Page 159 - Moving the Earth_ The Workbook of Excavation

ROCK, SOIL, AND MUD

ROCK, SOIL, AND MUD 3.53

If the track is off the bull wheel, truck rollers, and idler but is still on the support rollers, the whole
track and wheel assembly should be raised off the ground, and the bull wheel rotated backward.
The track can be engaged with this at the top by use of a crowbar, and will be pulled into engagement
with the rest of the bull wheel, then the truck rollers and finally the idler. Caution should be used
to prevent the track from coming off completely in one place while being meshed in another.
If none of these stratagems work, or if the track is entirely off the wheels, the track adjustment
should be loosened and the track “broken” by removing a lock and driving out one of the hinge
pins, using the bull wheel as a brace. On most makes, there is only one master pin which can be
used. The side of the machine should be raised off the ground, the track placed correctly under the
wheels, the machine lowered, and the track wrapped around the bull wheel and idler. The ends
should be pulled or forced together at the bull wheel or between it and the top of the idler, by chain
tighteners, block and fall, winch, jacks, elbow grease, or any other means available, and the pin
inserted and locked. This is a difficult and laborious job, even on a small machine, except for expe-
rienced personnel; and on a large one it may require the use of other machinery to handle the track.
It is sometimes easier to replace a track, after opening it, by walking the machine off it onto a
plank or beam, aligning the track behind it, and walking it back, than to shift the track around
under the machine.
This type of work has been rendered much more difficult by changes in track design and fabrica-
tion. A single master pin may be difficult to identify and to get at. When found, it may be so tight
that it cannot be driven out until the links are heated with a torch, and the links may be bent by
the heavy hammering, during either removal or replacement.
It is common practice among service workers to cut a pair of links with a torch; then take the
whole track to a press to be reassembled. A minor incident may be turned into an expensive and
time-consuming project in this way.
Split master links make this drastic step unnecessary. They permit opening a track by removing
a shoe, then taking out four bolts. Opening the track and closing it are greatly simplified.