In more ways than one, there's a lot riding on an excavator's undercarriage, so diligent maintenance is key.

"Good routine maintenance keeps the overall cost of ownership down," says Chris Giorgianni, general manager of product marketing for JCB. "It extends the life of the wearing parts of the machine, such as sprocket, idler, chain and pads. It also stops vibration in the machine and damaging movement if these wear items are looked after well."

Scott Emmans, district service manager at New Holland Construction and Kobelco Construction Machinery America, explains, "The moving components of the undercarriage are wear-items, meaning they are expected to wear over time in the process of doing their job. The bottom rollers carry the weight of the machine while it is traveling and digging. The front idler holds the track chain in proper alignment while the machine is traveling and acts as a shock absorber and chain tensioner."

He adds, "The upper rollers carry the chain in alignment and are high enough to allow debris to fall from the chain, so it is kept relatively clean. The drive sprocket engages the track chain and propels the machine by pulling the chain over the sprocket.

"These components wear out over time," he continues. "With proper maintenance and normal use, their life should be reasonably long. With poor maintenance and rough operation, their life expectancy will be less. This becomes a significant issue because these