Steve Hunt wrote:
> Roger,
>
> I'm no mechanical engineer - just a lowly communications engineer - but
> I'm trying to understand the point you are making:
>
This arose from the problem of bolts falling out of rotators and trying
to find effective means of preventing that.
> Roger (K8RI) wrote:
>
>> When that nut is tightened it
>> pulls the bolt straight out against the threads in the rotator, or
>> objects base which adds force that adds to the torque required to remove
>> the bolt with out torquing the bolt down tighter.
>>
> Isn't this exactly what happens when you tighten the head on a
> conventional bolt? You turn the head but it can't move forward (because
>
When you tighten a bolt the torque is the vector sum of a rotating ramp
which is divided between rotational and linear forces. The nut exerts
the same forces on the bolt, but where the bolt fits into the case sees
mainly the linear force which is that vector sum converted to linear but
minus friction. (IIRC). They used to run us through these problems in
calc based physics.
HOWEVER the largest weakness of the jam nut as we are talking (Not the
half thick ones) is the effectiveness of using a jam or lock nut depends
very much on the user. Using SS I've had them lock so tight I could not
remove the bolt until the lock nut had been loosened while with new cad
plated bolts (that arrive from the hardware store with a coating of oil)
were almost completely ineffective.
> it's hard up against the washer or whatever) so it pulls the bolt
> against the threads. I would have thought that for the same thread
> pitch, the same torque on the nut or the head would result in the same
> "stretch forces" on the bolt. The jam nut simply locks the first nut to
> the bolt; so I still don't see that the situations are any different.
>
>
Roger (K8RI - ARRL Life Member)
www.rogerhalstead.com
N833R (World's oldest Debonair)
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