> This is all a very good argument for an Alfa-Spid style of controller:
> mast
> slips, adjust the controller. Period. No climbing. No pinning. No stripped
> gears.
>
> (At least until the slippage is, I think, 320 degrees, at which point you
> reach the upper limit of the box's ability to adjust.)
It depens on the original orientation, but I'm assuming the Alpha has 320
degrees of over travel. I have mine oriented N at the middle of rotation on
the Prosistel so I have 60 degrees of over travel in each direction (480
total rotation), but the only time it's been off was when the telescoping
mast bolts sheared.
As fro back driving a dual worm gear motor and starting torque there are
several things required:
Given a high enough ratio the gears will fail before the box can be back
driven. Some where in there as the ratio is lowerd the box can be back
driven, but you have to have enough torque to not only back drive the box,
but what ever is driving it. Some motors are easily spun and some are not.
As far as starting torque that is the starting torque of the motor
multiplied by the gear ratio of the gear reduction box/unit.
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
>
> The Spid uses pulses to tell the controller the antenna's moving, so
> there's no physical connection between the mast and any indicator
> rheostat.
>
>
>
>
>> From: "Al Williams" <alwilliams@olywa.net>
>> Date: 2006/03/01 Wed AM 11:53:28 CST
>> To: <towertalk@contesting.com>
>> Subject: Re: [TowerTalk] Rotor Stripping Gears?
>>
>> A cutaway drawing of the M2 2800 rotator shows five (5) regular type
> gears
>> between the mast clamp/mast and the worm drive!
>> I have noticed that there is a fair amount of movement of the boom
> caused
>> by the wind apparently acting on the backlash of the five gears.
>>
>> The M2 specification lists a braking torque of 17000 in-lbs while also
>> stating that "Precision wormdrive - cannot be reversed by mast torque;
> NO
>> BRAKE RQD. As mentioned by others M2 voids the warranty if the mast
> is
>> pinned to the rotator clamps.
>>
>> Question is, what does M2 really mean by their braking torque and how
> was it
>> determined? Also how does one determine the torque caused by the
> wind load
>> and inertial load of the antenna/mast assembly?
>>
>> Also note that there are two long elements on one side of the mast vs
> only
>> one long element on the other side..
>>
>> k7puc
>>
>> ----- Original Message -----
>> From: "peter.voelpel" <df3kv@t-online.de>
>>
>> I learned it twice that worm-gear drive rotators also loose their gears.
>> Two of my Prosistel PST2051 failed with a beam of 0,9m2 at 10m height
> and
>> only 60km/h wind gusts at that time.
>> The worm axle pushed the bearing completely out of the housing which
>> ruined....
>>
>> _______________________________________________
>>
>>
>>
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>>
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