[TowerTalk] Re:PP Motor Rotor, Other Rotator Band Aids

[K7GCO@aol.com]

In a message dated 8/21/00 1:48:01 PM Pacific Daylight Time, km6iu@jps.net 
writes:
<< I have a couple of questions about PP motors - maybe you can help me.
 1] The only mod I know of, to change the rotation speed higher, is to 
machine the
 gears off the output bell gear and pin the differential to the bell gear. 
This
 reduces the gear ratio so it will turn about 10x as fast--hence you run it 
with 12V
 instead of 28V.   Do you know of other ways to increase the speed?? Do they
 decrease the torque as well??

*******Several others has asked the same thing so I'm adding this and other 
info to TT.  This is not a good mod as all the torque is at the beginning and 
the bolts will loosen.  All speed ups decrease the torque but--you still have 
plenty to spare.  They used to advertise that "if the beam stuck it would 
turn the house."  I forgot it was rotating one time at 3/4 RPM and it pulled 
a receiver right out of my window when I left the room.  Watching a receiver 
go up a wall is something you don't see very often.  That cured my of 3/4 RPM 
speeds.  

The 2nd best is to bolt the smaller bell gear below the planetary to the 
planetary.  The center post of this gear has to be cut off about 3/4"above 
that goes up into the planetary.  3 or 4 1/4" flat head bolts are first 
installed near the outside of the bell gear with spacers and lock-tite them.  
The gear torque is much lower here.  Make sure there are no drilling chips 
that get in to the bearings.  Use a drill press although I've done it with a 
hand drill.  It's an easy job if you understand what you are doing.  The 
drill holes are done one at a time making sure to clear the bearings.  Tap 
the holes in the planetary gear through the lower bell gear for 1/4 X 32 
using a #3 drill.  Then drill the bell gear only with a 1/4" inch drill.  
With all the holes tapped and the proper spacers (about 2 washers) in-between 
the 2 gears in place, then disassemble and cut the center post off and 
reassemble.  That's it.  Take it to a machine shop if you're not into these 
fixes.  I may get into modifying them or total rehab jobs later in my own 
"Ham Machine Shop."  I know how to get all the bearings out and even replace 
the balls. 

Water can get by the top oil seal into them if the PP is not properly covered 
and ruins bearings.  Most are inexpensive replacements.  The planetary 
bearings are easy to get out, knock the center race out, clean them up and 
replace the balls and grease them up with a low temperature grease.  The top 
3" bearing gets the water first.  If the rusting isn't too bad just clean it 
up and replace the balls.  The balls are available from the bearing 
suppliers.  It can be a loose fit.  If the clean up removes too much rusted 
metal from the races, larger balls may be needed.  But the next larger size 
requires metal being removed from the 2 races.  New bearings aren't available 
anymore and did cost $175.  I made a jig to hold the outer race in the lathe 
and I used a Dremmel tool with a stone heads to deepen it.  The inner race 
can be held by the outside of the lathe jaws.  Grind it deeper.  It's a long 
job as THAT STEEL IS VERY HARD.  I ruined one Dremmel tool even though I 
would let it cool.  I have a larger hand held high speed grinder and that is 
the one to use.  It may take a couple of stone head grinders as they wear 
down fairly fast on that hard steel.  Actually if there is a way to soften 
the steel by a heating process, that's the way to go.  Does anyone know how 
to do that like with a slow cool?  Since the grooves are much deeper, an 
insertion notch has to be cut in each race for bearing insertion.  It's a bit 
tricky to get the notches just right for fairly easy bearing insertion one at 
a time and not have them jump out in operation.  The balls can be forced in 
the 2 notches as the rings will bend.  Do this over a box to catch the balls 
when taking it apart etc Use 3 balls to check fit initially.  It can be a 
lose fit a few thousandths more than normal when finished as it just takes a 
side thrust at a very low RPM.  Usually the mast thrust bearing takes that.  
The PP will take some downward load but it's best to keep it off.  I use just 
an aluminum friction thrust bearing on the bottom of the mast lubricated as 
the PP has so much extra torque to over come it and with nothing to 
rust--another advantage.  It takes several fitting steps of the ball 
insertions for a test fit but you will get there grinding a little off at a 
time toward the end.  Even with a machinist and a lathe doing this for the 
first time with my jig to hold the outside race, it could be a costly job.  I 
developed the fastest procedure to do it but it still takes some time and may 
modify these later for the hams.  I just did one for Lou Gordon K4UX.  This 
is the only critical bearing.  Other wise you may have to get one from 
another PP Motor.  In the big PP there is a bronze friction bearing with no 
problem.  I had thought of making a bronze replacement for the small PP.  

