Excessive wear
Check the idler wheel for signs of heavy abrasion, grooving or flat spots. Worn down idlers will not support the track properly, reducing traction and stability. Idlers that are 1/2 inch or more narrower than new ones should be replaced.
Cracking or damage
Inspect the idler for any cracks in the rubber compound or damage to metal cores/spindles. Structural failure compromises the idler’s ability to support and guide the track.
Loose components
Ensure all bolts and nuts securing the idler to the idler frame are tight. Loose hardware can lead to idler misalignment and premature replacement need.
Noise
Excessive squealing, grinding or rattling noises when the excavator is moving can indicate a failing idler. Worn out idlers often cause more noise.
Visible separation
Check for any visible cracks forming between the two halves of split idlers or separation between the rubber and metal on segmented spindles. Complete separation would immobilize the track.
Difficulty moving tracks
If pushing one track control lever becomes noticeably more difficult than the other side, it likely means an idler is failing to cradle and support the track properly.
Safety issue
If the condition of an idler raises concerns over stability, traction or control, it should be replaced immediately regardless of hours of use. Safety should not be compromised.
Some factors that accelerate idler wear and replacement on Hitachi EX35 excavators include:
Excessive load
Frequently handling heavy loads at the limit of the excavator’s capacity rating will put more stress on all undercarriage components including the idlers.
Harsh operations
Activities such as constant switching between carry, travel and dig with an overloaded bucket require more work from the undercarriage and will wear out idlers faster.
Severe conditions
Operating in abrasive, wet or corrosive environments exposes the undercarriage and idlers to more damage and accelerated deterioration.
Inadequate lubrication
Lack of lubrication is probably the fastest way to damage Hitachi EX35 idlers
and other undercarriage parts. Stick to the recommended lubrication schedules.
Old idler
Replacing worn out idlers earlier will help prevent further damage to adjacent components like tracks, rollers, sprockets etc. If in doubt, it is best to replace idlers on the early side.