b.
Lift up on tightener sprocket to tighten, or
3-33. Dipper Trip Adjustment
lower to loosen boom crowd chain, then tighten
adjusting nuts.
a.
If the brake drum (fig. 3-28) does not tend to
rotate when dipper trip lever (fig. 2-23) is operated, the
c.
Proper adjustment allows from three to four
brake shoes (fig. 3-28) are probably worn enough to
inches of sag in chain between shipper shaft sprocket
require adjustment.
and chain tightener sprocket.
b.
Turn the bell crank (underneath revolving
d.
Adjust revolving frame crowd chain in a
frame) until the brake shoe just barely drags against
similar manner.
brake drum; turn bell crank back until brake shoe is just
clear of the drum, then loosen locknuts on rod and
3-32. Anti-sway (Boom Foot) Spring Adjustment
adjust length of rod until top and bottom levers are both
from 15 to 20 degrees below a horizontal position.
a.
Tension on anti-sway springs allows boom
c.
Loosen lever locknut and adjust setscrew so
some freedom of movement, yet prevents excessive
that travel of rod is stopped before lever is bottomed in
swaying. At installation, tighten adjusting nut (fig. 3-27)
upper clevis and bends rod.
to compress spring until it is 14-5/8 inches in length.
d.
When brake shoe adjustment is correct,
CAUTION
tighten two locknuts on rod, and locknut on setscrew, to
Never tighten spring enough to
hold the adjustment.
remove clearance between coils. If
spring coils are bottomed, all strain
3-34. Trip Cable Adjustment
will be transferred to boom foot lugs
and damage to the revolving frame
a.
Assure that trip cable is fastened to equalizer
will result.
bracket (fig. 3-29) with a cable clamp; loosen clamp at
bell crank; take up all slack, then refasten cable clamp
b.
Operator will check shovel anti-sway springs
at bell crank.
frequently. When length of spring is correct, but
b.
Assure that boom trip cable is reeved
excessive sway occurs because of weakened springs;
correctly; from take-up drum mounted on shipper shaft;
replace old springs with new, and adjust as directed in a
through equalizer sheave on equalizer bracket, then
above.
over idler sheave to dipper trip lever mounted on dipper
sticks near dipper.
c.
If there is any slack in boom trip cable;
loosen cable clamp at dipper trip lever; take up slack
until dipper trip lever is just downward from
perpendicular to the dipper sticks, then secure cable
clamp.
d.
Adjust length of trip chain as required.
3-35. Hook Roller Adjustment
a.
Lower boom to near the horizontal position.
This will put weight on rear hook rollers while both front
hook rollers are being adjusted.
b.
Remove screws, lockwashers and keeper
plate (fig. 3-30), then rotate eccentric shafts until both
rollers are snug against bottom of roller path. A
maximum of 1/16 inch clearance is allowed between
hook rollers and roller path. When adjustment is
correct, install keeper plate and secure with lockwashers
and screws.
c.
Build up cribbing equal to revolving frame
height under boom, and lower boom to reset on cribbing.
This will equalize weight of revolving rollers in same
manner as front hook rollers above.
Figure 3-28. Dipper trip adjustment points.
3-37
