On 1/27/2011 10:56 PM, Mike wrote:
> Nice photos and description Roger, it does not look like a job for the Faint
> of Heart though : -)
Agreed. I've found myself talking more than one through the steps. A
mistake could easily break something expensive.
73
Roger (K8RI)
> Mike, K6BR
>
> -----Original Message-----
>
>
> On 1/27/2011 8:55 PM, Andy GD0TEP wrote:
>> Hi to the group,
>>
>>
>>
>> My PST61 recently failed. It appears that the mighty large rotator has
> what
>> IMHO is a inherent weakness, this being the way the rotator is bolted to
> the
>> bottom mounting casting. Mine is only a couple of years old but has had
>> little use, but the four M8 machine screws that hold the two halves of the
>> assembly have sheared off. As a picture is 1,000 words, have a look here:
>> http://gd0tep.com/rotator/pst61.htm
>>
>>
>>
>> I was wondering if anyone on here has ever taken one of these rotators
> apart
>> before? I'm currently trying to acquire information on how to dismantle
> the
>> rotator from Prosistel in Italy, but so far, no joy.
> Rebuilding the old style PST-61 http://www.rogerhalstead.com/Gears.htm
> Looking at the photos should tell you if this PST-61 is close to being
> like yours.
>
> They may have some differences but so far I've been told the new and old
> housing are similar.
> Externally that PST-61 sure looks different than the one I took apart.
> On the link above photos 25 through 30 give a good look at the side of
> the PST-61 showing the bottom casting bolted to the body. I believe it
> uses 9 M6 Allen Cap screws. The only 4 bolt holes are on the top of
> mine. The base is part of a casting that bolts to the body. The seals
> and bearings should be available at most automotive stores although you
> might have to settle for a single lip instead of double. OTOH I don't
> know what you have available there.
>
> The new ones have a DC motor that is longer and smaller in diameter than
> the AC motor. The few with the DC motor I've seen were very much like
> the one shown being repaired. The AC motor and be mounted vertically or
> horizontally (left or right). You'll note I used white Lithium grease
> instead of the original gear lube. I understand they have gone to using
> the grease instead of gear lube.
>
> "It appears" that the top plate which does have the 4 M8 bolt holes
> (Photo 19) has been used as the bottom plate with a casting mounted to
> it, replacing one piece with two. If that is what happened you *might*
> be able to replace the two pieces with the one...IF it will fit the body
> of yours.
>
>> It's a little worrying that such a mighty rotator relies on four M8
> screws,
>> and as each half of the castings have no castellations or other such
>> fixings, the 4 screws have to take ALL of the rotator torque.
> It appears the screws may not have been torqued down, or were soft. A
> grade 5 M8 can hold a lot of force in the shear mode. OTOH the ones
> I've seen with the one part base all use 9 M6 SS Allen Cap screws. Then
> again it's possible they sell/sold a slightly different model over here.
>
> The positive side is you are a lot closer to France than I am. I found,
> getting parts from the factory took a very long time and that big brass
> worm gear wheel is expensive. (Photo 16)
>> Anyone with some info to hand?
> If I can be of help let me know.
>
> 73
>
> Roger (K8RI)
>>
>> 73,
>>
>> Andy
>>
>> http://gd0tep.com
>>
>>
>>
>>
>>
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