Paul.
We are back from Kyoto now. It was a nice autumn this year.
Say I have heard about the Ford PSRU and its ability to handle 650
ft.lbs
of torque many times now. No doubt the gear sets are robust but with all
due respect is that statement 100% accurate? Perhaps the Ford set that
Ross and Tracy selected doesn't see all of that torque but just part of it
since it is embedded in a power train with loads in series and in
parallel.
The trucks' rear end would be series while some load paths in the
transmission appear to function in parallel.
About the bearing and planetary speeds of the Bell, I agree with you 100%.
Gear line speeds seem to be within the realm of possibility but
centrifugal
loading is a challenge. Obviously Mistral came up a bearing solution.
Both Bell and Mistral are well engineered products, with each component
selected for use using proven aviation tough components and developed
with
extensive. For the majority of the people on this newsletter though
Tracy's
unit appears to be sized just fine. It is a quality item but is limited to
fixed wood props. I happen to personally think a 3:1 or a slightly higher
ratio has some advantageous for my particular application. Still because
Bell's design point was originally focused on helicopters I look at the
design as a good starting point, not the finished product.
Here are a few pictures of all of the components shot from both sides.
Only the inner race of the TRW thrust and support bearing is shown in the
upper left. No prop shaft is made yet.
Note the planetary gear shaft has a hard bearing sleeve that slips over
it
and then the bearings ride between this sleeve and the inner part of the
gear. This set-up lowers the rpms the roller bearings actually see
because
the sleeve is also moving in relationship to the shaft.
Is that analogous to your stacking thrust bearings?
George
The 'one inch' referred to the thickness of the gears. Yes gear line
contact would be less than the Ford helical gears and spurs are noisier
but
I don't want to have to deal with thrusting issues. I doubt noise will be
a
concern though as it will be masked by greater engine noises.
I haven't seen the gear sizes of the primary planetary that feeds into the
one I have. You can see a cut off plate of the primary planet set on the
left in the picture. Its' shafts are 14.5 mm in diameter and the
planetary
set diameter is about 144.5mm + 0.2 - 0 on shaft center.
Doug Fir
That pretty lady is with a strange looking Japanese gentleman :)
Paul Lamar
Doug,
Some questions please!
The ring gear seems integral to the Bell Housing is that a press - fit?
The piece to the right of that seems like the seal holder cover plate to the
front of the Bell Housing.
The large ring looks like a spacer ?
Below that is the planetary gears and gear holder.
To the left of that is the sun gear I assume?
The 3 items to the left have me puzzled - what is a cut-off plate, is that
one side of the other planetary gear holder?
The bearing is for ?
The center piece of those 3 items is power in? power out?
Also what is that part that is just showing to the right of the picture?
I have this ratio work sheet for you, if you send me your e-mail address
again!
George ( down under)
I forgot to answer some of your questions Doug. All gear sets
in a auto transmission of the Ford type in question are in series
and not parallel. In fact the first set in the chain sees more
than 650 foot pounds because there is a torque converter ahead of
it. The torque converter, at stall, can multiply the torque up
to a factor of two. In other words the very first set of planetaries
(there are as many as three in series) sees as much as 1300 foot
pounds and every set after that see more depending on the reduction
ratio. The amount of torque load depends on the weight of the truck,
the load in the bed, the grade, the acceleration and the towing load.
If the bed load is 3/4 of a ton or 1500 pounds and the truck
weighs 4000 pounds empty with 1500 pounds on the rear the torque
going into the third member could be as much as 1100 foot pounds
or more depending on the rest of the additive factors.
The most torque Tracy and Ross boxes behind a side port NA rotary
will be about 160 foot pounds. 240 pounds for a side port NA 3 rotor
and probably around 300 ft pound for a p-port 3 rotor.
It is easy enough to test. Lock down the Ford planet carrier
on a test stand and connect a long lever to the sun gear. Apply
weight to the end of the lever until the planetary fails.
I'll wager it will take well over a 1000 foot pounds to
break it. That is 200 pounds on the end of a five foot lever.
Paul Lamar ...No rotor no motor.
Paul,
Thanks for the concise and clear explanation.
Strange gentleman with Michiwa:)
AKA Doug (in Japan)
BTW back in the late sixties the standard test for a GM automatic
was to spin the tire in first gear for a few seconds and without
stopping jerk the lever into reverse and spin the tire in reverse
for a few seconds. Repeat 8 to 10 times without stopping. If the
transmission did not fall out on the ground everything was OK.
These were not your modern day wimpy four cylinder engines.
These were hairy chested 400 and 500 cubic inch V8's with 400 to
450 foot pounds of torque. This is about five or ten years after
the Ford C6 got its start.
I was doing over 100 MPH on El Mirage dry lake doing some
aerodynamic testing for Pontiac on the 1971 Firebird TransAm
and I in inadvertently pulled it into reverse. I nearly lost it
but I immediately realized what had happened and recovered by
slipping it into neutral.
Paul Lamar ...No rotor no motor.
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