Three Things We Need to Manage During the Life of an Undercarriage
In my previous article, I looked at some of the KPIs that help us understand whether we’re managing undercarriage life successfully.
These included Percent Worn at Removal, Component Life Achieved, planned versus unplanned replacement and ultimately Cost per Hour.
But KPIs measure the result.
What do we actually need to do during the life of the undercarriage to achieve those results?
There are three areas that come up repeatedly when managing undercarriage:
1. Midlife Tasks
2. End-of-Life Replacement
3. Identifying and Correcting Accelerated Wear
Regular undercarriage inspections provide the information needed to manage all three.
1. Midlife Tasks – Helping the Whole System Reach Its Potential Life
We generally carry out midlife tasks when the undercarriage is somewhere between 50% and 75% worn.
Depending on the machine and operating conditions, these may include:
- Replacing segments
- Regrousering shoes
- Swapping idlers
- Changing track roller positions
The reason for doing this work is important.
Not every component in an undercarriage system wears at the same rate.
If we do nothing, one component may reach the end of its life while other expensive components still have considerable usable wear remaining.
For example, without a pin and bush turn, the bushes might reach 110% worn while the links are only 65% worn.
If the chain then has to come off, the remaining 35% of usable link wear goes into the scrap bin.
That 35% has been paid for, just not used.
The purpose of midlife maintenance is therefore to deal with the components that are getting ahead of the rest of the system and allow the complete undercarriage to continue towards its full potential life.
The Required Midlife Work Will Vary
Every operating environment is different.
- Wet, sandy conditions may produce high bush and segment wear.
- Hard, abrasive underfoot conditions may result in higher grouser wear.
- Heavy blade loading or blade hang-up can increase wear around the front idler and the first few track rollers.
There isn’t necessarily one standard midlife maintenance plan that works everywhere.
The wear patterns should tell us what work is required.
The important part is identifying it early enough to plan and complete the work before the faster-wearing components have gone too far.
Regular inspections and wear forecasting make this possible.
2. End of Life – How Far Should We Run It?
At the other end of the undercarriage lifecycle, we have a different challenge.
We want to get as much usable life as reasonably possible from the components.
But we don’t want to achieve that extra life by damaging everything around them.
Ideally, the overall undercarriage system reaches as close as practical to 100% worn.
Individual components, however, behave differently around their wear limits.
Links generally cannot be operated much beyond their practical wear limit.
Track rollers may continue operating considerably beyond 100% worn and still function, but eventually this can start causing damage to the track frame, chain guards and surrounding components.
So there is a balance.
Remove the undercarriage too early and we throw usable undercarriage life away.
Run it too long and the additional life can be outweighed by consequential damage.
The objective is to find the best point between the two.
End-of-Life Work Needs to Be Planned Well in Advance
Knowing approximately when the undercarriage will reach the end of its life gives the maintenance team time to prepare.
The change-out can potentially be aligned with a planned PM service or shutdown, reducing additional machine downtime and the impact on production.
Replacement chains, rollers, idlers and other components can be ordered and be available when required.
This is particularly important where supply chains are long.
The track frame rebuild should also form part of this planning, and if a swing frame is required, this can be prepared and ready to install.
Regular undercarriage inspections, including frame condition inspections, provide the information needed to forecast when the undercarriage will need replacing and what work is likely to be required on the frame when it comes off.
The objective is straightforward:
Get as much useful life as possible from the components without creating unnecessary damage to the frame or surrounding components.
That is what ultimately helps improve Cost per Hour.
3. Accelerated Wear – The Event That Can Destroy the Plan
Midlife work can be planned.
End-of-life replacement can be planned.
Accelerated wear is what can destroy both plans.
A component that was expected to last another 2,000 hours can suddenly start wearing considerably faster than it did previously.
There are many possible causes.
What is important is identifying the change early.
Some of the things we should be looking for during an inspection include:
- Wear rates increasing since the previous inspection
- Bright or freshly exposed metal
- New wear marks
- Abnormal contact between components
- Changes in established wear patterns
- Missing or loose hardware
- Misalignment
- Damage that wasn’t present at the previous inspection
This is also why I believe photographs should form an important part of an undercarriage inspection.
Measurements tell us how much something has worn.
Photographs can help us understand why it is wearing.
Taking multiple, consistent photographs at each inspection provides a visual history and makes changes much easier to identify.
The Cost of Accelerated Wear Is Often Hidden
This is an area that I think deserves more attention.
The cost of accelerated wear isn’t necessarily the cost of replacing the component where the problem started.
If the problem continues, it may accelerate the wear of other components.
Eventually, a relatively small problem can result in an entire undercarriage system being removed earlier than planned.
Suppose an undercarriage expected to achieve 8,000 hours has to be replaced at 6,500 hours because accelerated wear wasn’t identified and corrected.
The mine doesn’t receive an invoice saying:
“Cost of 1,500 hours of undercarriage life lost.”
But the cost is real.
It appears later as a higher Cost per Hour.
This is one of the hidden costs of undercarriage management.
Inspections Are Only Valuable If We Use the Information
This brings us back to the KPIs discussed in my previous article.
Percent Worn at Removal doesn’t improve because we measure it.
Component Life Achieved doesn’t improve because we put it on a dashboard.
Cost per Hour doesn’t improve simply because we calculate it.
The results improve when we use the inspection information to make better decisions during the life of the undercarriage.
At Midlife, identify which components need attention so the whole system can continue towards its potential life.
At End of Life, forecast the replacement early enough to maximise usable life, protect the frame and plan the work around production.
And throughout the entire life of the undercarriage, look for accelerated wear and correct the cause before it changes the plan.
The objective isn’t simply to inspect the undercarriage.
The objective is to use the inspection to get as much useful life as practical from the complete undercarriage system, with minimal disruption to production and without creating unnecessary damage to the machine.
And if we are doing that successfully, the KPIs should show it.
If your inspection data isn’t telling you when to act on midlife work, end of life or accelerated wear, let’s talk.
Get In Touch with us and we’ll look at how your fleet is being inspected today.