look at the gear sold to put snowplow blades on pickup 
> trucks, for instance.
> Big advantage of hydraulics: you can limit the speed it 
> moves: in both directions.  No sudden, whoops there it goes 
> over the balance point.
> If you have a crankup style tower, you can get a hydraulic 
> motor to run the winch.  Hydraulics are wonderful this way.. 
> by selecting the different displacements in the pump/motor, 
> you essentially get gearing for free.
> The CITARC trailer has a boat winch type hoisting apparatus, and it's
> *exciting* every time the mast goes up and down, for a whole 
> raft of reasons.
> You WILL need outriggers to make it stable in any sort of 
> wind.  You can 
> make them telescoped (we have a series of 4' nested sections 
> of square 
> steel tubing, but it takes a while to unnest, put them into 
> the sockets, 
> drop the pins, etc.  And then you still have to fool around 
> with jacking 
> and tensioning them appropriately.  Some sort of hinge 
> arrangement seems a 
> good idea, and isn't much more complex to build, IF you have 
> someone around 
> to do the welding..
> Even with outriggers, odds are you'll need temporary guying 
> anyway, so, do 
> some analysis and don't make your outriggers bigger than they 
> need to be.
> Find a good welder to work with.
> Make sure the CG of the system is low when the mast is in the stowed 
> position.  W4EF can tell you some hair raising stories about the 
> instability of the CITARC trailer on the freeway, largely due to 
> underdamping of a high CG (the tower sits a good 6 feet off 
> the ground in 
> the horizontal position) interacting with the tow vehicle and the 
> aerodynamic forces (which are considerable at 60 mi/hr).
> You need some sort of positive lock to hold the tower in place after 
> erection. The lock should not involve reaching into somewhere 
> to insert a 
> pin in a close tolerance hole.
> Assume that the tower WILL get bent sooner or later, and 
> you're still going 
> to need to get it retracted and stowed.
> You need some big "footpad" plates to spread the loads of 
> your jacks and 
> outriggers.  You need somewhere to store those plates on the 
> trailer, where 
> they're not buried under tons of stuff.  Think about the sequence of 
> stopping, pull the plates out, run down the jacks, unhook the 
> tow vehicle, 
> deploy the outriggers, etc.
> Consider storage of stuff on the trailer.  You need a way to 
> secure it to 
> the trailer so it a)doesn't fall off when towing and b) 
> doesn't get stolen 
> off the trailer when it's stored/parked/unattended.  It's 
> also nice if you 
> don't always have to be reaching down into bins or climbing up on the 
> trailer to get at stuff.
> It's definitely worth looking at what grips/gaffers in the 
> movie business 
> use. They spend a lot of time and energy lugging heavy stuff 
> around on 
> locations.  Check out things like "taco carts" and "cable 
> dollies".  The 
> former are nifty rolling carts with slots/cubbies that 
> exactly fit standard 
> plastic tote bins, and a bar across the front to hold them in.
> Consider where your generator(s) are going to be located on 
> the trailer, 
> and that they can be run with the tower up or down (or, for 
> that matter, 
> providing power to move the tower).  Power distro panels are also 
> nice.  Cable trays and guides keep you from severing that coax at an 
> inopportune time.
> >My LPT1242 worked out extremely well for FD this past weekend.  I'm
> >hoping to make it even more convenient by mounting it on a trailer.
> >Unfortunately, I have limited space at my home for a trailer and thus
> >need it to be small, narrow, and light enough that I can 
> push it along
> >the side of my house into the back yard.
> >
> >Any advice would be appreciated.
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