Figure 3-38. Hook roller adjustment points
(2)Remove two capscrews, lockwashers, and
bracket. The lip of rear hook roller keeper plate
lockplate from the adjusting block on outboard bearing
must be on outside of the eccentric shaft.
of both propel sprockets, then turn adjusting nut on
d. When adjustment is correct, raise boom to
adjusting bolt, in or out, until crawler drive shaft is
operating position.
parallel to the rear axle. When adjustment is correct,
Caution: If boom tip had been lowered to rest
install lockplates and secure with lockwashers and
on the ground because no cribbing was available,
capscrews.
be sure and get assistance from another crane or
hoisting device to lift boom tip above the horizontal
3-41. Track Adjustment
before using boom hoist to position boom. Booms
a. General.
The crane-shovel unit should be
have been known to collapse under stress applied
propelled in a forward direction for a distance equal to
by boom hoist clutch when boom tip was lower than
length of crawlers, in order that sag in track will be on
boom foot.
top. Adjust as follows.
b. Adjustment.
3-40. Propel Chain Adjustment
(1)Position a straight edge on track parallel with
a. General. To properly adjust the propel chain, the
frame, between upper roller (fig. 3-40) and high point of
crane-shovel should be propelled backward for at least
track on top of drive sprocket. Measure distance
the length of the crawler frame. This will place the slack
between straight edge and low point of track sag. This
in the chain on top. Adjust as follows.
distance should be approximately 11/2 inches. If sag is
b. Adjustment.
more than 11/2 inch, loosen locknut on adjusting bolt
(1)Back off locknuts on two eyebolts (fig. 3-39) (one
(on both sides of sprocket), then tighten adjusting nuts
on each side of sprocket) then, alternately turn adjusting
until sag is correct.
nuts, first on outside then on inside, in or out until slack
Caution: Equalize turning of adjusting nuts, so
in propel chain can be raised approximately 11/2 inches.
that idler shaft is parallel to front axle. The teeth on
Repeat on opposite side of frame for remaining propel
idler sprocket must be centered between side bars
chain. When adjustment is correct, tighten locknuts to
on crawler track. Be sure locknuts on adjusting
secure adjustment.
Note. When a new propel chain is installed, it
must be adjusted tight (no slack), to allow for
stretch.
3-44
