OC46 drive sprocket studs

mikegt4 · February 15, 2017, 02:32:33 AM

My 1957 OC46 came to me with several missing studs and a few more with the threads stripped out in the hub/gear assembly on one side. For a few years I have been tightening the remaining 5 studs/nuts about every 200 yds. of travel which, since I don't use the machine for much more than occasional lifting, hasn't been much of a problem. This year I need to use the machine for a gravel driveway re-construction and extension so re-tightening the nuts often (or at all) isn't going to work anymore.

My question is can these stripped threads in the hub be successfully repaired with a TIME-SERT or similar insert? Also I have 2 hub/gear assemblies out of an OC3 in my spares pile, will they swap into the OC46 in the event that I can not repair what I have?

I have a mill and lathe so accurate machining is not a problem although I would rather do it in place.

Mike

Robert Barbour · February 15, 2017, 10:01:51 PM

You could try and repair the threads in the hub, but I would change it out to one from the OC 3. Now there were 3 different gear set ups for the OC3 and 4. There ratio's are all very close so if the gear from the OC3 is different than the OC 4 just use the OC 3 pinion and you will be ok. It is important to keep those sprocket nuts tight!

oliverchris · February 17, 2017, 09:44:16 PM

Helicoils etc. will work fine. I've done quite a few — and I've heard it said, that the repaired studs have greater strength because of the increased surface area. I'm not sure if that's a myth.

http://www.olivercrawlers.com/using-heli-coils-on-final-drive-gears

Robert Barbour · February 18, 2017, 02:45:28 AM

Before you consider fixing stripped threads, you need to inspect the hub. Just inside the stud circle there is a lip that holds the sleeve for the outer bearing seal. This lip is often broken off when the sprocket gets loose. Since you only have 5 of 10 studs left I would be very surprised if that lip is still there. With out the lip there is nothing to hold that seal in place so the hub would need to be changes. You can remove the ring gear from the hub by pressing them off after grinding off the rivet heads. To re-install heat the ring gear and cool the hub in the freezer. rivets can be made from 10 or 12 inch spikes.

oliverchris · February 21, 2017, 02:48:21 AM

This is the lip Robert is talking about, with the seal retainer still inserted. Yes, it's often cracked-off entirely or chipped badly on bull gears that have taken some abuse.

oliverchris · February 21, 2017, 03:16:13 AM

I've designed an insert that allows for the bearing and the seal retainer to be pressed into the hub, all in one piece of steel — much stronger. In these photos, the seal is inserted at the bottom (#1) and the back (#2).

Robert Barbour · February 21, 2017, 04:12:44 AM

That is a good idea Chris. So you can take a hub with a broken seal lip and bore it out to the depth of the bearing to take your adapter. That should save some old hubs and be a more economical repair. I will keep in mind that you have those.

oliverchris · February 21, 2017, 04:25:47 AM

Thanks Robert. Yes, that's the idea.

I used to machine just the lip insert to save the hubs, and then I thought to combine the thin-walled seal retainer with it. I wonder if it's the seal retainer shifting under a shock load delivered via worn bearings that break those lips? It'd be interesting to know if more of them break on clutch steering units that delivery larger loads to a single final drive.

I made ten inserts. If I can get to tell more people about them, I'll make more. I guess, my eBay is an option.

Have a good one...Chris

Robert Barbour · February 21, 2017, 08:10:47 PM

I think it is the sprocket that breaks the lips off when the stud nuts get loose. Once that happens the dirt gets past the seal and into the bearings and gears. It is important to check those sprocket nuts regularly and keep them tight.

mikegt4 · February 21, 2017, 11:20:31 PM

Thanks everyone for the advice.
I got most of it apart, actually everything came apart very easily. I haven't pulled the hub out yet but I have taken the front idler assembly apart to address some issues there. The idler has always been a bit out of line and I did replace the actual wheel a few years ago as the machine came to me with a section of the flange missing and a welded together axle shaft. Someone probably rammed the idler into an immovable object more than once as the rods through the springs are bent and one is smaller in diameter than the other (OC3?). Also I will take this opportunity to rebuild or replace the rollers.

As far as the sprocket, it's a mess. Fortunately I have a good spare. After a good cleaning it's easy to see why it would never stay tight. The holes for the studs have been welded to eliminate the cone washers and then ground out with a die grinder so that the sprocket would fit over the studs. Calling it a "hack job" is giving it too much credit. Work has stopped for now until the rain goes away.