# SB 9 Back Gear will not stay engaged



## RVbeemer (Jun 9, 2022)

I finally got the lathe up and running but, when I put the back gear in it runs for a few seconds and kicks out. Okay so I go to the pdf files and find the back gear maintenance page and it tells how to adjust the back gear. My problem is, I don't have the "C" bolt. There is not a hole or bolt , nothing. See pictures. Has anyone else run into this?


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## mattthemuppet2 (Jun 9, 2022)

is there no bolt on the underside of the other end of the backgear? If not, you'll need to take the backgear out and tap that hole. Put a piece of solder at the bottom and then tighten the screw to provide some drag. Takes a bit of fiddling to get it just right, but that should do it.


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## Jim F (Jun 9, 2022)

Wrong parts list.

You need to look at a 9" Jr. parts and maint. book


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## RVbeemer (Jun 9, 2022)

mattthemuppet2 said:


> is there no bolt on the underside of the other end of the backgear? If not, you'll need to take the backgear out and tap that hole. Put a piece of solder at the bottom and then tighten the screw to provide some drag. Takes a bit of fiddling to get it just right, but that should do it.


There is a set screw with a locking nut on the other end but that is for adjusting the gear mesh.


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## RVbeemer (Jun 9, 2022)

Jim F said:


> Wrong parts list.
> 
> You need to look at a 9" Jr. parts and maint. book


Jim, I don't seem to find a file for this. Any guidance would be appreciated.


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## Jim F (Jun 9, 2022)

RVbeemer said:


> Jim, I don't seem to find a file for this. Any guidance would be appreciated.


All I could find was a parts price list.



			South Bend Lathe Works - Publication Reprints - Price List of Repair Parts for South Bend Lathes | VintageMachinery.org
		


Shows your headstock.


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## RVbeemer (Jun 9, 2022)

That's what I found. No help. Why would South Bend put the adjustment screws on some models and not others? It looks as if someone pieced together a lathe from various models. I was told it was a "C " model that was converted to a "A" model but don't know anything for sure. Everything works correctly but the back gear kicking out. I know what the answer is, drill and tap a hole in the headstock for a "screw". I was hoping there was another alternative to adjusting the back gear to stay engaged.


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## francist (Jun 10, 2022)

Nice little lathe


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## RandyWilson (Jun 10, 2022)

The manual you have showing the adjuster is for the post war UMD family.  Yours is of the older line shaft driven series of machines.


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## DavidR8 (Jun 10, 2022)

@RVbeemer What's the serial number on your lathe? 
(It's stamped into the tailstock end of the ways)


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## RVbeemer (Jun 10, 2022)

DavidR8 said:


> @RVbeemer What's the serial number on your lathe?
> (It's stamped into the tailstock end of the ways)


60419


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## DavidR8 (Jun 10, 2022)

RVbeemer said:


> 60419


According to the Steve Wells South Bend Serial number database the bed is from 1935.


But the red gear ratio plaque on the gearbox indicates the gearbox is definitely from a later model.
This parts diagram from 1935 shows the back gear adjusting screws as part #246 on pg. 3 of the pdf 


			http://www.wswells.com/data/parts/1935-pl-19B.pdf
		

It looks like your machine was painted, is it possible that the holes were filled and painted?


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## RVbeemer (Jun 10, 2022)

DavidR8 said:


> According to the Steve Wells South Bend Serial number database the bed is from 1935.
> View attachment 409703
> 
> But the red gear ratio plaque on the gearbox indicates the gearbox is definitely from a later model.
> ...


I will go look at it again but i looks as though the casting is unmolested. Strange! It' as if they forgot to drill and tap the hole at the factory but surely it was run through a test to make sure the back gears engaged. If not then there is no way the back gear could ever have been used. I'll go look it over again. Thanks


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## Jim F (Jun 10, 2022)

Those early lathes did not have the same set-up as the newer version.
Looking at that parts list does not show the screw and shoe you are looking for.

