Welding on a rear axle hub

muddstopper · Feb 21, 2015

Now to just figure out how thick of steel to use for the mounting plate. I,\'m thinking 1/2-3/8 should be fine and is thicker than a truck wheel. Building something similar to this, https://www.google.com/search?q=knu...3drivers.com%2Fcatalog%2F320%2F361%2F;400;400 but boom wont be quite as heavy

Shield Arc · Feb 21, 2015

I'd use 1/2-inch at a minimum, but would feel safer with 3/4-inch thick plate, with at least 4 gussets.

metalmaster · Feb 21, 2015

keep in mind a truck wheel has very little leverage compared to a lever arm several feet from the pivot.

muddstopper · Feb 21, 2015

I am just planning a light weight boom. The hub is a 48000lb rear end. Half that is 24000lb. I am guessing at the leverage since I dont really know how to figure it. 1500lb at about 14ft should be around 21,000lb. Since most lifts are not made at max extension, and axle safety factor is about 5-6:1 and use speed as a factor, I should be ok. If you know something I am not considering, please point it out.

mikefromnh · Feb 21, 2015

How about something like this instead?

Slewing Ring Bearing with Outer Gear 12 14" OD with Matching Hydraulic Motor | eBay

CNC Dan · Feb 23, 2015

Shield Arc said:
I think that is your safest route! A mechanical connection is a lot safer than an unknown welded connection.

Old saying:

"A good welder knows when to use a bolt."

CNC Dan · Feb 23, 2015

metalmaster said:
keep in mind a truck wheel has very little leverage compared to a lever arm several feet from the pivot.

But they go over bumps and pot holes.

muddstopper · Feb 27, 2015

Tons of snow outside, doubt I will be working on this again this weekend. I have located some 1/4in 4x4 tube to use for the boom. Spent a lot of time trying to figure out the angles for making the boom and cyl mounts. Think I have the math figured out. Going to draw it out on the shop floor before I start cutting and welding. Still looking for a 60+ tooth double #60 sprocket, Theres a 78tooth one on ebay at a good price, but dia is over 17in. Would work great for the swing, but not sure I have the clearance to make it work. Hub flange is a a little over 13in dia. I plan on boreing the sprocket to fit over the backside of the hub and drilling it for lug patten, about 11.25in bolt circle. I figure the large lugs, if long enough, should provide enough support to hold the sprocket and the boom mount together. Not sure the lugs are long enough, I might have to bore the lug holes out to accept regular bolts.

ts01 · Feb 27, 2015

a good cast rod is cast alloy t-60. used it many time great results

BukitCase · Feb 27, 2015

You're limited by chain pitch as to how many teeth in your sprocket - since #60 chain means 6/8" spacing on the rollers, 60 teeth would result in a circumference (at the center of rollers as they sit in the sprocket teeth) of 45 inches, or diameter (plus twice the amount the teeth stick up past center of rollers) of 14.324" - add maybe an inch and a half to that, and a 60 tooth sprocket would come out to close to 16" in diameter.

Only way around it I can see is if you didn't need/want a full 360 deg. rotation - then you might be able to cut a half circle or some other portion of it, if that would buy you any clearance.

Dunno if you've seen this, but the guy has some fun stuff on his site -

Notes on Sprockets and Chains

Have you considered maybe a ring gear on your truck hub, driven directly by a slow speed hydraulic motor with a smaller gear on it? Might be harder or easier, just throwing stuff out

... Steve