On Jan 13, 7:57*pm, Bob Engelhardt wrote:
I got a rototiller at the dump. *The motor is fine, but it wouldn't
shift gears. *The "transmission" was a bitch to get apart, but I did it
and found rust, as I expected. *I'm undecided between pitching it and
rehabbing it.

Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp

My feeling is that under these conditions the transmission would last a
long time and perform normally, if noisily.

Finally, I like to rehab machines, but I don't like to waste my time.

A pic of one of the gears after HCl de-rusting and bead blasting (the
teeth are about 1/4" wide):http://home.comcast.net/~bobengelhardt/RustedGear.jpg

Waddaya think?

Bob

I've got an old Gravely tractor and several gearboxes for the rotary
plow and rototiller attachments. The gearbox has a ring and pinion
gear setup very like that in an auto rear end. About the same size as
auto ring & pinion gears. Pinion runs at PTO speed which, as I
recall, is at least 1,200 RPM.

The pinion gears are machined steel, but the ring cears are cast iron
- with no machining of the gear teeth. As long as they are kept
lubricated, they work fine. Horsepower is in the 5 - 7.6 range, but
they can handle more.

If those cast iron gears hold up, I'm guessing yours will as well. If
not, well, it's a rototiller. It's not likely to leave you stranded
in downtown Birmingham.

John Martin