One technique I may use to solve the water entry by the top oil seal problem 
is to mount the PP upside down outside the tower.  Use a motorcycle chain and 
sprocket wheel gears to couple to the mast in a thrust bearing at the bottom. 
 The chain has to be lubed and covered.  By changing the sprocket gear size 
and ratio you don't have to speed up the PP.  The PP is easy to get out of 
the tower for the first 50 year inspection--it's already out.  If you have a 
small tower you may have to do this even with the small PP.  With it mounted 
in the normal manner be sure to drill a drain hole in the bottom of the motor 
cover bottom.  The DC motor is either bolted to the housing or by a retainer 
ring.  This retainer ring can be a bit tough to get off the first time but 
there are ways to do it for the mechanical types.  Grease it for easy removal 
the next time.  A weathered one can be a real problem but I've salvaged 
several.  I took it to a friends garage and used his cleaning tanks and 
impact wrenches.  He showed me how to take bearings apart--it's easy.

There are things that have to be removed around the output spline gear such 
as a rotational stop when new and even the DC brake below.  I also drill 
drain holes in the housing around this spline gear if any water gets that far 
and around it.  There are holes that have to be plugged on the top housing 
and spline shaft with plugs I make in the lathe and epoxy in place.  The 
spline gear has some short 3/8" screw plugs that have to be screwed in toward 
the center--not out.  A lot of things like this have never been recommended 
in articles.  I'm planning a booklet with many pictures I all already have on 
the conversions, maybe even on a Web Site I will have later.  Even with all 
this it does takes some mechanical skills, a lathe and other tools to do it 
right and fast.  I and others were able to do a lot of this 55 years ago 
without a lathe and before rusted bearings.  M Squared has the follow up 
hardware of cover housing and direction indicator.  There is a private 
individual with some of this also.  There are 4 wires coming out of the 
housing and only 3 are used.  I have a 3rd speed up procedure that is the 
simplest and can be returned to the original configuration for reasons I 
cannot imagine--no on has.  There is a threaded drain hole plug on the side 
of the housing near the bottom.  I leave this out.
   
 2] In lining the gears up to place the bell gear over them -  do the 4 gear
 models have both 0 and 2 on each gear?? - or do they alternate?? ie only 0 
on two
 and only 2 on two???

*******No it had both the "0" & "2" on each gear--which served no useful 
purpose. Alternate the numbers pointing out.  Most have just one set of 
numbers.  

 I am using a Mosfet with a DC supply [ 28V 15A ] to reduce the RPM on 
startup and stop. The Mosfet will restrict the current from 0 to 15 Amps. It 
can be
 controlled with less than a volt with no current drain - hence a pot or 
computer
 can operate it.      Thanks Larry km6iu

*******I have a longer and very complete article on the PP I wrote 8 months 
ago I was going to put on TT without pictures but some complained about long 
Posts--and continue to do so.  So valuable information about how to use the 
greatest rotator of all the PP Motor--never got posted.  I'm probably the 
only one left with all this info and had the desire to share it.  "Excessive 
restrictions" are another example of the misuse of a Reflector with FREE and 
often very expensive INFORMATION by those with "Limited Horizons."  All kinds 
of problems and often "Temporary Band Aids" exist with some of the rotators 
of today that fill TT repeatedly.  Their total length is very very long.  
Properly installed, the PP is trouble free, actually over designed for the 
task and totally advanced in it's usefulness without the 1 RPM restriction 
I've thoroughly enjoyed for 55 years.  I keep trying to make everyone aware 
of these concepts but trying to drag some kicking and screaming into new 
concepts in any area--most of whom have never used one--is a tough task.  
When they finally see it's advantages, a certain look comes over their face 
that looks like they died and just woke up in ham heaven.  I have a Rotating 
Globe Direction Indicator that centers on where you live that is a gem and 
will write up for a mag. 
  