Someone added a later QCGB to an older workshop model, or upgraded the old single tumbler to a double tumbler.

You DO NOT have an A model or a "converted C model.You have a "workshop" Q model with a newer gearbox.


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## RVbeemer (Jun 10, 2022)

Okay, I went out and looked the back gear over and I found something very interesting. There is a hole approximately 1/4" just below the back gear lever. It looked as though it was threaded but I blew it out with air and there is a spring in there. I tried to push it in with a small screw driver to see if it was threaded. Couldn't tell. But the lever covers just enough of the hole that the spring won't come out. I will have to remove the lever to remove the spring. The hole is 5/8" deep. I'm pretty sure it's not threaded as the lever covers too much of the hole for something to be threaded in it. See pictures. Perhaps something fits in the gap between the lever and the headstock?


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## DavidR8 (Jun 10, 2022)

Isn't this the adjuster bolt?


	

		
			
		

		
	
(My 10K back gear adjuster is exactly where this is on your lathe...)


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## RVbeemer (Jun 10, 2022)

DavidR8 said:


> Isn't this the adjuster bolt?
> View attachment 409724
> 
> 
> ...


David,
This screw adjusts the gear mesh but does not lock it in. The lock in screw puts tension on the eccentrics to hold it in place.


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## DavidR8 (Jun 10, 2022)

All I can say is that my 10K wouldn't stay in back gear and that's the bolt that I adjusted...


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## Manual Mac (Jun 10, 2022)

Will this help? It’s parts list for horizontal & underdrive 9” models fron June 15 1957.
The toolmaker or workshop models. Not the Junior (or heavy 9) which was discontinued in late 30’s or in the 40’s.
rvbeemer your lathe is not a junior or heavy 9.
it is an early workshop or toolmaker From the ’30’s. It has top spindle oilers.
also, to convert an early C like yours (there was not an A, B, or C model in the early ones) you would need a frame as well as the gearbox, as the frame did not have the relieved frame that the later A B or C had.


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## RVbeemer (Jun 10, 2022)

DavidR8 said:


> All I can say is that my 10K wouldn't stay in back gear and that's the bolt that I adjusted...


Mmmm. I'll go play with mine and see what happens. Do you remember if you went tighter or looser?


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## DavidR8 (Jun 10, 2022)

RVbeemer said:


> Mmmm. I'll go play with mine and see what happens. Do you remember if you went tighter or looser?


If I recall correctly I went looser so that there was less engagement and the lever could pass over center.


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## SLK001 (Jun 10, 2022)

That looks like an early Workshop lathe.


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## DavidR8 (Jun 10, 2022)

These are the only bolts I adjusted.
If I recall correctly, the slotted adjuster is for the engagement and the regular hex head locks the eccentric in place.
If you only have the one maybe it does double duty?


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## RVbeemer (Jun 10, 2022)

Manual Mac said:


> Will this help? It’s parts list for horizontal & underdrive 9” models fron June 15 1957.
> The toolmaker or workshop models. Not the Junior (or heavy 9) which was discontinued in late 30’s or in the 40’s.
> rvbeemer your lathe is not a junior or heavy 9.
> it is an early workshop or toolmaker From the ’30’s. It has top spindle oilers.
> also, to convert an early C like yours (there was not an A, B, or C model in the early ones) you would need a frame as well as the gearbox, as the frame did not have the relieved frame that the later A B or C had.


Yeah, that looks like mine but there is no hole for #'s 19, 20, 21.


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## RVbeemer (Jun 10, 2022)

DavidR8 said:


> These are the only bolts I adjusted.
> If I recall correctly, the slotted adjuster is for the engagement and the regular hex head locks the eccentric in place.
> If you only have the one maybe it does double duty?


