That is a lot of rotational torque coming to a quick stop. I hope you have
a stout tower installation.
What is the rush? I have my controller set to slow down as it approaches
the stop so it lessens the stresses.
"A slip of the foot you may soon recover, but a slip of the tongue you may
never get over." Ben Franklin
[mailto:firstname.lastname@example.org] On Behalf Of Jim Hargrave
Sent: Sunday, February 08, 2009 5:06 PM
Subject: Re: [TowerTalk] Tailtwister not turning, still
> but they have very little torque.
You must be talking about some other type of rotor.
A little more about my Prop Pitch drive. Mine is the small size.
The gearbox is modified to give a 1900:1 gear ratio. The drive motor is
rated at 1/2 HP.
I guarantee you, your pencil would break to shreds and probably take your
hand with it.
I have the power supply set to give me a stop to stop rotation in 20
seconds. The antenna is a TH6DXX HF beam and a 2m - 14 element beam. That
takes a good amount of torque to rotate.
* 73's Jim W5IFP *
>[mailto:email@example.com]On Behalf Of Roger (K8RI)
>Sent: Sunday, February 08, 2009 11:26 PM
>Subject: Re: [TowerTalk] Tailtwister not turning, still
>Jim Hargrave wrote:
>> >Although I saw some one say they run at
>> >several thousand RPM my guess
>> >would be closer to 680 to 800.
>> >The easy was it to count the
>> >number of
>> >poles and do the math.
>> I was the one that made that statement. My reference was to
>the Prop Pitch
>> drive motor, not the Tailtwister. Apples and oranges. Following is the
>Ok, I read it as the Tailtwister.
>> >I am getting ready to "retire" an overloaded Tailtwister
>> >rotator with a "small" prop pitch motor (9,576:1 reduction
>> >ratio) and was wondering about a couple of details in
>> >regards to putting it in service.
>> Now lets do the math. If the output shaft turns @ 1 RPM, then
>I submit that
>> the motor better be turning @ 9,576 RPM. Bear in mind this is
>a series DC
>> motor and basically the rpm is limited by inertia and
>> the target load.
>True about rpm limiting and the RPM for the prop pitch motor. I can
>understand why they went to hydraulics <:-)) Theoretically one
>load would be capable of an infinite RPM, An unloaded series motor with
little friction will run
>fast, Given very little resistance they have to be built fairly sturdy
>so as to not fly apart. The rotator I had apart did not run
>fast at all
>and the motor could easily be stopped by sticking a pencil eraser
>against the rotator. I think die grinders would likely be series wound
>as they run up to 30 or 40,000 RPM.
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