[TowerTalk] Tower limit switches

[K0DAN]

Ed...I'll send you some pix direct & off-list.

The factory install (Tri-Ex) has the upper limit switch mounted near the top 
of the LOWER tower section...so the switch is accessible (about 25' above 
ground)...since all four tower sections move proportionately, the upper 
limit needs only be activated when the next-to-last section gets near the 
end of its upward travel.

The original factory install had the upper limit switch mounted to a C-clamp 
which encircled an upper tower leg. In my case the clamp eventually got bent 
& mis-shaped where it wouldn't stay put, and when I tried substituting 
U-bolts and other hardware, they'd interere with the proper movement of the 
tower sections (there's only about 1/4" clearance between sections).  I 
tried different bults, shims, you name it...for a simple adjustment, I 
couldn't get it to work or stay in place. Eventually I got about 1/2 dozen 
big/thick/black cable ties and and just strapped the switch in place, then 
fine-adjusted the rocker arm for proper travel. The cable ties are 
multi-redundant, and if the whole switch goes away there's also a mechanical 
stop between the tower sections to prevent runaway (if this happened it'd 
probably cause the motor to blow its fuse). As final safety, I never raise 
or lower the tower in the blind...I'm either out at the tower watching & 
listening, or if I remote it from the shack I watch out the window and have 
a remote audio amp listening to the sounds of the motor and cables. Am in 
the process of putting CCTV + audio on the cable drum and motor pulley.

IIRC the list price of most of these A.B./Square-D switches is around $100, 
but if you shop around you can find them for 1/2 that.

Watch for my pix.

73

Dan
K0DAN



----- Original Message ----- 
From: "Ed Magnuson" <w1mag at bellatlantic.net>
To: "Mike" <noddy1211 at sbcglobal.net>; <towertalk at contesting.com>
Sent: Friday, January 07, 2011 1:25 PM
Subject: Re: [TowerTalk] MCL-100 limit switches


> Thanks for the great tips, Dan, Mike and Jim. I'm sure I can run one of
> those switches down now with this info. May start with Grainger. Will 
> check
> out Allen-Bradley switches, too. And Dan, if you have a photo in hand of 
> the
> upper limit switch installation on your tower, please email it to me
> off-list.
>
> It could be that only the pivot arm is out of place. The electrician and I
> had trouble seeing how it should be positioned and what it catches on to
> trigger it. A close-up pix could really help.
>
> I had realigned the lower limit switch to get it working after a tilt-over
> of the tower. But I have a bum leg and cannot climb ladders or towers any
> more to inspect that top one, even though it is less than 20-ft off ground
> when the tower is retracted.
>
> OK, thanks guys. This project may wait until Spring when it stops snowing
> and blowing cold at my country shack along the NY-MA border. So no rush. 
> Hi.
>
> 73, Ed W1MAG
>
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