To operate a tracked excavator correctly an operator needs to “unlearn” the skills they use when operating a wheeled vehicle.
Training your excavator operator to use an excavator correctly is the easiest way to extend your undercarriage life.
An excavator is designed to travel with the idler at the front of the machine and the sprocket at the rear. Travelling in reverse is the greatest cause of pin, bushing and sprocket wear.
Reason: In reverse the track bushes rotate exactly at the point of greatest torque contact with the sprocket, wearing the bushes, pins and sprockets (in forward movement they rotate at the point of least torque resulting in minimal wear)
Reverse travel puts the track adjuster spring into tension on the idler, which tightens the chain and reduces the ability of the spring to absorb shock loads, both of which increase and accelerate wear. (Idler in front travel enables the spring to operate in compression to absorb shock loads during travel which minimises wear).
The faster the travel speed of the excavator the greater the relative load between the components (increasing wear). Over long distances friction causes heat to build up within the rollers, idlers and drives which can damage the internal seals.
Look for: Sprocket teeth that are worn to look like wave caps (swept back in one direction).
Leaking rollers and final drives.
Higher speed equals higher impact with the ground. As an excavator does not have an independent suspension this means that both tracks are stressed by an uneven surface encountered on any side.
Reason: The high impact point loads damage the track shoes.
High impact unbalanced loads accelerate wear on all moving components.
Look for: Bent / Buckled grouser shoes.
Grouser corner wear, the grouser wears back at the ends of shoe because it is sliding when making contact with the ground.
Reason: The overhead dig / dump cycle causes stress and motion (i.e. wear) at the point of sprocket / bushing contact over the sprocket (these forces should be over the idler where minimal chain rail wear then occurs).
Reason: Working along a gradient tilts the machine to one side. This increases the load / stress on the lower track, accelerating overall wear on this track (especially idlers, rollers and chain sides).
Look for: The flange on the roller is designed to stop the chain sliding off the roller. On a slope more weight is on one set of rollers and the chain slides towards the lowest roller flange. This causes accelerated wear on this flange as well as on the side of the chain link where it is forced to rub against the roller flange.
The dig-slew-dump cycle puts pivot stress (i.e. wear) on the undercarriage on the dump side of the machine.
Suggestion: Try to balance the slew direction if possible by (for example) turning the excavator around in the middle of the shift.
Excavators are useful on restricted work areas because they can make “pivot” or “counter rotation” turns. However, on sloping and hard / rocky ground, pivot turns accelerate wear.
Suggestion: Try to make sider turns or Y turns. Turn on level ground if possible.
Look for: Grouser corner wear, the grouser wears back at the ends of shoe during pivot turns on hard ground.