Oversized Idler on 420C

General help and support for your Lindeman through 2010 John Deere crawler
Post Reply
420C-Mike
40C crawler
40C crawler
Posts: 17
Joined: Mon Apr 27, 2015 5:59 pm
Location: Milwaukee

Oversized Idler on 420C

Post by 420C-Mike » Mon Sep 12, 2016 1:45 pm

I was recently at a salvage yard and found a 420C Idler and tension spring assembly that I couldn't pass up only to realize when I got it home that it was the Oversized Idler.

What was the purpose of the oversized idler? Intuition says it was for worn pins and bushings but the parts book shows it with an additional link in the belt?

Appreciate some history and insight

User avatar
Lavoy
Site Admin
Site Admin
Posts: 9377
Joined: Sun Apr 03, 2005 8:32 pm
Location: North Dakota
Contact:

Post by Lavoy » Mon Sep 12, 2016 2:34 pm

Standard idler is what often times is referred to as an "ag" idler. On an agricultural crawler doing field work, the crawler rides better on an ag idler because it is undersize so the front of the track is climbing up at a slight angle from the ground. The drawback to this is where you have a front end load like a dozer or loader. With an ag idler, the "fulcrum" if you will is the most forward bottom roller. With a full size front idler, this then becomes the idler itself, and you have in effect lengthened your wheel base, and moved the tipping point significantly forward. This make the crawler more stable, as well as increasing foot print to some degree. Standard idler was never available on 5 roller crawlers, they always came with full size idler. Idler size was only an option on 4 roller crawlers, and then only on the two cylinder crawlers to the best of my knowledge.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com

User avatar
mapaduke@yahoo.com
1010 crawler
1010 crawler
Posts: 420
Joined: Sun Sep 13, 2009 6:27 pm
Location: Rochester N.H.

Post by mapaduke@yahoo.com » Tue Sep 13, 2016 5:48 pm

Great explanation Lavoy.
nothing crawles like a deere

User avatar
shugy368
430 crawler
430 crawler
Posts: 55
Joined: Tue May 17, 2016 12:40 pm
Location: Monterey Bay Ca.

idler size

Post by shugy368 » Tue Oct 11, 2016 1:39 pm

I own a 420-C loader how do I determine the idler is an AG mod or oversize?

User avatar
Lavoy
Site Admin
Site Admin
Posts: 9377
Joined: Sun Apr 03, 2005 8:32 pm
Location: North Dakota
Contact:

Post by Lavoy » Tue Oct 11, 2016 1:51 pm

Most loader crawlers are 5 roller, all 5 roller crawlers are full size idler.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com

User avatar
shugy368
430 crawler
430 crawler
Posts: 55
Joined: Tue May 17, 2016 12:40 pm
Location: Monterey Bay Ca.

idler size

Post by shugy368 » Tue Oct 11, 2016 3:55 pm

I should have known you would have the answer Lavoy :lol: Thanks and my 5 rollers are rolling along nicely thanks to you and all the other knowledge that permeates this site 8)

User avatar
Lavoy
Site Admin
Site Admin
Posts: 9377
Joined: Sun Apr 03, 2005 8:32 pm
Location: North Dakota
Contact:

Post by Lavoy » Tue Oct 11, 2016 9:25 pm

No problem.
Lavoy
Parts and restoration for antique and late model John Deere crawlers.
Owner and moderator www.jdcrawlers.com

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests