Maximizing Undercarriage Lifespan: Tips for Equipment Managers

It has been said that 20% of the cost of a new machine is the undercarriage system and then the undercarriage becomes 50% of the maintenance budget.

For managers with a fleet of crawlers, whether it be dozers, excavators, CTLs, or all of them, keeping that cost down is important. Dealerships can help.

Indiana and Michigan Caterpillar dealer MacAllister Cat has a good primer on undercarriage maintenance and care.

There’s more to undercarriage maintenance than performing routine undercarriage inspections. The two primary undercarriage management principles are keep it clean and maintain the appropriate tension.

Beyond these two tenets, there are a number of factors that can impact the wear of equipment over time, including application, the terrain, operator techniques, and using the right tracks for the job.

Steel versus rubber

Deere CTL — Rubber tracks are best for soft conditions and a lighter footprint; however, track tension remains important for optimum performance and reducing wear.

Most large equipment such as hydraulic excavators and dozers uses steel track for propulsion, traction, and stability. There’s no substitute for metal tracks when it comes to durability. Steel is strong and long lasting; however, steel tracks can tear up work surfaces and cause damage. Metal pads with steel grousers are made to cut into the ground so they can propel equipment and let it do what it’s designed for. For more sensitive applications, there’s the rubber alternative.

Rubber, rarely found on large equipment, is a highly flexible material, and it can be tough when necessary. However, there’s a limit to what rubber tracks can support. For work on soft ground like turf or finished surfaces like concrete, it’s wise to select rubber tracks. Rubber tracks are ideal for small-sized excavators and compact track loaders where a light footprint is needed.

Although steel or rubber tracks might be reliable within their designed life span, undercarriage is always vulnerable. The undercarriage is a complicated system of moving parts, and it requires special attention to prevent failure.

Pay close attention to undercarriage parts as well as what tracks reveal. An important part of a maintenance program is understanding the factors affecting undercarriage wear and what can be done to prevent premature wear-out.

What factors affect undercarriage wear?

All undercarriage components naturally wear out over time, and they have limited service expectancy. Although service life is measured in operating hours, there is no set rate for how long the undercarriage will last. Component lifespan greatly depends on a variety of factors on job sites. Here are the main factors affecting undercarriage wear.

Applications have an enormous impact on the stress and strain placed on parts. Typical site applications include excavating or trenching, dozing or pushing, ripping, loading, carrying, and grading. Some applications place more strain on the undercarriage than others. The key factor is the torque transferred from the power component through the drive system. As a rule, the more torque required for the job, the more wear will be placed on the undercarriage.

It’s rare to control the terrain the equipment faces. Usually, it’s there to change the terrain. It has to work within preset conditions, and some of those conditions can test undercarriage limits. Terrain wear comes from working on hills, slopes, crowns, and depressions. It’s the resistance force the undercarriage experiences from changing terrain that can wear components.

Along with challenging terrain is the underfoot conditions the undercarriage experiences. Tracks take the front line of abuse from abrasive rocks and harsh debris. The tracks can then transmit underfoot material into the undercarriage, causing wear. Underfoot conditions like sand might seem soft and easy on the tracks, whether they’re rubber or steel. However, sand is very abrasive, and it grinds away at moving undercarriage parts, causing high wear and shortened life. The trick to undercarriage survival from underfoot threat is constant cleaning.

Application, terrain, and underfoot conditions aren’t the only threats to undercarriage. Plenty of wear comes from how the equipment is operated. Aggressive operation is a big factor affecting undercarriage wear.

Managers can prevent unnecessary undercarriage wear by training operators to run equipment responsibly. Operator wear can be minimized through monitoring.

Operator mistakes that wear out undercarriage

Most equipment operators don’t intend to do harm. Operator harm often comes from inexperience or lack of proper training. The main mistakes that wear out equipment undercarriages include:

Operating aggressively to get the job done quickly
Traveling too fast for site conditions or the designated speed limit
Placing excavation force on the rear drive sprocket instead of front idlers
Digging from the equipment’s side and placing cross tension on undercarriages
Slipping or spinning the tracks in soft underfoot and terrain conditions
Turning the equipment continuously in one direction and not alternating turns
Traveling in reverse unnecessarily, which places wrong-directional force on drives
Operating on grades and slopes instead of leveling equipment to equalize force.

Curing operators of these tendencies is a great start, and any effort put into educating operators and having them become part of an undercarriage maintenance program will be rewarding. One of the main steps they can take is to perform daily undercarriage inspections.

If equipment operators have a personal stake in the fleet, they’re much more likely to treat it right. They’ll pay attention to proper operating procedures like avoiding side-stress on undercarriages and not placing excavation force on rear drives. They’ll travel at sufficient speeds to work productively but slow enough to save wear on components.

