Construction trucks

Manufacturers have done a lot to extend component life and service intervals for all types of big trucks, on and off road. As a result, today’s trucks spend more time working and less time in the shop than ever before. But without good maintenance and knowledgeable drivers the harsh realties of the off-road construction environment will chew up the best of trucks and leave you with expenses that could have been avoided.

Both highway and construction/vocational trucks are built to give the original owner around a million miles of service. But getting a million miles out of a Class 8 truck used in a construction application requires different maintenance practices than those used on their on-highway cousins.

Vocational and construction trucks are often asked to pull enormously heavy loads across rough and uneven terrain or soft underfoot conditions. They have to be geared to operate at highway speeds and yet crawl across a torn up construction landscape at a snail’s pace. Their engines are sometimes asked to breath dust-choked air. Axles and brakes can get dragged through mud and water. It’s a tough life. And while proper spec’ing can help you get a tough-enough truck, there is no spec in the world that’s tough enough to withstand negligent maintenance.

Given the high cost of big iron and the need to keep that iron moving productively, most construction equipment managers expect nothing but the best from their shop technicians. But when it comes to trucks, their relatively low cost and the fact that they are not often directly engaged in the profit-making side of the business means their maintenance can be put on the back burner.

“A big dozer or rubber-tire loader can cost in the high six figures and has to run everyday,” says Jim Fancher, marketing product manager for Volvo Trucks. “They want to make sure they get all of their money out of it. A heavy haul truck or tractor is a five-figure investment and it doesn’t do a whole lot between jobs and the owners are not as concerned. That’s probably the biggest reason why the rolling tractors get less attention.”

Neglect can be deadly
“The biggest problem with ignoring maintenance is going to be downtime at the worst possible time,” Fancher says. “It might not be an expensive breakdown but it’s going to happen when you least need it to happen. You’re hauling a D7 and all of a sudden the front wheel bearing goes out because nobody remembered to take a look at the hub and make sure there was lubrication in there or nobody checked the brakes and you’re at the end of the pads. Now the guy is overusing the Jake brake, he’s riding the brakes, he’s using his trailer brakes to maintain a safe speed coming down a mountain and the whole thing goes up in smoke.”

When it comes to construction companies and their haul trucks Rod McNulty, northeast region service manager for Peterbilt Motors Company, says preventive maintenance needs to be concise and proactive. “Draining the oil and greasing it does not do it justice,” McNulty says. “You have to look for things that have the potential for failure.”

It all starts with the walk around
Since construction haul trucks tend to be used intermittently for short periods of time, the walk-around inspection prior to taking the truck on the road is a key element in the service and maintenance program. The engine and drivetrain don’t accumulate hours between jobs, but that doesn’t mean the truck hasn’t changed.

“If you see something loose then you have to take care of it because, if not, it breaks. The driver needs to be very meticulous on the walkaround,” McNulty says. “The construction truck owner has to understand he’s working the truck hard and he needs to be cognizant of all the componentry on that vehicle. You’re putting it in a harsher environment – in and out of a pit or off road – using the components and suspensions and working your gearing a lot harder.”

Tires are a key part of the walk-around inspection. “Just because they look good and thump good, doesn’t mean you have good tire pressure, especially if you are running retreads,” McNulty says. “Under- or over-inflation is the worst enemy.”

A typical walk-around inspection of the tractor should take about 15 minutes, McNulty says. You may need a half hour if tires need inflating. In addition to the tires, you should also inspect the lights and the suspension and brake componentry. “It can be just a general inspection, making sure that all the pieces are where they should be and that nothing’s hanging off,” he says. “Any drying or rust marks on the slack adjusters may indicate that it isn’t operating properly.”

Next, inspect the steering componentry. “Make sure your cotter pins are in place and that everything appears to be tight, with no slop; that nothing has been making contact in the steering componentry,” says McNulty.

“The operators of these trucks get into heavy loading situations,” says Fancher. “It is critical that the driver or service people check out the vehicle before it goes into that application. The pre-operation checklist is crucial to the safe operation of the vehicle. Being in a rush can cost you.”

The muddy world of construction
While construction and heavy-haul trucks might not play in the mud all day like dozers and excavators, the time they do spend on construction sites can create additional maintenance needs.

“Contamination in the rear axles is probably more important in the vocational truck,” says Fancher. “If you back it into standing water, a stream or creek, you’re going to get water contamination at a percentage that’s too high to get boiled off by heat during normal operation.” Water, as well as dust and silica contamination, he says, can wipe out the bearings in short order.

