On Fri, 11 Feb 2011 20:35:56 -0500, "Phil Kangas"
wrote:


wrote in message
.. .
On Fri, 11 Feb 2011 19:32:48 -0500, "Phil
Kangas"
wrote:


"Steve W." wrote in message
Karl Townsend wrote:
The new ring gear for my tractor flywheel
should arrive today...

I've never done this. Pretty sure you just
heat
it and drop on. OK,
how hot? I know there's only one shot, f%^k
up,
and go buy another
ring gear. I'm planning to go round and round
with the rose bud and
need a guide line like hot enough to smoke
oil,
etc. I got no way to
measure the temp. Surely, it don't need to go
to red hot.

Karl

Toss flywheel in freezer, make sure it is DRY
when you are ready to drop
on the ring gear though.

Toss the ring gear in an oven at 400 degrees
for
20 minutes.
Pull the ring gear out, drop it onto the
flywheel.

Let them stabilize at room temperature and
you're done.

--
Steve W.

Is it really necessary to freeze the flywheel?
Has
anyone ever
measured the reduction in diameter doing it this
way? Seems
to me to be a waste of time, the ring gear will
expand far more
than the wheel shrinks.......IMO......, eih?
phil
k.


As stated previously it is the temperature
differential that matters,
and to get adequate differential by heating
alone the heated part may
be over-heated. By srinking the second part you
gain significant
differential advantage without the danger of
damaging the outer part
from overheat. If they are made of the same
material each will change
size by virtually the same amount per degree of
temperature change, in
opposite directions.

Yah, but, the flywheel is cast iron and the ring
is steel. Cast won't
move as much as steel. We need some actual
measurements!!


Expansion rates per degree F i n microinches for various irons and
steels are as follows:

Grey Cast Iron 5.8
3% carbon cast steel 7.0
Ductile Iron 5.9 to 6.2
Maleable Iron 7.5
Nodular Iron 6.5
Pure Iron 6.8
Wrought Carbon Steel 7.8

Has the flywheel material been definitely identified? Some are cast
steel, some are nodular iron, and very very few are grey cast iron
(and then some are aluminum).

Assuming it is cast steel or nodular iron and thering gear is carbon
steel, there is a 10 to 20 percent difference in the rate of
expansion, so you get 10-10% more movement per degree out of the ring
gear than the flywheel.
In this case, that is hardly significant.