 K7GCO@aol.com wrote:
 > TT:  I accidentally sent the post I hadn't spell checked or had a Subject 
Line.
 >  Disregard it and please use this one.  K7GCO
 >
 >  In a message dated 8/18/00 9:04:04 PM Pacific Daylight Time,
 > 107770.3462@compuserve.com writes >  <<
 >   Just a couple more cents to throw in, would it be possible to pin the 
mast
 >   but use a bolt or whatever that would ultimately shear before too much
 >   stress was put on the rotor?  Not sure how that could be determined but 
it
 >   could be a mechanical fuse to keep from really tearing things up
 >   I recall once trying to pin a mast for no rotation and it was fairly easy
 >   to shear it off without too much force.  73 Jim KI7Y   >>
 >
 >     There are times when "Johnson Mechanical Band Aids" are needed to 
solve a
 > problem.and we all do this at times until we find the final solution.
 > Sometimes the band aids are so good no further change is needed.  Others
 > eventually fail to the point where users and even manufacturers say "that's
 > it and develop or look for the final fix."  Then even proven designs fail 
as
 > ways are found to ruin them.  Firestone comes to mind.  In some areas like
 > rotators and towers this point has not been reached as yet.  Tolerance, 
time
 > and money to waste for bad designs still exists with no sign of a solution
 > insight.  Manufactures of certain ham gear or antennas seems to hinge at
 > the level where Reflectors like TT are needed to cover all the band aids 
and
 > few permanent fixes are ever made even well into the year of 2000.
 >
 >  At the age of 69 I don't have any tolerance, time or money to waste and 
that
 > tends to govern my suggestions hoping to speed up the time when others 
decide
 > they are damn tired of "Just Plain Junk".  Paul Harvey summed it up saying
 > "We live in a "Junk Society".  We have junk cars, junk houses, junk food,
 > junk pills, junk schools, junk books, junk buildings, junk movies, junk 
TV's,
 > junk TV programs, junk radios (antennas, rotator, towers)(the old radio
 > programs are absolutely great) and some cities even have junk people.  They
 > have more suicides than homicides.  There is even junk sex also--it's low 
in
 > Emotional Nutrition and doesn't stick to the ribs.  Yet the largest 
profits are
    somehow still made--on Just Plain Junk.
 >
 >  Now this is the year 2000 and "certain problems" have been around since 
the
 > first yagi was installed over 70 years ago.  Inadequate rotators or any
 > device usually takes awhile to work out the bugs and many "final designs"
 > still continue to be very elusive and no solution or demand of one has 
shown
 > any flicker of light of ever emerging.  Occasionally suggestion are made by
 > those who have solved the problem--over 50 years ago and repeatedly since.
 >
 >  "To Shear or Not To Shear" is the latest pin mast rotator problem plaguing
 > many hams minds on TT today still in the year 2000.  Others even adjust the
 > tension on clam plates to make sure the casting don't eventually crack or 
the
 > mast can slip before damage to the rotator or even the beam in a high wind.
 > It's kind of a "mechanical fuse."  No one has yet to suggest a design that
 > doesn't need all these band aids.  I'd like to see an add saying "Band Aid 
Free"
    for a product in the rotator, tower and antenna area.
 >
 >  At the Dayton Antenna Forum there was a "wind balancing concept" with an
 > additional short element placed the right spot to "wind balance the 
antenna"
 > from any direction.  That should reduce wind torque surges on the mast and
 > rotator.  That's a good idea that I don't even call a band aid as it 
corrects
 > a built in deficiency.
 >
 >  Another band aid on TT was to use a very long mast of about 40' into the
 > tower to take up some rotational torque peaks.
 >
 > Another is the "BMW Cushion" used inbetween the motor and rear transmission
    in the drive shaft. My Porsche doesn't need it.  They strengthened 
everything
    adequately the motor drives.  It's used between the rotator and the mast 
and
    does have some value but it is another band aid.
 >
 >  Then there are all the "brake problems" that go on and on and on like all 
