JLG X17J Plus Operator Manual - Manual (Page 125)

‑ incorrect contact between sprocket and track;
‑ internal breakage of rollers;
‑ operation on sandy ground.
C) Separation of the metal cores
The metal core acts as a sort of adhesive for the rubber between
the core itself and the steel wires. Separation may be caused by
excessive tension, for the following reasons:
‑ the metal cores have been wound by the worn sprocket as
shown in the figure. When this wear and abrasion is detected,
the sprocket must be replaced as soon as possible.
In case of breakage, as described in paragraphs A‑B‑C, the
track must be replaced because this damage leads to a comple‑
te loss of functionality.
D) Abrasion and fatigue cracks
1. The cracks at the base of the pattern occur due to bending fatigue of the rubber caused by
the sprocket and the idler roller.
2. The cracks and bends on the rubber edge are due to operations
with the track on cement kerbs and edges.
3. The cracks and abrasions in the rubber on the roller guides originate from the compres‑
sion to which the rubber is subjected due to the weight of the sprocket, as well as from
operation on sandy ground, or repeated and abrupt changes in direction.
4. Abrasion of the pattern may occur especially if slewing on concrete surfaces or on gravel
or hard surfaces.
The damage indicated in paragraph D points 1, 2, 3 must not be considered critical for the
track and, even if in presence of gradual and progressive damage, the track can still continue
working.
The damage indicated in point 3 leads to the exposure of the metal cores and if they become
exposed for more than half of the circumference of the track, it is time to replace them. The
track however can still be used.
E) Cracks due to external factors
Cracks on external track surfaces (those in contact with the ground) are often due to contact
with gravel, sharp stones, sharp materials, nails, glass, which cause cuts. From the point of
view of the rubber’s properties, this is inevitable although it does depend on service condi‑
tions.
Cracks on the internal surface of the circumference and on the edge of the rubber originate
from contact of the track with the structure of the undercarriage or with sharp concrete edges.
The increase in crack severity is relatively small. Even if it does not appear to be in good con‑
ditions, the track can be used for heavy‑duty applications.
X17JPR0020413
BOOM LIFT MODELS X17JPLUS
JLG
121
PARTI USURATE
W ORN PARTS
CRACK