Date: Thu, 21 Sep 2017 07:15:57 -0500
From: Patrick Greenlee <patrick_g@windstream.net>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] New to Group, WTB M2 OR2800PX and Rohn TB4
Thrust
<Many of us go bargain shopping and install marginal equipment. Those
<choosing professionally re-purposed prop pitch motors such as those
<provided by Kurt Andress complain less as they have little opportunity
<to do so. Installations of equipment on your (below mentioned) list are
<not the majority topics for a couple reasons: 1.? They don't fail as
<often and 2. They constitute a small minority of installations.
<The above is my personal opinion.? YMMV
<Patrick??????? NJ5G
On 9/21/2017 6:36 AM, Clay Autery wrote:
> Curious why folks don't talk about the AlphaSpid RAK and BIG RAK
> more....? These seem to be the answer to torque, braking, and mast
> clamping...
>
## Rating rotors in....INCH lbs of torque seems silly to me at best.
Take the INCH lb tq rating.....then divide it by 12 to get reality... IE:
FOOT lbs of Torque.
## IE: ham-4 800 inch lbs = 67 ft lbs.
T2X 1000 inch lbs = 83 ft lbs.
OR-2800 2800 inch lbs = 233 ft lbs.
K7NV small prop pitch = 14,400 inch lbs = 1200 ft lbs.
## Envision your boom as two torque wrenchs..back to back. With any
difference in the length of each side produces a huge tq imbalance. Thats
like dragging a parachute behind your car at 90 mph, then wondering why you
require
triple the HP to do the job.
## The RAK and Big RAK have loads of TQ, but at times they become tricky to
install inside
some tower tops. If you have ever played with a 2 ft long TQ wrench, you
will rapidly come to the
conclusion that 100-150 ft lbs of tq is not very much in the grand scheme of
things.
## Braking capability is another issue. Although the worm gear is superb for
this purpose, the
worm gear is at the wrong end of the food chain. The tq is all taken up
initially by the complete
gear train. At least with the brake wedge, its at the output mast end.
## Most of these mast clamps are a joke. The custom 2 inch mast clamp that
came with my K7NV small prop
pitch just barely takes a 2 inch OD mast. Just pinch the flanges with vice
grips..and it wont budge ! The surface area
is immense... like 36 square inchs. K7NV will make the mast clamp for any mast
diameter you want. The 3 inch
mast clamp will provide for 54 square inches of surface area. His mast clamp
consists of a hollow steel tube, split
down the middle, and welded flanges on either sidle of the slit. 5 x bolts
used to pinch the 2 x flanges together.
You barely have 1 square inch of actual contact area with the m2 OR-2800 mast
clamp. The K7NV version of a mast
clamp for the OR-2800 is a real treat. he will make em for any diameter mast
you want. BUT they will only work with
that one exact size OD mast. However, you could use his 2 inch mast clamp
on a 1.9 OD mast by inserting a .050
wall shim around the bottom 6 inchs of 1.9 OD mast.
Jim VE7RF
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