Caterpillar 303.5 303CR Aftermarket Idler

This is the replacement aftermarket idler for the following Caterpillar mini excavators:

• Cat 303.5 must verify size
• Cat 303 CR 
• Cat 302.5 must verify size

The front idler installs on the opposite end of the undercarriage from the sprocket and this is the part that expands out as you pump the grease in the tensioner to tighten the rubber track. Some people refer to this larger roller as the pulley.

This idler is also known to fit on some Caterpillar 302.5 models. This idler has ten and a half inch long mounting arms which is the only difference. If your mounting arms that slide into the track frame are shorter than ten and a half inches then you need the alternate part number 140-4009. Give us a call if you have any questions.

Cat 303.5 Undercarriage

• Idler 140-4009 or 172-2017 (must verify serial and specs)
• Sprocket146-4022
• Top Roller 146-6064
• Bottom Roller 185-7280