Ed, here is that PSRU gear data.

Paul Lamar



I had a whole hour to think, while driving back from Ventura, about the
idea of cutting the planet cage onto one end of the prop shaft. Can't
think of any good reason why we should not do that. I think the od of
the 7075 shaft material we intended to use for the steel planet may be
slightly too small.The only added issue is the potential need for longer
planet shafts to give them greater depth in the alum cage/shaft. I guess
that means I can use the 6 planet gears from the unit I left with you
today and forget about doing the edm or finding special bolts.

The center shaft (pn#675 Makco) you had in your box could be used for
the link to the modified forward drum. This will make getting parts
simple because they all come from the same source. What we might do is
machine the teeth down to our preferred od of the small end of the sun
gear in order to slip a steel tube over it, and use a smaller tube to
slip into the id of the same sun gear. This way the sun gear is slipped
in between the two tubes thereby doubling the shear strength of the hold
pins; while also lowering weight. The two tubes would be welded to the
trimmed end of the modified center shaft.

Ed Carver

Better get a quote on the job first. The planet shafts are not easy
or cheap.

Paul Lamar



I might have a couple thing going for me on this. The planets apparently
have different shaft sizes for different trannys. I need to learn which
size might be most readily available. How should I go about getting the
pins out of the planet shafts so the shafts can be precisely measured?
Screw a tap into them and pull them?

Ed Carver


So far all the front planets I have all have the same .440 shafts
more or less. There is room for a 5/16 EDM.

The area of a 5/16th bolt is .0767 so max clamping load per bolt is
7,670 pounds. 46,020 pounds total for six. Using Murray's statement
about the clamping load doing all the coupling and figuring a coeff.
of friction of only .1. the outer 1/2 inch width  of the planet 4
inch diameter carrier is about six square inches. That would give a
torque of about 4,600 x 2 or 9200 inch pounds or 766 foot pounds. No
help from bolt shear.

Steel on steel coef. of friction is actually higher than .1. As I
recall for locomotives it is about .7 so we might be looking at as
much as 5360 foot pounds.

In addition Grade 8 bolts have a proof load of 120,000 psi and not
100,000 so there is another 20%. No help from bolt shear.


Paul Lamar


I've sort of assumed we would use grade 12 or better. I believe rod
bolts are at least that. If I have any worry about bolting, it is
preventing them from backing out, or pulling the alum threads out. I can
see using the nord lock fastening system to solve that problem, and
wiring with loctite, plus maybe thread inserts in the alum shaft. A lot
depends on how hot it will all get.

Ed Carver

Drilled heads and safety wire. If you can find shafts and afford an
integral aluminum planet carrier that would be a real cool solution.
We need to figure out how to retain the shafts without the roll pins so
it can be repaired.

Paul Lamar


Ed, I just figured out two good reasons to not do an integral planet
carrier. When Ford went to six pinions they also went to a steel
planet carrier. The problem with an aluminum planet carrier is the
planet gears get closer to the steel ring gear and further away from
the steel sun gear with higher temperatures.

The other downside is the 5/16th bolts now lock the back bearing to
the prop shaft. The back bearing will then take all the prop thrust
load.


Paul Lamar



Spreading the thrust load to both bearings is part of the puzzle. The
prop end back bearing needs to push the front bearing to share the load.
The load is transfered via the shaft directly, or via a tube between them.

Is our preferred alum shaft material going to expand beyond tolerance?

Ed Carver

I don't really think sharing the trust load is possible with two widely spaced bearings.

If one bearing is not up to it use two back to back near the planet carrier. I think one bearing can do it. 99% of the time there is no radial load on the bearings at all. It is all axial or thrust loads.

Paul Lamar