David, I see you have two bolts, one on each end. The restoration manual says "The slotted screw is for the gear mesh adjustment and the square head bolt is for the eccentric adjustment." I don't have the square head bolt or hole. 1935 model


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## DavidR8 (Jun 10, 2022)

RVbeemer said:


> David, I see you have two bolts, one on each end. The restoration manual says "The slotted screw is for the gear mesh adjustment and the square head bolt is for the eccentric adjustment." I don't have the square head bolt or hole. 1935 model


Maybe the one bolt on yours does both functions?


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## RVbeemer (Jun 10, 2022)

I know the  nut is just a lock nut and when I screw the slotted screw in it pushes the gears apart and turning it counterclockwise, it lets them close up. Not saying you are wrong, just can't see where that would put any tension on the eccentric. I think I will go out and back it off and see if the lever pulls further in.


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## Jim F (Jun 10, 2022)

The workshop models did not have the parts he is looking for.......


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## RVbeemer (Jun 10, 2022)

Thanks for everyone trying to help! I was hoping someone with a lathe like mine could chime in and show what they have.
I did try to adjust the gear mesh screw but the best I could get was about 20 seconds before it would kick out. I still wonder about that hole with a spring in it. There has to be a reason for it.


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## tq60 (Jun 11, 2022)

A lot of these use "over-center" locking.

The handle rotates an eccentric that causes the shaft to get closer and farther away.

As you rotate it and see that it gets to the closest point then go just past that it opens up again.

There should be a screw someplace that is what adjusts where it stops rotating, usually just over-center.

Natural forces then will try to push the shaft against the screw stop.

Sent from my SM-G781V using Tapatalk


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## Manual Mac (Jun 11, 2022)

I had the same problem many years ago, can’t remember how I fixed it.
I think tq40 is correct here.
the only time I use back gear is in slowest position while threading.
I seem to remember it wouldn’t jump out while under a load (threading), but it would if not under load.
i think it was a simple adjustment.


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## RVbeemer (Jun 11, 2022)

tq60 & mac,
That might be the answer. I was out there playing with it and I backed the screw out and it did go all the way over and through the gears. that screw and lock nut is under the eccentric shaft. From looking at the 9ABC restoration book, it says that is for gear mesh adjustment. But since I don't have a 9A, B or C that may be what that screw is for. I will go back out there after it cools off and play with it some more. Many thanks!


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## RVbeemer (Jun 13, 2022)

Greetings everyone. Well I have adjusted the lever as far as I can without going all the way over, and it still eases out. It is a little slower but alas, does not stay put. I can hold it with very little pressure. I think I can lock it in if I remove the lever and mill a radiused groove in the side of the lever base enough to insert a pin in that mysterious hole under the lever ( see post 15). If I only had a mill! I can't help but think that hole has a purpose. Sure would like to see a drawing of a workshop model headstock but haven't found one. Thanks to all who have replied.


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## lordbeezer (Jun 13, 2022)

Hope this helps.


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## Manual Mac (Jun 13, 2022)

Beemer, in post #15, the spring in that hole should have a round detent ball or plunger of some sort between the back gear lever & the spring.
My early (1938 #84029) top oiler model has this, When moving the backgear lever I can see the detent/plunger move.
i cannot find the detent or spring in any of my parts list pages.
i also don’t know how your 1935 frame can possibly work with a later QCGB, as the frame was relieved in the later A B or C year models for clearance.
this is getting curiouser & curiouser.
EDIT: lordbeezer, I have the same diagram. It doesn’t show the detent or spring.


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## mattthemuppet2 (Jun 13, 2022)

lordbeezer said:


> Hope this helps.


That's not for the top oiler clamp on bearing shell head stock he has unfortunately. I can't offer any help as my heavy 9 has a completely different way of adjusting the back gears. Sounds like that detent pin is a possible option. Is there a matching divot in the back gear? My old Atlas 618 has a similar mechanism for keeping the back gear engaged


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## lordbeezer (Jun 13, 2022)

37 or 37 workshop 9”. Adjustment by screw bolt.