the
      "thrust bearing" problems.
 >
 >  Are you aware many never ever have all these problems.  They use a 
rotator 1
 > to 2 steps larger on purpose than the manufacturer recommends--spend the
 > money.  Or they have Prop-Pitch Motors properly installed as they are the
 > only rotator that is Band Aid Free.  There are basically 2 sizes (a 3rd 
really
 > big one exists) that fit all beams.  If properly installed they seldom ever
 > require maintenance except motor brushes after say 50 years or 2 owners 
full
 > time use.  All my brushes are still good after 55 years use.  Water got in
 > one that I didn't install properly but I've learned how to keep the water 
out
 > and replace or repair all the bearings.  One bearing is no longer 
available.
 > It's a good idea to remove the original oil in it and replace with a low
 > temperature grease.  The oil will slip by the bottom seal and get into the
 > motor.  New seals are available at the top.
 >
 >  PP motors have a 3/4 RPM with 28 VDC.  They will even work with AC voltage
 > but at a lower speed and higher brush and commutator wear.  3 methods have
 > been developed to mechanically speed them up without any mechanical
 > compromises as they can have up to a 9000/1 gear ratio.  I have a PP motor 
on
 > a 2M beam for the speed of rotation.  The first speed up in CQ in about 
1946
 > should not be used other than on light beams.  The 2nd modification shortly
 > after is great.  I came up with one that is the simplest of all and it can 
be
 > returned to normal if ever desired where the 2nd mod cannot.  Once the 
faster
 > speeds are used I know of no one who ever went back to 3/4 or less 
RPM--maybe
 > for a 75M beam.  Due to the very high initial gear ratio even after a speed
 > up, NO BRAKE IS NEEDED.  The only thing that can happen when it is
 > mechanically speeded up is that all those who have never used a PP motor
 > claim is "it can rotate over a period of time to an orientation with less
 > wind stress with a wind unbalanced 40M beam".   Big deal!  These hams would
 > complain if hung with a brand new rope.  This is actually a "desired
 > characteristic" for when one has a 40M wind unbalanced antenna--for those 
who
 > can't see the light. This reduces the mast/tower torque and guy wire
 > stresses.
 >
 >  With a full 28 VDC on them I can get up to 6 RPM.  When I tell other hams 
of
 > this I hear the total nonsense again "it too fast-it will tear up the tower
 > or bream."  For 10M and higher "it's perfect."  I've even use it on a 3
 > element 20M beam on a 24' boom with a long mast in a 20' tower.  The PP 
motor
 > was near the bottom where it removed 95% of the tower from the additional
 > rotational torque.  On a high tower, rotational torque on the tower can be
 > reduced with guy torque arms that are available.  To further explain why
 > speeds above 1 RPM are desirable and very practical, the turning rate
 > accelerates up to the full speed over say 5-25 degrees (1-6 RPM) due to the
 > high gear ratio and momentum of the large PP.  With the larger PP (actually
 > the medium one), it would smoothly coast down to a stop from say 6 RPM over
 > about 90 degrees--less with slower speeds and the smaller PP.  There are 
"no
 > sudden jerks."  You learn to shut it off before you get there.  This is a
 > great rotator concept.  I used to do a lot of F/B checks and loved the 
speed.
 > I can peak an unknown signal except with a 2 element all band quad with the
 > DE's tied together with a real fast or I can nail a known DX station with 
the
 > same antenna with individually fed DE's when I hear him real fast.  Those 
who
 > I demonstrate this to inparticular with a higher gain beam "suddenly see 
the
 > light--or speed light" and demand I convert their PP motors or get them if
 > they don't have them.
 >
 >  One can adjust the speed to the size of the beam.  For example a 7 element
 > 10M beam on a 44' boom, I usually rotated at 3 RPM and will use 5-6 RPM 
with
 > a proper tower torque measures on the tower below the rotator.
 >
 >  I have a way to easily speed up conventional rotators also.   I increase 
the
 > diameter of the small gear on the motor shaft and decreased the size of the
