SB9A Undermount Drive Belt Tensioner

[Skowinski]

Well, I'm back with another (probably dumb) question that I can't find an answer to googling or digging through the info that I have here. I'm about to put the drive assembly back in the cabinet and started looking at this - it doesn't seem right as it came to me.

The shaft that the lever rotates to put tension on or off the drive belt has a collar with an indent in it. It looks like the arm with pin hovering above the collar might be supposed to fit in this indent at some point of the rotation. But, as this thing is currently assembled the pin never contacts the collar, much less goes into the indent, and the indent itself is apparently at a random point in the rotation, not at one end (tension on) or the other (tension off) or even right in the middle.

I know South Bend wouldn't go to the trouble of making this setup if it didn't have a function. As currently assembled this does nothing at all. Any advice?

 

[Superburban]

I looked through the files I have, and none of them mention, or show the indent parts. I did not take the under drive apart on mine, but cannot see anything close in the tons of pics I took. But mine is a 16" so no surprise there.

You call it an arm with a pin, is there anything attached to the arm? If the arm/pin were to drop in the hole, how would you pull it out?

I'll keep looking when I get more time, you have me curious.

 

[Bobby Bailey]

That looks like the safety mech. to prevent the opening of the cone pulley cover. To open the door the belt tension lever has to be in the untension position. There should be a rod that goes from what you are showing up to the back of the cover.
At least that is how it works on my 10K.

 

[Skowinski]

Thanks for the comments guys. The arm/pin (24/25) seems to be held back against the frame with a spring, which holds it away from the collar with the indent. When the lever is rotated into the "on" or "off" position it will definitely stay there because of the cam (20) at the end of the rod.

Bobby - there is a "cover lock rod" part #3 or 51 - hadn't noticed that before, and there is no sign of one on this machine. So it runs up through the headstock to the cover? I guess without this mechanism a fool could open the cover while it's running and stick his hand in there....