Undercarriage Parts

Are Our Track Links Greased?

All our chains from 154mm pitch and up (7ton +) are greased and sealed guaranteeing longer service life than the unsealed type. The advantages of sealed track links are:

• The seals prevent soil infiltration and keep the grease in the track links.
• The grease is vacuumed in at assembly ensuring most of cavity is filled with grease.
• Reduces noise and friction thus preventing premature wear.

The Superseal option is all the above and adding the benefit of innovative seal greatly reducing the risk of seizing and premature internal wear.

A track link is worn when there is so much play between the pin and the bushing that other undercarriage components start to wear. An increase in pitch creates more play between the pin and the bushing. This makes the inside of the bushing oval and the pin becomes thinner, because it rubs against the bushing wall. This makes the track link longer. You can recognise an increase in pitch by e.g. the following visible characteristics:

• The points of the sprockets or segments become sharp, this is a sign that the track link no longer runs in line with the sprocket hollow due to an increase in pitch.
• The front idler and the guide arms become fully extended and are visible from the frame housing.
• The spaces between the track shoes and the links open up.
• Measure the track pin centres over 4 x pitch (over 5 Pins), give us a call and we can advise on how much wear is remaining.
• If the bushes have worn through to the pins, this is an extreme case of wear and certainly time to replace.

As the Excavator (or Dozer) tracks, the chain flexes around the sprocket and idler at each end of the track. This causes the pin to rotate inside the bush of the chain. For the early phase of chain life, there is grease separating the pin and inside of the bush. However, as the seals retaining the grease deteriorate and the grease is gradually lost, this allows steel on steel contact, wearing out the pin and the inside of the bush, resulting in a longer distance between each pin (or link), which extends the overall length of the chain.

Seized chains are the most frustrating thing you can experience and can happen on a near new machine.
Seizing is caused by when water enters into the grease cavity and reacts with the grease and forms a black gunpowder material which locks the joints, sometimes called arthritis or bunching up.

• Track links wear on the idler running surface. A specified measurement from the centre rib to the running surface defines when the idler is 100% worn out. This measurement varies between digger types and sizes, please give us a call and we can provide what measurement is required based on your excavator.
• If the sides of the grouser (centre rib) show signs of side wear, or the idler rubs against the side of the frame, then the track link is not in line with the idler. This may be caused by a cracked frame, worn mounting arms, worn slide in the frame, a broken axle, or a defective tension device.
• If the bearing is defective and has lost oil, idler will need replacing immediately before there is further damage to any other components.

Sprockets should always run in line with the chain’s pitch. If the sprocket is worn, the points of the gear ring will become sharp. This is because there is play between the pins and the bushings.

Another common wear pattern for sprockets and segments is the lateral wear. This is caused by (among others) worn chain guides, a twisted undercarriage, or poor guiding of the front wheel. It can also be caused by the filtration of hard materials between the bushings and the sprockets, or by incorrect alignment. To limit wear from the infiltration of soil (packing), we make sand notches in our sprockets.

Sometimes the machine’s sprockets are sharp, but the track links appear to be in reasonable condition. We are frequently asked whether the sprockets still need to be changed. The only reason why a sprocket becomes sharp is through the chain’s increased pitch. An increase in pitch creates more play between the pin and the bushing. As a result, the chain’s bushing no longer runs in line with the hollow part of the sprocket. This causes wear on the sprockets and the points become sharp. So, if replacing very worn sprockets without replacing the chains the bushes on the chain will load up the points of the teeth and will cause banging or jumping of the chain damaging the drive motors, sprockets, and chains. Same when replacing new chains always replace with new sprockets.

• With very worn rollers, fitting new sprockets will put extra weight on the drive motor causing vibration which will result in damage to the machine and sprockets. It is advised that you check your rollers to avoid this problem.
• It is also recommended to fit with new sprocket bolts, grade 10.9 and torque to the Machines specifications. This is due to the fact that over time they can corrode and lose their retention resulting in damage to sprockets and the hub.

• Top and Bottom rollers wear on the running surface which reduces the diameter of the roller, a specific measurement of the running surface diameter defines when the roller is 100% run out. This measurement varies between digger types and sizes, please give us a call and we can provide what measurement is required based on your excavator.
• The flanges wear if you’re doing a lot of hillside work and is increased significantly if track guards are not fitted and maintained to the right tolerance.

