Finn Lassen wrote:
I'm considering selling my RV-3, buying a boat and using the Ross drive
as an anchor.
Seriously, I'm going to try to fix the Ross drive at the lowest cost
possible.
My current plan is to use a 2" long sun gear, get the input shaft turned
down from 1.44" to 35mm to fit the thrust bearing Tracy is using. Make a
simple 3/8" alu plate for the thrust bearing to rest on and to hold the
oil seal. I think I may even be able to avoid machining the rear of the
bell housing bulkhead by using the mounting bolts to adjust the thrust
plate 90 degrees to the shaft (plenty of RTV or a silicone baffle
material mat between bulkhead and plate).
Finn, Make a drawing of this. If you do, I think you will see that the
plate section supporting the bearing will bee too thin after putting in the
counterbore for the seal. I would also encourage you to machine flat the
bellhousing instead of the "adjustable" setup. Too many things can go wrong
there.
Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com
I agree, even a 1/2" plate looks marginal with an 8 mm thick seal. Might want to
try a 4 mm thick seal. BTW I couldn't find the seal number you gave me on the SKF
web site.
I'd like to find a suitable thrust bearing and seal with 1.44" ID, so I don't have
to get the input shaft machined down.
The "adjustable" setup is far from elegant but I don't have the machinery to
accurately machine the back of the bell housing bulkhead.
What kind of force can I expect the plate (and bolts) to see from the thrust
bearing? 700 pounds x 2.17 ~ 1500 pounds?
If someone offered me $1,500 or more right now for my Ross drive (and starter), I
think I'd take it and buy a drive from you, even though I'd have to move the left
radiator 3/4" forward and make new oil cooler brackets.
Finn
The helical gear thrust formula is T = F * TAN(helix angle)
F is the tangential force and T is the thrust in pounds.
The Ford C6 sun gear has pitch diameter of roughly 1.8 inches.
>From that you can figure the tangential force given the torque.
The helix angle from eyeball is about either 30 degrees or 60
degrees depending. Probably around 30 degrees.
I think Tracy knows what angle it is exactly.
Paul Lamar
22 degrees. Why do you take me through the calculations to get the tangential force.
Let's say we're trying to transfer 200 HP at 6500 RPM.
Finn
My trig calculator battery is dead. Did you get a digital camera Finn?
If so take some pictures of the shaft. It is hard for people to follow
what you are trying to do. Or make a sketch with dimensions and send
it to me. I will then make a drawing. I think we can come up with some
way of putting an effective thrust bearing on the machined side of the
bell housing. Did you look for a new input shaft?
Paul Lamar
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