Store

Caterpillar 303.5 303CR 172-2017 Idler

172-2017 Cat 303.5 Idlers
Rubbertrax
Caterpillar 303.5 303CR 172-2017 Idler
Buy aftermarket tension idlers for the Caterpillar 303.5 and 303CR mini excavators online and save versus buying from your local dealer. This idler is also known to fit some 302.5 models depending on your serial number. See below for important fitment verification.
SKU: 172-2017AM
Weight: 62 lbs
Price: $500.00

Free Shipping Across the USA

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 tension 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.


The mounting arms for each series vary, however the idler wheel is universal so we are currently selling the idler wheel separately without the mounting arms so you can reuse your existing arms for a guaranteed fit. The mounting arms (yokes) are ten and a half inches long on some models. There is a shorter version under part number 140-4009. Reusing the mounting brackets is common among many manufactures and most dealerships sell the idler wheel individually.


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