When working in extreme conditions, bottom rollers can be fitted to the top to utilise the outer flanges and stronger mounting to the track frame. It is important to clean around the top roller regularly to ensure it can turn easily, this will eliminate flat wear spots. Ensure the top roller mounting is not bent, and the roller it level and the chain is running evenly on each side of the flange.

Bottom rollers provide for the undercarriage clearance height. The combination of the link height and the installation height of the bottom roller defines the undercarriage height. There is consequently no load on the front idler, the sprocket or the final drive. When the chain links and the bottom rollers wear, the machine’s undercarriage will drop, so that the load is exerted on the front idler, the sprocket and the drive motor. It is always recommended to replace idlers and bottom rollers as a set so that the machine weight is not carried by a singular roller as this will void warranty and cause premature failure.

It depends on the wear on the running surface of the roller. The machine weight is carried by the rollers and if you replace a new roller on a worn out set this will carry the weight of the machine and can fail prematurely. West-Trak recommend to replace an entire set of track rollers at the same time. An alternative is to replace only one side of rollers, and move the remaining rollers to the other side of the machine.

An excavator’s track shoes need to be replaced when the bolt heads are at the same height as the track shoe grousers. The bolt heads are never intended to bear the weight from the machine, if used beyond this point, the shoes could come loose and will damage the chain.

If the shoes on your excavator are bent or bending, it’s most likely due to the fact that they are too wide for the application or that they have worn out.

A track shoe width should be adjusted to suit the terrain on which the machine is working. The more width gives you more flotation and versatility but less manoeuvrability and structural life. The wider the shoes, the higher the pressure on the links between the pins and the bushings. A track shoe that is too big will increase the wear process of all undercarriage parts and consequently increase the chance of a chain breakage.

We have track shoes available between 250-960mm long.

Feel free to give us a call to discuss what shoe size is best for you.

3 Bar Shoes are the most common and best for general working conditions, they are strong and have minimal soil disruption.

2 Bar Shoes are the strongest, these have round mud holes to clear soil compaction in the chain cavity. They are the best for Rock and high impact conditions, sometimes used in forestry as well.

1 Bar Shoe has the best traction, these come with trapezoidal mud holes to clear soil compaction in the chain cavity. Primary these are forestry shoes for steep hill country. They are available as non clipped or clipped corners. The purpose of clipped corners is to help machine movability and machine under body clearance on self-levelling machines. Clipped corners do reduce the side traction on steep hill slopes.

We recommend to always replace track, sprocket, and track roller bolts and nuts when replacing worn parts on your excavator, dozer, or tracked machine. In 90% of cases, reusing track hardware results in loose shoes which will enlarge the bolt holes in the track shoes, causing the links to become damaged as well. This means that the track shoes and possibly the track link will need to be replaced and will void warranty.

Yes, the best time is when it’s is all apart and it’s not a big cost. When you put new track gear on especially when you have new shoes it will put more tension on the Adjusters and often the old seal will fail.

West-Trak recommend you take every precaution when removing or handling old track adjusters. With years of wear and tear there can be damage to the threaded nut holding the spring in place or the centre shaft may even be cracked. They have been known to explode apart even when carrying them around with the forklift.

Track guards Ensure your track chains run straight and true all day every day, saving the wear on roller flanges, sprockets and the chain rails. They help align the sprocket to the centre of the chain reducing the risk of the sprocket’s teeth grinding the inside of the chain rails.

We recommend you have 2 Track Guards per side on all 6 -14 tonne excavators. From 16 tons up we recommend 3 Track Guards. The quantity required will vary depending on your working conditions. The West-Trak team can advise the right quantity of Track Guards for your machine.

When you place Track Guards on new chains you can expect to save up to 30% wear on chains, sprockets, and rollers.

We suggest if you are doing Civil Construction work with not a lot of tracking and working only on level ground these two standard Track Guards will be sufficient.

However, if you are using your machine in more of a heavy situation and are doing more tracking and operating on steeper terrain, we suggest adding an extra Track Guard to each side on a 6-14 ton machine and an extra 2 each side on machines from 16 tons up.