WHEEL, IDLER

551 998 31C WHEEL, IDLER this is the big, free-spinning wheel that keeps your track chain running straight and true on the undercarriage. It’s not a drive sprocket, so it doesn’t transmit power, but it’s absolutely critical for guiding the track around the front or rear of the machine. Essentially, it helps maintain proper tension and alignment, which stops the track from getting sloppy or, worse, jumping off the rollers when you’re maneuvering on rough ground.

When these idlers start to wear out, you’ll usually pick up on a few things pretty quick. The most common sign is a distinct grinding or squealing noise coming from the undercarriage, especially when the rig is moving or turning. Sometimes you’ll notice the track chain getting a bit loose on one side, or even starting to climb the idler flange because the bearings are shot or the rim is worn thin. If it gets really bad, the track can actually derail, and nobody wants to deal with that mess out in the field. Keep an eye out for excessive play if you try to pry the track up with a bar.

Replacing an idler isn't the worst job you’ll ever do, but it’s definitely not a quick twenty-minute fix either. First off, make sure you relieve all that track tension properly before you even think about cracking bolts. When you’re putting the new one in, always take a good look at the track frame mounting points and the tensioning cylinder itself. A lot of guys forget to really inspect the track adjuster mechanism – if that’s sticky or worn, your brand-new idler won't last as long as it should. And for crying out loud, don't forget to pump some fresh grease into it if it's got a fitting.