Re: Twin gear box

bill Tabor

I don't no the previous history for sure. When I bought the lathe I had gone through and cleaned inside and out. Over time e and f would act as if I was winding band up.In theses speeds start out fine run for awhile start to slow down and bind, by reversing would like unwind the could go back in thread in forward speeds again.  I did not Mike the bearing or the shafts they didn't feel worn but did replace both rooler bearings in left and right tumblers.

From: <> on behalf of George Meinschein <bustedguns@...>
Sent: Saturday, June 6, 2020 7:14:24 PM
To: <>
Subject: Re: [SouthBendLathe] Twin gear box
I would say NOOOO, do not pin the f to d.  I'm pretty sure that would lock the gear train up.  Any chance the left tumbler is bent or worn enough that the tumbler idler is dropping out of mesh when in the e or f range?  Did the gearbox work fine previously and this problem just appeared one day?

George H. Meinschein, P.E.

Meinschein Engineering Consultants, LLC
150 Brittany Drive
Freehold, NJ 07728-1500

Email: george.meinschein@...
Direct Dial: 732-409-0778
Cell: 732-580-1736
Fax: 732-358-0369


On Fri, Jun 5, 2020, 12:29 PM <saddlesore07@...> wrote:
Yes the lead screw stops turning with the split nut in open position. I have notice with a flash light if I put the second tumbler in any screw pitch thread and leave the first tumbler or the speed a-g tumbler out all 3 of my drive gears turn. When as I put the first lever into e or f speeds only the first 2 main drive gears turn the 3 stops as I dis engage first lever all 3 drive gears turn, Now when I say 3  drive gears the gears are pined in pairs so you have 3 pairs on the tree shaft and 3 on the drive shaft.
Only the first pair are keyed the other pairs free wheel. According to SB manual f and g drive gears are pined as a pair been thinking of pinning them to d and f gears though the manual don't show doing this. Sorry for not getting back to group but had a death in the family.

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