Probably one of the greatest perils in owning vintage machinery
lies in the eccentricities of former owners. In some cases you can
track down the original owner to ascertain the machine’s
condition. But of the many old machines I have owned, I have never
had one unit I could connect to the original owner.
That was the case with the ‘Nimble T-6’ (see
GEM, August 2003), my 1952 International Harvester
bulldozer. In that first article, I wrote about modifying the
T-6’s controls to make it easier for me to operate. That
modification worked fine, but the unit had problems with the
tracks, which I had yet to confront. Specifically, the left track
was good, but the right track was in bad shape: The street grousers
were bent and smooth, and the bushings were worn through to the
pins.
I made several inquiries to firms that replace pins and
bushings, and the best deal was with a firm in Lancaster, Pa. The
cost of replacing the pins and bushings would be about $700 – the
big problem was getting the track the 150 miles to the repair shop.
For the past 70 years my main hobby has been antique machinery and
metal working. I have maintained a shop of sorts, equipped with a
lathe, drill press, power hacksaw, welding equipment and many
sundry tools. I have had occasion to shrink fitted bearings with
heat, and I’ve used heat to loosen tight parts.
Getting to Work
Given these problems, I decided to experiment with rotating the
bushings in place in the links – and on the tractor. To do this I
made a substantial clamp from some heavy pipe and plate with a boss
that would engage the void in the bushing caused by wear. The clamp
was held together by 3/8-inch high-strength bolts. I welded a heavy
stub of steel to accommodate a 5-foot length of 1-1/4-inch pipe to
the clamp.
Somewhere along the line I acquired two propane burners, and I
clamped these in position so the flame would impinge the link. I
arranged a cable from the pipe attached to the clamp to an overhead
pulley, and then to my 14 HP hydrostatic garden tractor. I fired
the propane torches, waited two minutes, got on the tractor and
after a little slipping the bushing began to turn. The final result
was that the bushings rotated about 130 degrees. Unbolting the hot
clamp and repeating the process was time-consuming, but the end
result was worth it.
The total track length was shortened by 3 inches. We have used
the machine with both the loader bucket and the bulldozer blade,
and have had no slipping of the chain over the sprocket. Surely
someone must have used this process before? There are no doubt many
crawlers (some not too old) with worn-through bushings. If a person
had to have a machine shop fabricate a clamp, it would still be
less expensive and a lot less bothersome than having the pins and
bushings renewed.
There is a possibility of heat having a negative effect on the
links. According to an official International Harvester Co.
publication, the links are drop-forged and heat-treated. This means
the links are heated to 2,000 degrees F in several steps for
drop-forging, and for the heat-treating the metal is heated to
1,350 degrees F and the cooling timed. I borrowed a
high-temperature heat-recording device, and the average heat of the
metal in the link was 450 degrees F when the bushing started to
turn. This is well below the temperature required to change the
properties of the steel.
While my experience seems like a happy ending, the fact still
remains that at 87 it is a bit risky for me to be going through the
gymnastics of getting on and off the machine.
Contact engine enthusiast Dick Holcombe at: P.O. Box 247,
Dushore, PA 18614; e-mail: dicke@chilitech.net
