under carriage

[Don Henry]

whena individual says the undercarriage is 80% or 50% what are they talking apart. What parts on the dozer relates to this question

 

[Anonymous-0]

Might be % worn or remaining. Have to be sure what they mean. There are wear charts and are expressed in % wear from new to 100% worn to rebuild limit. Idlers, rollers, chain Pin and bushing and rail height wear. Run sprockets untill sharp tooth. Undercarrage all works together so should do a complete job or some old parts may accelerate wear of new parts. A worn track chain with a long pitch from worn pins and bushings will wear a new sprocket out fast.
Later Bob

 

[Lavoy]

If you had a true undercarriage inspection, it would be roller wear, link wear, pin and bushing wear, track pitch, sprocket wear, front idler wear, upper idler wear and some other I have forgotten done by a mechanic. The process for doing it is kind of lengthy and involves lots of measuring. It has been my experience, that most of the time when you see percentages listed, it is a quick guess made by someone, and may or may not have any relavance to actual wear.
Lavoy
JDCRAWLERS.COM

 

[Fordman6442]

Undercarriage is related to all the moving parts of the track system. Front idlers, sprockets, track chains, pads, bottom rollers,
and carrier rollers. Percentage relates to wear left on the components.
Don from Canada

 

[kyhayman]

It typically means nothing. Most people dont actually measure the components when they sell a machine, they estimate that it has 70-80 percent life left, etc. But, they dont specify if that is life left to manufactorers recommended replacement or life left to 'run to destruction' of the component.

The last little machine I bought, the seller was a pretty reputable dealer. His broad comment was, its got 50 pecent undercarriage with the rails looking at needing service in about 1000 hours and the rollers and sprokets having about 2000 hours left in them. I found those estimates to be a little low.

 

[AJ.]

Go to the link below, it will take you to a site that gives all the information you will ever need to know about undercarriage,you can download the file.
AJ
About Tracks

 

[Don Henry]

thanks to everyone this is a awesome site, i have been a mechanical engineer for 28 years spending a good deal of that time in the mining of mostly agg. & sand. Companies like Terex i.e. Cedarapids Inc., Hewitt Robins, Nordberg, Metso, El-Jay, J.C.I.
If any questions in that field comes up i would be glad to help, inspect, engineer.

Thanks to all.

 

[Lou from Wi.]

AJ. DID the down load. Thanks it does explain a lot. Information will come in handy when we get to the O.C.46 crawler tracks.
LOU.

 

[M Diesel]

(quoted from post at 20:35:42 01/30/10) thanks to everyone this is a awesome site, i have been a mechanical engineer for 28 years spending a good deal of that time in the mining of mostly agg. & sand. Companies like Terex i.e. Cedarapids Inc., Hewitt Robins, Nordberg, Metso, El-Jay, J.C.I.
If any questions in that field comes up i would be glad to help, inspect, engineer.

Thanks to all.

Don, what 80% really means is totally shot. It is almost always uttered by a seller that has never seen a track gauge, and thinks the grousers look okay to him. You will rarely ever see a number listed lower than 50%. More often than not though you will find wear in the minus range, as in below 0% remaining. As in 50 to 100% below. Those are in what is called run to destruction phase. They can't be built back up again when compared against replacement cost.

Also, various wear items will wear at different rates depending on what the machine is doing, what soils it is working in. Some will wear pins/bushes quickly (sand especially), others will wear down rail and roller surfaces (scraper duty, or lots of turning). Side hill work will take off roller flanges at an amazing rate. Add in that old machines have had parts replaced at various times means you often end up with a hodge podge mix of parts worn to different amounts. It isn't rocket science at all, but does take a little education in recognizing the various symptoms, knowing what to look for.