SB 9 Back Gear will not stay engaged

[Manual Mac]

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.

 

[RVbeemer]

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!

 

[RVbeemer]

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.

 

[lordbeezer]

Hope this helps.

 

[Manual Mac]

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.

 

[mattthemuppet2]

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

 

[lordbeezer]

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

 

[Manual Mac]

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.

 

[lordbeezer]

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

 

[RVbeemer]

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.

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).