The high level of contamination also creates issues regarding the use of synthetic lubes.

“The lubrication doesn’t necessarily break down in the rear axles because of the short mileage application,” says Fancher, “but how much lubrication are you getting if you have a lot of contamination? Sure you can drive it for three or four years. But is that really good for those components?”

Meeting the Peculiar needs of intermittent-duty vehicles
The intermittent, stop-start operation that most construction haul trucks undergo affects several component systems such that you need to change some service routines.

“If you’re not maintaining normal operating temperatures, that will produce a little more soot into the oils and break down those oils sooner,” McNulty says. “With intermittent operation you may be better off going with the time frame for service rather than the number of miles. Again, I would take an oil sample to verify.”

Coolant can also degrade over a long period of intermittent use. “Guys just don’t check the coolant to make sure proper levels are being maintained,” McNulty says. “It’s a very important aspect of the entire system and probably the most misunderstood and neglected. When you had major service at 150,000 miles it was common to replace all of the coolant with new. Now, with longer service intervals, the coolant gets less attention over longer periods of time.” Plus, topping off a little bit of coolant over a long period of time will dilute the additive package the system needs to fight corrosion and other problems.

Another component to keep your eye on, especially in dusty construction environments, is the air cleaner. An air filter restrictor indicator option is the best way to prevent dust from choking off your engine’s airflow.

Technology accelerates evolution of the low-maintenance truck
Better engineering, materials and manufacturing processes have helped increase the longevity and extend the time between rebuilds on most major truck components. And perhaps nothing has changed more dramatically than the durability of engines.

Twenty years ago, it wasn’t uncommon to do a full in-chassis engine rebuild, complete with bottom end bearings, at 150,000 miles, McNulty says. That was gradually extended out to 300,000 miles and with today’s componentry and oils and oil analysis you’re probably going to be looking at a general rebuild in the 500,000- to 600,000-mile range. “If somebody runs a good program and they use oil analysis to give them a snapshot of what the components are doing, then they may be able to stretch that out to 750,000 miles,” McNulty says.

The design of the newer trucks has also been continually refined to reduce and simplify maintenance chores and lower the cost of ownership. Air and electrical lines on many brands have been ganged and clearly labeled to eliminate the tangle of wires that confounded technicians in the past. Frames have been simplified to make it easier to modify bodies and reduce rust formation. Low-maintenance service hubs have also reduced maintenance intervals at the wheel ends. And computerized diagnostics have helped technicians cut to the chase when analyzing problems.

Transmissions going automatic
The evolution of heavy-haul trucks took a big leap forward about 10 years ago with the introduction of a new generation of automatic transmissions. In addition to reducing demands on drivers, the automatics make life easier in the shop too.

“You change the fluid and filter and generally don’t worry about it,” says Mitchell Murray, manager, North American market development for Allison Transmission. “The automatics also enable the U-joints and drive lines to live a lot longer. You don’t get near the drivetrain abuse. So the mechanics, instead of spending their time fighting fires, can spend time doing proactive stuff.”

The sophisticated electronics that govern automatic transmissions also allow them to be self-diagnosing, Murray says. “They will flash a code if there is a problem or if it’s severe enough it will force a person off the road.”

Murray says the environment and duty cycle for heavy haul trucks continues to get harsher for transmissions and this impacts your choice of automatic transmission fluid. “A lot of traffic and stop-and-go driving creates heat, and lubricants are being worked a lot harder than they used to,” he says. “In today’s environment I think it’s important to run synthetics that have guarantees. They’re not all created equal.”

Keeping an eye on new EGR engines
Starting in October of last year, truck engines manufactured by Cummins, Volvo, Detroit Diesel, Mack and Navistar began using exhaust gas recirculation, or EGR, engine technology to meet the EPA’s stringent exhaust emissions regulations. The recirculation of exhaust gas causes engines to run a bit hotter and puts more soot into the oil than their non-EGR counterparts.

The petroleum companies developed a new class of engine oils (CI-4) to meet these needs, but Fancher urges the owners of EGR-equipped trucks to be extra vigilant about oil changes. “If the engine oil change is scheduled at 15,000 miles, you want to have it in on time at 15,000 miles,” he says. “The most critical thing in any engine is the bearings and you want to keep them as well lubricated as possible.”