Ok Paul see attachement
  It will be similar to this photo with straight main spar


  Jean

  That is much better Jean.

  Paul Lamar

  Jean, The pcture was most helpful, and I just thought I might also ad some
 random thoughts. Reguarding the automotive differenial an important thing
 to
 remember is that in a car there is a tranmission ahead of it with something
 like a 3.85 to 1 ratio and maybe a 2.85 ratio second gear multiplying
 torque, the differential  has to be larger due to the resulting increase in
 torque.Also torque  is related to horsepower such that the higher the RPM
 the lower the torque for a given horsepower transmitted. The engine makes
 the torque, we calculate horsepower moe like a conversion factor
 horsepower =torque X RPM/ 5252     That is why torque equals horsepower at
 5252 RPM

 By transmitting your torque at 6000 rpm you are dealing with
 less than 275 pound feet of torque. My Nissan titan pickup  is like 1100
 pound feet into the differental and sized accoringly. As Paul indicated
 weight in your sketch is a concern. I would be looking at shaft drive
 motorcycle rear gearing such as BMW 1100cc or Honda gold wing or valkyrie.

 These are a performance part built as light as possible for performance and
 ow unsprung weight, and run without a cooling system. Also the driveshafts
 are light and may be carbon fibre tubing as is used on som new cars. The
 lower unit of a 250 horsepower mercury or evenrude outboard and sold
 separately on 300 hp and 400 hp hydroplane powerheads have little or no
 gear
 reduction and handle 400 pound feet.

 The problem is that they rely on water
 imersion for cooling and with tracy's 2.85 psru the torque capacity would
 be
 exceeded. Motorcycle stuff loks like manna from heaven for your
 application.
 I don't know a model but a type with a single sided swing arm would likely
 have larger bearings and be easier to mount. You will still need a hollow
 prop shaft with thrust bearings for the thrust load which coul be whateve
 you intend to use on the auto diferntial since the halfshaft couplers
 didn.t
 support a thrust load.

 The corvette I had did take thrust loads since the
 half shafts were the lower control arm.Please keep the newsletter posted on
 what you design. Any ideas you come up with  may help other rotary people.
 Did you do that twin engine velocity model  in the picture?

 george grimes


 You  are quite knowledgeable on this subject George so perhaps you
 would be interested in these PSRU designs.


 Paul Lamar



 Paul, thanks for the pictures. Possibly my wife knows how to make us some
jpeg screenshots.I prefer to send you solid scle models that dimensions can
be pulled off of if desired and you can spin them around to ge alternate
views if something is not clear.I will be starting up hat computer this
afternoon, just had to check the newsletter first.

george grimes

What format are the solid scale models in?
So far ACAD dxf has not been working out as  apparently it was developed for 2D
drawing files. IGES, STP, Solid Works native or Rhino native are
all interchangeable. Rhino has over a dozen  format types both export and
import. I assume Solid Works does the same. My Rhino stp or step files load
directly into Master Cam. Master Cam outputs G code programs for NC mills
and lathes. Takes about 30 seconds for the Rhino or SW design to get into
a NC tool that then proceeds to machine the part. Same goes for casting patterns.

BTW here are a couple of 3D's of a tube shaft PSRU that cuts the weight of Tracy's PSRU
by 15 to 20 pounds using the same Ford 6 pinion gear set. It is designed to
adapt to a stock low weight high pressure die cast bell housing.


Paul Lamar