Subject: Twin Gearbox design
From: Rotary Engine
Date: 12/16/2010, 7:26 PM
To: AAA Put this in the To box




  Paul
  I am sending you the last design wich is an idea of George Grimes to
  use regular car engine crankshaft main bearings.
  I was looking to use the main bearing of an 10-540 and the price is
  about $300.00 with taxe and you can buy full set of car bearings for
  $35.00 each.

  I am using 4 set of bearing may be is enought or 5 set may be required.
  I looking to secure the planet with the crankshaft with woodruff
  key set
  at 2 or 4 places or splines, and machine longer small gears shaft
  on the
  planet and insert on crankshaft back plate.
  I can use both side of the trust engine bearing but i need an other
  trust bearing on back of the planet face .
  If i go this way i will have to make a mold for a casting.
  Make a look on it and i am looking for your comments.


  *Jean Prudhomme*

  Very clever idea George. I think this will fly. I am impressed.

  I like it.

  It occurred to me to use the stock Lycoming front bearing shell
  but this is better and cheaper.

  I have added some attached 3D's for this type of PSRU to your three
  dwgs.
  I was just going to get a junk Lycoming crank shaft and cut
  off the cracked back of it :)

  You won't need any castings as the housing is 2 pieces.
  I think it can be done out of billet on an NC mill.

  Paul Lamar


  Paul
  On the first dwg i show a possibility to use the trust on both sides of
  main bearing where the oil pressure inlet tap but we have to allow some
  clearance for the prop shaft expansion what do you think ,but we
  need the
  rear trust bearing to hold the planet in place.
  Your comments on woodruf keyway between planet end shaft and the
  prop shaft do i should go with this or splines wich is more
  machining and
  cost?


  *Jean Prudhomme*


  I would not do either splines or keyways. They are not needed.

  Since you plan on machining the prop flange anyway just
  machine the other end with a flange large enough
  to drill and tap to take the pinion bolts/shafts.
  Off the shelf shoulder bolts will work.

  That is the benefit of having a split housing.

  You can then use a stock Lycoming 2 piece thrust bearing shell.

  BTW folks don't get this constant speed PSRU confused
  with a fixed pitch prop PSRU.


  Paul Lamar


  Paul, I can't locate the drawing I sent to Jean with some thoughts
  about a constant speed hollow shaft redrive but will post it if I find
  it. Possibly Jean still has something as a e-mail attachment or drawing
  and can post that. The basic idea is using 2.75 ID automotive
  mainbearings as used in chrysler hemi and big block Chevrolet. One
  thrust bearing is used as a safety backup for the pair of roller thrust
  bearings. just to keep things going if a thrust bearing fails. There are
  three regular main bearings used with drain lands in the case between
  them. The rear one is for planetary support and the two center ones for
  oil in and out of the hollow prop shaft to allow to be sealed by the
  bearing shells and oil seals beside them. the hollow shaft hs a bulkhead
  left when it is drilled out to hollow it out. An oil feed to the prop
  is drilled to the center of the bulkhead and an "O" ring sealed tube
  from the center of the bulkhead goes out to the prop flange. The prop
  flange is held on the hollow shaft with a large version of a split lock
  as used on automotive valves. This is necessary to allow oil seals and
  "O" rings to be installed over the front of the shaft and to avoid a lot
  of machining on the shaft. We were intending to use a vertically split
  two piece symmetrical housing of 398 aluminum. This was so that only one
  side pattern would be necessary and no casting cores would be required,

  I was intending to use a crank trigger sensor to measure RPM
  and use that to operate a dc variable voltage solenoid driven DO3 sized
  proportional cartridge valve. They are extreme precision valves that
  you screw in a block or manifold and can be as cheap as $29 without the
  solenoid. The oil for the constant speed prop was to come from a tee
  after the oil cooler through a belt drive gerotor pump and go to the
  cartridge manifold which also has two pressure regulator cartridges. A
  high pressure for the prop and a low pressure for redrive
  lubrication.Oil is returned to the engine oil pan.

  As a basic redrive used for a fixed pitch prop it would be no
  lighter than the flight proven design Tracy sells. The advantage would
  be for constant speed and using the transfer case planetary (warner
  4407) a HP capacity for a turbocharged six rotor.

  Jean and his wife stopped by on the way from Canada to Florida so
  I could give him a lesson on how to use Rhino, and we just did the
  redrive as something to draw. A few weeks later I neatened it up into a
  workable design with accurate dimensions for oil seals , "O" rings,and
  bearings etc and sent it to his e-mail. Jean was still at that time
  determined to use inboard mounted engines with 90 degree drives on the
  wings for his scale piaggio project. I will likely design a PSRU based
  on these ideas after getting something done on airframe construction.

  george grimes

  It would be great if I had a Rhino on this. This is all I got
  from Jean. Let me know if you do not get 3 attachments with
  this message.

  Paul Lamar

  Yes Paul i found it there is as attachement
  The complete set from SUMMIT part # MS-829 H HIGH PERFORMANCE TOTAL
  PRICE $79.95 PLUS $9.95 WICH IS A MAIN TRUST BEARING AND 4 REGULAR
BEARINGS
  I revised the Georges drawing and he is right to use only one trust and
  all other as flat bearings it will be much easyer for machining and
  lower cost.


  *Jean Prudhomme*

  OK Jean. Thanks. Why the space between Chevy V8 bearing shells?
  Why not just butt them together?

  Paul Lamar

Each grooved between each bearing act as way out of oil pressure and
faster oil circulation ,the shaft have better support by spacing the
bearings and if we butt them all it can have some spot of lack of
lubrication.
If you look on the 10-540 they do have large grooved for better
lubrification.
One of the groove does not have a way out to hold the gorvernor oil flow
for constant speed prop
I am correcting my sketch with 4 flat bearings and 1 trust bearing
similar as George design

*Jean Prudhomme*


There is one groove at the feed hole in the Lycoming shell.
The oil pressure fed into the front bearing is over 100
psi because that is what the constant speed prop requires.
That oil pressure comes from an auxiliary boost pump
in the prop gov. Normal oil pressure for a piston engine
is only 40 psi.

The long shell heps to retain that 100 psi pressure. If you narrow
the shells that high oil pressure will bleed off around
the edges. If you are going to use the V8 main bearings
I would butt them up to each other to maintain the prop oil
pressure.

Paul Lamar
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