Is there any reason why the particular gear ratio between the rotor and the
 output shaft (not sure if this is the proper term) was chosen?  Would there
 be a way to modify this so that the PSRU was essentially integrated into
 the
 motor?  So, for example, so that 4 turns of the rotor were necessary for
 one
 turn of the shaft instead of 2?

 Just a thought, but might save alot of weight and one of the major risk
 factors of auto conversions.

 Thanks,
 Brannon

 I am not sure what you mean by "integrated".
 Can you come up with a sketch?

 Paul Lamar


 Brannon,   The PSRU ratio ideally is the engine RPM at max power for take
 off devided by the RPM where the prop tips are going supersonic. The next
 factor is that in our case we don't particularly want the added weight of
 offsetting the thrust line above the E-shaft center. The planetary gear
 arrangement puts the output shaft directly in line with the e_shaft with the
 added benefit of driving through 6 planet gears for a minimum of 6 teeth
 transmitting the power rather than one tooth on a gear to gear drive. There
 is also a lot  of cumulative line contact on the gears with the planetary,
 therefore a relatively small gearset can be used. The gearset of choice is
 from Real World Solutions designed by Tracy Crook. This PSRU uses
 a superduty ford diesel (E40D) low range planetary which happens to be 2.85
 ratio  when the ring gear is held and the planetary drives the prop Holding
 the ring gear also turns the prop the same direction as the engine rather
 than reversing the rotation allowing a larger selection of props to use..
 Ideally  we could use more gearing in the range of 3.20 to 1   but to use
 mass produced gearsets we have to choose something commonly available.  In
 my case (6 Rotor) I need a larger gearbox for 700 HP and after looking at
 photographs of planetary gearsets for sale on E-bay I chose the 4 wheel
 drive transfer case planetary from the same superduty Ford F350
 transmission. The ratio is 2.64 to one. More gear would be better, however,
 this gearset needs no machining off of extra parts  and is well supported
 with bearings. It is also 4 pounds heavier than the E40D but I  can't
 compare the weight of something not strong enough with something that is
 overkill. This planetary is only used when the 4-wheel drive is in low lock
 so even used there are very few hours of operation on the parts. I bought my
 set for $45 and it looks like new. I entered all the Ford parts in Rhino4
 last weekend and am designing the housing next weekend. I still don't have
 the shaft mounted oil pump that fits around the input shaft in the truck
 which I will use for pressure lubrication after running the oil through a
 cooler. This will allow useing gear lube in the PSRU rather than engine oil.
 I well attempt to attach a JPEG image of the Rhino4 drawing showing the Ford
 parts and the thin wall prop shaft designed to use this gearset. All drive
 is thru splines including one that has to be cut near the end of the
 propshaft The rest of the splines are used as is..The JPEG named geartrane
 shows the Ford parts which are used as they come out of the truck. The JPEG
 named PSRU componets includes the propshaft as well as the parts assembled
 for use. In both images there are two lineups of the parts showing the view
 from both ends.


 george grimes