New England used to be famous for frugal farmers who never let anything from
heavy equipment to light trucks go to waste. As the only guy in the neighborhood
with a fully equipped machine shop, welding rigs and the knowledge to use
them, Mike often finds himself helping neighbors out of a jam - another New
England tradition. On Sunday, the jam was a cracked U-Joint ear from the
front end of a Jeep, the outboard part of a front wheel axle. The U-joints
were shot, and when a neighbor tried to press them out in order to replace
them, he cracked an ear on the steel casting. It's rumored that he hadn't
removed the snap ring, but that's another story.
It turns out that trying to press the bearing caps out of the ears on an
old shaft is always a risk, as they are almost certainly rusted in place.
The professional way to do it, if you have the equipment, is to cut the U-joints
out with a torch. There's no difference in principal between the U-joints
on this 1997 Jeep and the drive shaft U-joints for any tractor, backhoe or
excavator. Whether it's a PTO shaft or a drive shaft joint, it's the most
rugged way heavy equipment manufacturers have come up with to transfer power
through changing angles. To the left, Mike torches out the old U-joint, which
barely flames at all. When the joint has failed over a long period of time,
there's a decent chance there's not enough grease left in catch fire and
spit like a flame-thrower, but it's not something you want to try if you
don't know what you're doing.
To the right, the bearing cap comes out of the ear of the separated axle
stub after a couple of hammer whacks with a drift pin. It's important to
support the ear itself on something solid, in this case the edge of steel
bench top, as opposed to having the whole piece gripped in a vise but the
ear hanging out in the air. So much for the right way to do it. Below Mike
is grinding out a "V" cut in the cracked axle U-joint housing. It's necessary
to increase the size of the break both to get room for the wire MIG to deposit
new steel, and to prepare the surface for welding. When working with old
castings, it's never a sure thing that a weld will penetrate properly and
hold because the casting alloy might not be a normal steel, but a professional
welding service can at least effect temporary repairs on most equipment.
A professional MIG welding outfit doesn't suffer from "hot tip" or other
home-owner welder issues that distract from the actual welding process. It
only takes Mike a few seconds to get his first layer of weld in place and
determine that it's taking in the video below. Operating out of Hardwick
Massachusetts, EERS handles welding repair jobs of
all sizes and descriptions. From rebuilding excavator
buckets to repairing industrial grinders and
farm equipment, Mike has encountered it all. For quotes, contact Mike Dougan
at 413-477-0225. By combining machine shop services with in-house and on
the road welding and rigging, Mike can handle most heavy equipment and conveyor
system problems without having to bring in third party contractors.
Below the video shows the first weld being ground down for inspection. If
the weld doesn't take, there's no more point in piling more weld on top than
there is in adding to a cold solder joint. After the weld in reground and
inspected, it can be built up a little more to provide added strength and
conformity with the original geometry. When repairing the axle ear for U-joint
bearing caps, it's better to leave the ear just a little loose than to make
it so tight that the new bearing cap cracks the ear again on installation.
One trick is to go around the inside of the ear with a punch and dimple the
bearing surface, which effectively reduces the diameter of the opening at
those spots as the indent raises lip just like a stone cast in a lake raises
a wave. It doesn't hurt to load up on Loctite bearing sealant to help keep
a loose bearing cap from moving, but with the snap ring in place on the U-joint,
it's not going anywhere unless the weld fails.