Encourage operators to report potential problems immediately. Chances are they’ve usually spotted the issue through a daily undercarriage inspection.

Inspections don’t take much time, but they have long-term payoffs. Here are the main points to check when doing a daily undercarriage inspection:

Stand back and have a general look to identify anything that appears out of place.
Walk a circle around equipment before looking at individual parts.
Look for oil leakage or any unnatural wetness that may be dripping down.
Give a further look to leaking seals or damaged grease fittings.
Check sprockets for teeth wear and bolts that are backing off.
Inspect idlers, guide plates, rollers and links for loose or missing parts.
Watch undercarriage frames for signs of stress cracking.
Check the undercarriage rails and look for indentation wear.

The undercarriage isn’t the only part of the equipment to check in a daily inspection. Track problems are often early indicators of issues caused by undercarriage problems. Here’s what to inspect on tracks daily:

Correct any cracked, broken or loose shoes and replace missing shoes immediately
Check for track tension and follow the tolerances set in equipment manual
Watch for track alignment that shows an inward or outward travel tendency
Inspect shoe wear on leading and trailing edges as well as traction bar wearing
Start equipment and slowly spin each track while monitoring performance
Look for any cracking or fraying if you have rubber tracks
Examine steel tracks for corrosion or metal fatigue.

Most equipment manufacturers and operators consider tracks a slightly separate entity from true undercarriage components like sprockets, drives, links, rollers, and idlers. Both tracks and undercarriage assemblies are technically separate systems, but each one supports the other.

The undercarriage needs low wear and freely moving parts to perform well, and that starts with making sure you adjust the track tension.

How to adjust track tension

Excavators in rock — Working in and around rock can be perilous for undercarriages.

Track tension needs to be a perfect balance of not-too-tight and not-too-loose. This can be tricky to achieve, and proper track tension depends on certain factors.

If tracks are tight, they’ll place unnecessary resistance on undercarriage components. Every moving and stationary part of the undercarriage will be stressed. That leads to early wear and costly repairs.

If tracks are too loose, they’ll also place stress on your undercarriage. Loose tracks will wander and go out of alignment, placing side stresses on your system. As with being too tight, loose tracks wear out your undercarriage and can incurr unnecessary costs.

Setting the right track tension depends on a variety of factors. Track tension is a matter of specific equipment design, individual track type, and actual working conditions. The main factors concerning track tension are track type, equipment size, underfoot conditions, and environmental influences such as high or low temparatures and seasonal variants.

The best step to take is referring to the original equipment manufacturer’s manual that comes with the equipment.

Sag is the dip or drop seen in the track at the upper plane where it’s not affected by ground compression. The manufacturer will have a sag guide table that gives ideal tolerances for track tension.

Don't be surprised to find a lot of variance in track tension tolerances. Big excavators with standard sprocket designs and large steel tracks have different sag rates than rubber-equipped compact track loaders with elevated sprocket designs. When in doubt about track tensions, always contact the equipment dealer for professional advice.

Professional advice from a reputable dealer will save a lot of headaches when it comes to undercarriage issues. They know the tension tolerances needed for top performance.

Specifying track size and shoe

It’s always important to bring up track and shoe size when talking about undercarriage maintenance. Having the proper track width and shoe size for the task has a big effect on performance. If a track and shoe combination is oversized, the unnecessary weight and bulk will wear undercarriage components. If the track and shoe assembly is too small, the flotation rate will suffer, and so will the undercarriage.

The rule to follow is always use the narrowest shoe and track width possible. Adequate floatation is necessary for terrain and underfoot conditions, but don’t exceed the optimum rate. An oversized track and shoe assembly can cause these undercarriage issues:

Increased sprocket and busing wear
Increased wear on flanges, idlers, rollers, and links
Loose pins and shoe hardware
Track joint life reduction
Broken shoes and track with failed undercarriage components.

Dealers are available to discuss any aspect of track and undercarriage care and maintenance. Partnering with them can be a cost-saving move in itself. Miller Bros. fleet manager Jon Kaye is an advocate of dealer help on undercarriage.

"I think as much communication as you can give them and include them in our business, the more beneficial that can be," Kaye said. "If you go back to the use of undercarriage, we can include them in the process of not only helping us measure our undercarriage, but also to keep track of its life. When a dealer wants to do that for you, yeah, they want to sell you an undercarriage. But in reality you're getting free labor. They're willing to drive around, inspect your undercarriage, and give you reports.

"The benefit to to us is we get that done for free, the benefit to them is they can actually determine how many machines in our market need undercarriages and put bulk orders together, which in turn saves us money," Kaye said. "I think the more they understand what our business needs and how we need it, the more they're willing to respond."