 > adjoining gear of such ratios to get any new rpm I want.  The same shaft to
 > shaft spacing remains.  I frequently use a smaller beam than what it was
 > designed for and have yet to have a problem.   I even speed up the small TV
 > rotators the same way.  4 RPM for even a large TV antenna is no problem.
 >
 >  I did add a great feature of a "stepped voltage switch."  This is not 
needed
 > for PP rotator protection.  I do use a variac to adjust the initial working
 > voltage and speed.  The voltage steps were such that I obtained speed
 > increments of for say a 3 RPM max of 1, 2 or 3---then 3, 2, 1 and 0 RPM per
 > step.  So regardless of the final speed, no more than 1 RPM increase or
 > decrease ever occurred depending on how fast I rotated the stepped switch 
CW
 > or CCW.  I could stop at any speed or change it as desired for "fine
 > turning."  It works like a charm and speeds up all phases of antenna 
pattern
 > measurements and general ham operation.  One DXer who used mine had all his
 > rotators speeded up with the proper design and is trouble free to this
 > day--and very fast.  Manufactures probably won't do this as it would add 
some
 > additional cost to them but it would be a great sales feature for an
 > innovative manufacturer.  Does one exist?
 >
 >  You can still use an "advanced rotator design 55 year old PP rotator" from
 > the last Century with the proper modifications.  M Squared has a kit for
 > proper installation including a direction indicator.  If made today the PP
 > motor would probably cost $4-5000.  The mechanical tolerance control inside
 > was tremendous during WWII manufacture.  I've never seen any variance in 
the
 > fit of all the parts and bearings.  It's the only mechanical device I've
 > worked on where this was true.  Quality control of mechanical tolerances
 > vanished from US manufacturing for many years but was found again in Japan
 > aided by Demming and his efforts.  US manufacturers wouldn't listen to him
 > after the WWII as the US could sell anything it made.  I believe the PP
 > motors were made by Electrolux the Vacuum Sweeper Co. and I still have one 
of
 > their Sweepers.  Does anyone have any manufacturing plans for the PP motor 
or
 > any other background?  I love these rotators.  I used to know the son of 
the
 > owner of Electrolux in Philadelphia back in the 60's--Walter Groff.  He had
 > an interest in guns.  I didn't know then of this connection if my 
information
 > is correct.
 >
 >  If you ever take one apart and remove the planetary gear, there is a trick
 > you have to know or you won't get the bell gear to mesh.  There are some
 > witness marks on the 3 or 4 gear planetary gear like a "0" that have to be
 > all pointing out.  Some of the 4 gear models that have 2 marked with a "0"
 > and 2 with a "2".  Which do you use--the "0" or the "2" all pointing
 > out--neither?  You have to alternate these and I had to find this out the
 > hard way.  I accidentally did it right the first time not knowing what I 
did.
 > Years later I speeded up the motor and could not get the bell gear on with
 > either combo.  How did I get it together before on the first try--blind 
luck.
 >  So as a last try I alternated them and presto--it dropped in place.  
(Most have 
    just one set of numbers)
 >
 >  By the way there are no Band Aid Reflectors for PP motors and other 
properly
 > made antennas like the M Squared ones I've used, Antenna Mart Quads and
 > Raibeams--they don't need any.  When you get the ham license it doesn't 
tell
 > you that beam antennas can grow into an Albatross on your back or actually
 > your tower if not properly installed, cost you a lot of maintenance time 
and
 > money if it's not of the proper design.  Hams incorrectly assume many of 
them
 > will never need any maintenance.  Many antenna problems never get fixed 
over
 > the winter.  Those with big contest antenna sites can spend a lot of time
 > working on them.  Check into the Band Aid List on TT often needed of
 > equipment before you buy it.  It will cost you more than the money you 
think
 > you saved buying it.    K7GCO
 > >>

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