JLG | Compact Crawler Booms X26JP - X770AJ - Rubber Track Maintenance

When gravel or mud are blocked between the toothed wheel and the track links, remove it before loosening.

• Remove the screws and take of adjustment access lid 3.

• To loosen the track, slowly unscrew valve 1 in an anti-clockwise direction for no more than one turn. One turn of valve 1 is sufficient to loosen the track.

• If the grease does not start to drain, turn the track slowly.

• When correct track tension has been obtained, turn valve (1) in a clockwise direction and tighten it. Clean all traces of grease.

• To tighten the track, connect a grease gun to greaser (2) and add grease until belt tension is within the specified values.

DANGER: IT IS NOT NORMAL IF THE TRACK REMAINS TAUGHT AFTER HAVING TURNED VALVE (1) IN AN ANTI-CLOCKWISE DIRECTION OR IF THE TRACK IS STILL LOOSE AFTER HAVING PUT GREASE INTO GREASER (2). NEVER TRY TO REMOVE THE TRACKS OR DISASSEMBLE THE TRACK-TENSIONER CYLINDER BECAUSE THE GREASE PRESSURE INSIDE THE TRACK IS VERY DANGEROUS.

The structure of the rubber track is illustrated in Figure 3-3. The steel ropes and the metal core are sunk into the rubber. The carved profiles are used to give stability when moving over loose land. They are situated in the lower part resting on the ground, while the wheel guides situated inside the track, prevent the track from escaping from the guide rollers.

1. Breakage of the steel ropes. Excessive tension causes the steel ropes to break in the following conditions:

• when stones or foreign bodies accumulate between the track and the under-carriage frame

• when the track escapes from its guide

• in the case of strong friction such as rapid direction changes.

2. Wear and breakage of the metal cores. As for breakage of the steel ropes, stated above, excessive tension may cause the metal cores to bend or break, as may the following causes:

• incorrect contact between toothed wheel and track

• breakage of internal rollers

• functioning on sandy land.

3. Separation of the metal cores

• The metal core acts as a type of adhesive of the rubber between the core itself and the steel ropes. Separation may be caused by excessive tension as breakage of the ropes for the following reasons

• The metal cores have been wound by the worn toothed wheel as indicated in the figure. When this wear and abrasion is detected, the toothed wheel must be replaced as soon as possible

• If it breaks, as stated in item 2, "Wear and breakage of the metal cores", the track must be replaced because this damage leads to a complete loss of functions.

4. Abrasion and fatigue cracks

• The cracks at the base of the carved profile occur due to bending fatigue of the rubber caused by the toothed wheel and the tracktensioning wheel

• The cracks and bends on the edge of the rubber are due to manoeuvres with the track in presence of cement kerbs and edges.

• The cracks and abrasions in the rubber on the tracks of the roller guide originate from fatigue from the compression of the rubber by the weight of the wheel, together with functioning on sandy land, or repeated and abrupt changes of direction.

• Abrasion of the carved profiles may occur especially if slewing on concrete surfaces or on gravel or hard surfaces are carried out.

• The damage indicated in paragraphs a, b, and c above, must not be considered fatal for the track and, even if in presence of gradual and progressive damage, they allow the track to continue working. The development of the damage indicated in point 3 leads to the exposure of the metal cores and if they are exposed for more than half of the track circumference, it means that it is time to replace them. It can however still be used.

5. 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 rubber properties point of view, this is inevitable although it does depend on service conditions. Cracks on the internal surface of the circumference and on the edge of the rubber originate from contact of the belt with the structure of the undercarriage or with sharp concrete edges. The increase in cracks is relatively small. Even if it does not appear to be in good condition the track can be used in heavy duty conditions.

DANGER: THE GREASE CONTAINED IN THE HYDRAULIC TRACK IS PRESSURISED. FOR THIS REASON, DO NOT LOOSEN THE GREASING VALVE (1) BY MORE THAN 1 TURN; IF THE VALVE IS LOOSENED TOO MUCH, IT RISKS BEING EXPELLED UNDER THE EFFECT OF THE PRESSURE OF THE GREASE, PUTTING THE SAFETY OF THE OPERATOR AT RISK. NEVER LOOSEN GREASER (2).

When gravel or mud are blocked between the toothed wheel and the track links, remove it before loosening.

DANGER: ENSURE SAFE CONDITIONS WITH THE MACHINE LIFTED TO PROCEED WITH MOUNTING THE TRACKS