What is the best way to judge an Undercarriage?
Typically the first thing you see when you look at an Undercarriage (UC) is the track pads, these can be fairly easy to judge especially if you have seen other track pads on similar machines, but if you haven’t here is a quick run-down…
- Grouser height:
This is the cleat that makes contact with the ground, in almost every situation if this grouser is roughly the same height as the track pad bolt then the grousers are worn out.
- Track Pad:
In some situations the grouser may still look like it has some life left, but the leading edge of the track pad may be very sharp and the pad itself may be thin. This will allow the pad to flex or bend whenever you track over rocks or stumps and this will cause premature wear on the rest of the UC.
- Rails/Chains/Link assemblies:
This is the chain system that your track pads bolts to. It has a few moving parts, the link, pin and bushing. You can think of this as a bike chain with the main components being the same just on a larger scale. If you’ve ever ridden a bike you know how important this part can be. On a machine it is much more important to watch because if it gets loose or worn it can and will fall off. Then, you have a machine that will not move…
- Links:
These are not usually the first part to wear out on the chain, they should typically last the life of the UC. Look for sharp edges, or the bottom of the link where it makes contact with the other moving parts of the UC, if it is not flat but wavy it probably has wear.
- Bushings:
This is the part of the chain that comes in contact with the sprocket, it is usually the first part to wear out on the UC. But don’t worry, the bushings can be turned 180 degrees and you know have a fresh side of the bushing to wear.
- Pins:
This is what the bushing rides on and connects the links of the chain. These are typically sealed and lubricated to help them last longer, the seals can go bad causing the pin to wear out (this is common and very hard to see) best practice when you inspect a machine is to hop on the track with one foot on each side and rock left to right, if it is worn badly you will see and feel heavy movement.
- Sprockets:
Sprockets usually wear evenly with the bushings, if you see a sprocket and the pointed edge is sharp to the touch or rounded off it is most likely time to replace it.
- Rollers:
On most machines you have 1 or 2 carrier rollers, these are the rollers on the top side of the roller/track frame that keep your tracks from rubbing on the track frame. These will start to roll where the link makes contact the more it rolls, the more worn it is, when they are new the will be flat. When it comes to rollers the same judgement is used for the bottom rollers, bottom rollers wear faster because they have more contact with the material you work in and they carry the weight of the machine.
- Idlers:
This is the round wheel in the front of the track frame that helps keep the track in place, and also with the help of grease and the track adjuster keep the track at the correct tension to avoid premature wear, it shows wear like the carrier rollers, if it is rounded on the edges or shows to have sharp edges it probably has some pretty substantial wear.
Supporting Images
When it comes to judgement on the UC, all machines are different… From dozers to excavators, all track machines wear differently especially depending on the material and soil conditions you work in.
When I judge a UC on a machine I try to use my best guess on a percentage, for example: If I say the machine has a 60% UC this means that the pins and bushings are very close to needing to be turned along with sprockets being replaced.
I hope this helps, I am always open to answering questions. Have more questions? Send us a message
Back to Top
Why buy a used machine?
It’s just like a recreational toy, let someone else take the hit on depreciation! If you have some history and you know the machine was cared for, then it will be as good as new for you, as long as you care for it like it makes a living for you.
Back to Top