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## Manual Mac (Jun 13, 2022)

Lordbeezer, my #84029 has the same adjuster screw & locknut as your photos.
matthewmuppet, I think the lathe in question is the solid headstock non-removable spindle bearing & cap model. It’s The super finished type, like mine.
rvbeemer, i think the detent you are missing (between the backgear lever & the spring) just keeps tension on backgear fore and aft movement. Maybe just enough tension to keep it from popping out of gear. My lever does not appear to have detent notches in it, so I guess it’s tension only, just restricting loose movement. You can make a detent.
 And remember, I’m by no means an expert. I’ve had mine almost 40 yrs, I know most things about it, but still no expert.
It appears your detent may have shot out under spring pressure when removing the backgear. Kind of like parts flying out of a pistol  (never to be found) during dissasembly.
rvbeemer, your SB9 looks really good in black.
that’s all I got.
and I could be wrong about any of this.


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## lordbeezer (Jun 13, 2022)

Op’s headstock is same as mine in picture. Remove screw bolt. Pry or tap back gear handle and shaft out some and install detent and spring. Should be good to go


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## RVbeemer (Jun 14, 2022)

Manual Mac said:


> Beemer, in post #15, the spring in that hole should have a round detent ball or plunger of some sort between the back gear lever & the spring.
> My early (1938 #84029) top oiler model has this, When moving the backgear lever I can see the detent/plunger move.
> i cannot find the detent or spring in any of my parts list pages.
> i also don’t know how your 1935 frame can possibly work with a later QCGB, as the frame was relieved in the later A B or C year models for clearance.
> ...


Mac, at last, someone has one! I am going to remove the lever and find a ball and see if that will hold it. If not I will go back to a pin type plan. Unfortunately, who ever painted the lathe, painted the shaft so I'll have to work to get it off.
I don't know about the QCGB But it works just fine (after I reversed the tumblers).


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## RVbeemer (Jun 14, 2022)

Manual Mac said:


> Lordbeezer, my #84029 has the same adjuster screw & locknut as your photos.
> matthewmuppet, I think the lathe in question is the solid headstock non-removable spindle bearing & cap model. It’s The super finished type, like mine.
> rvbeemer, i think the detent you are missing (between the backgear lever & the spring) just keeps tension on backgear fore and aft movement. Maybe just enough tension to keep it from popping out of gear. My lever does not appear to have detent notches in it, so I guess it’s tension only, just restricting loose movement. You can make a detent.
> And remember, I’m by no means an expert. I’ve had mine almost 40 yrs, I know most things about it, but still no expert.
> ...


Mac, It may be for restricting loose movement but may be enough pressure to hold it. Doesn't take much. 
I knew there was a reason for the hole with a spring in it. You may be right about the ball shooting out but I'm guessing whoever "rebuilt" this lathe, probably lost it and went on with assembly


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## lordbeezer (Jun 14, 2022)

Mine has a plug instead of ball. Little more bearing surface. Can measure if would help.


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## RVbeemer (Jun 15, 2022)

Greetings All, 
An update on my back gear problem. I removed the lever and installed a ball, I actually had one on hand, reinstalled. No luck. The shaft has more slack than the ball will take up. So, I removed the lever once more after marking the hole location, and ground a slot across the side with a rotary file until the pin would fit. I actually found a 1/4" pin with a detent ball on hand! Those good old junk drawers! So, everything fits good, the lever will not ease off, problem solved! I am going to cut the pin shorter today. Thanks to everyone for suggestions and ideas and trying to help me.


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## DavidR8 (Jun 15, 2022)

RVbeemer said:


> Greetings All,
> An update on my back gear problem. I removed the lever and installed a ball, I actually had one on hand, reinstalled. No luck. The shaft has more slack than the ball will take up. So, I removed the lever once more after marking the hole location, and ground a slot across the side with a rotary file until the pin would fit. I actually found a 1/4" pin with a detent ball on hand! Those good old junk drawers! So, everything fits good, the lever will not ease off, problem solved! I am going to cut the pin shorter today. Thanks to everyone for suggestions and ideas and trying to help me.


Very happy you got this sorted out!


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