Check Track Sag - Hitachi ZAXIS 120-6 class Operator's Manual

Check Track Sag

--- every 50 hours
If the amount of sag is inappropriate, the tracks may flap
around or come off. This in turn may damage the track itself
and other parts.
As such issues will have an effect on the lifetime of the
machine, be sure to adjust the sag of the tracks to a suitable
amount.
To measure or adjust the tracks, park the machine on firm and
level ground.
Measurement Procedure with Track Raised
1. Raise a track as illustrated at right to measure its sag, and
support it securely with blocks or the like.
d
CAUTION: Take care that no hands, feet, or other
body parts are put beneath the track.
2. Remove any deposits on mating parts of the tracks and
undercarriage (top/bottom rollers, idler, sprockets).
IMPORTANT: Accurate measurements cannot be taken if
there are deposits on mating parts of the tracks and
undercarriage (top/bottom rollers, idler, sprockets).
3. Rotate the track in reverse to eliminate track looseness
on the upper side of the side frame.
4. As illustrated at right, take measurements midway (A)
between the reduction gear and the idler
(bottom of side frame to top of shoe).
Model
ZX120-6 class
ZX160-6 class
ZX200-6, 240-6 class
ZX300-6, ZX330-6 class
If track sag is not within specifications, loosen or tighten the
track.
Adjust Track Sag
1. Adjust the tracks one at a time, with the track in the
air. When doing so, be sure to place blocks under the
machine frame to support the machine.
2. After adjusting the sag on both track, rotate the tracks
backward and forward to equalize the sag on both sides.
3. Recheck the track sag one more time. Readjust as
necessary.
MAINTENANCE
Appropriate sag A (mm)
250 to 280
285 to 320
300 to 335
340 to 380
7-119
M104-07-067
MDFY-07-149
MDFY-07-149
A
MDFY-07-150