While most big diesel-powered construction machines move dirt or rock, the wheel loader is called upon to work in a diverse range of environments. Many of these are harsh or severe-duty environments and failure to spec a wheel loader to meet these demanding conditions can result in premature component failure and costly downtime.
The key to enabling your wheel loader to survive in severe environments is to recognize the hazards and spec the machine accordingly. Just keep in mind this can be a very detailed process. According to Gary Bell, vice-president and general manager for Kawasaki, the package for wheel loaders in some applications may include up to 35 or 40 options. “You almost have to custom design them,” Bell says. “It’s not a cookie cutter approach.”
Even if you don’t work your loaders in a severe application, there is a lot you can learn from those who do, mainly this: You need to know to the second what your cycle times are, to the pound what weights you’ll carry, and you have to analyze every hazard on your jobsites in order to correctly spec your machines. Here is a look at some of the most difficult applications and the best practices smart wheel loader owners employ to get the most out of their machines.
Wheel loaders get plenty of work in quarries and owners of machines in these environments have to be careful about two particular hazards: airborne dust and sharp rocks. Any kind of dust will clog filters and radiators, but abrasive dust containing a high silica or quartz content can also wreak havoc with radiators. And with radiators on some of the bigger loaders costing up to $60,000, the penalty for ignoring this hazard is steep.
A wheel loader with a blower type fan can send a high velocity stream of abrasive grit blasting across the thin leading edges of the radiator’s cooling fins. Once the fins begin to leak there is no choice but to replace the entire radiator.
There are two solutions, says Lee Haak, wheel loader product manager for Komatsu. You can spec what’s called an armor-core radiator. On these the leading edge of the cooling fins are wrapped with a micro-thin piece of steel that’s much harder than the aluminum or brass used for conventional radiator fins. Or you can install a blast grid between the fan and the radiator, which slows down the abrasive particles before they hit the radiator. Choosing one or the other of these two options usually requires a technical analysis of the site conditions, Haak says, but either can double the life of your radiator in areas where abrasive dust exists.
Tires can also suffer in quarries where sharp rock is present in certain sizes. To prevent blowouts and rock cuts some operators will wrap all four tires in chains.
Landfills, recycling and transfer stations
Airborne dust and debris can also pose problems for wheel loader cooling systems in landfills, transfer stations and some recycling operations. Small bits of plastic get stirred up and melt onto the radiator fins. Old sofas and upholstery create a snowstorm of cotton fluff. Bigger pieces of paper and plastic lodge against the fan housing or get stuck between the radiator cores.
The first design goal for these loaders is to redirect the airflow so that trash isn’t sucked up from under the machine, says Xenya Mucha, solid waste market manager for John Deere Construction Equipment. “You try to take the cleaner air above the tractor,” she says, “which also helps keep it cooler.”
Another strategy is to use a hydraulically driven reversing fan that blows debris off the radiator. These are set up with a timer. The operator can also actuate the fan at any time, but that cycle will kick in whenever the engine slows down to 180 rpm, and the timer will continue to cycle at the programmed time, Mucha says. Swing-out radiators are also easier to keep clean. And putting the air conditioning condenser on the top of the cab eliminates the problem of debris getting stuck between the two cooling cores.
Transfer stations with their asphalt or concrete floors can also be hard on tires, Haak says. Here you may need to spec foam-filled or semi-solid rubber tires, he says. These floors are frequently slick, he adds, which makes adjustable rimpull desirable. “We’ve had some users ask us to take first gear completely out of the machine,” he says, “so being able to change the aggressiveness of the transmission helps.”
Many transfer stations also run double shifts. If you are running your loader through a 16-hour day it may make sense to consider extended drain oils and lubes to cut your maintenance-related downtime and save money on oil changes.
Perhaps the most punishing environment a wheel loader can face is carrying hot slag in a foundry. “Hot slag comes out as a residue of ash mixed with molten steel,” Bell says. This demands a full package of protective options, some of which includes a hot slag bucket with a 4-inch lip, epoxy paint, tempered glass, metal windshield retainers, stainless-steel brake lines and cylinder seal protectors. Fire shields must also be installed to protect cylinders, fuel lines, hydraulic hoses and wiring and the hydraulic tank and fuel tanks must be guarded. Steel cable ladders are often used and a remote engine shutdown is recommended for safety.
Without proper protection, dust in quarries with a high silica or quartz content can sandblast the soft, thin surface of radiator fins.
Caustic and toxic
The range of environments considered caustic is considerable – fertilizer plants, many agricultural applications, salt stockpiles, chemical plants and composting operations are just a few.
Protecting the wiring and electrical systems is usually the biggest challenge in these conditions. “All you can do is slow the rate of corrosion,” Bell says. High quality, silicone-sealed electrical connectors help. Stainless steel is also used to resist corrosion in caustic environments, especially for bolts, connectors and brake lines.
Toxic environments may also be caustic, but the main goal in spec’ing a machine for a toxic environment is to protect the operator’s health. Haak cites a composting facility in Oregon where a loader operator contracted a long-term lung disease from breathing spore-laden dust. Such situations call for a cab air filtration package similar to those used on crop-spraying machines. This typically includes a cab with positive air pressure to keep dust out, charcoal canisters to eliminate fumes, a heavy-duty air filtration system that traps particles as small as 3 to 5 microns and internal air recirculation. Operator training is also critical. “We ask the operator to move 300 feet from the pile before opening the door and to dust his feet off before he gets in,” Haak says.
Likewise, worksites with high levels of noise may require operator training. Most modern wheel loaders have been engineered to operate at a relatively quiet 70 decibels or so. But in a rock quarry or other confined space with other machinery and radios operating, cumulative noise levels can escalate well beyond the 85 decibels at which the federal government mandates the use of hearing protection.
The rough and tumble world of loading logs in the woods may require shielding to protect the loader from external damage. But shielding is not without its tradeoffs. Shielding around the cab can restrict visibility. And belly guards or skid plates that protect the engine and transmission from damage from rocks and tree stumps also tend to collect oil and organic debris, which can present a fire hazard. Shielding for the cooling system is less problematic, but you’ll probably want to discuss all these options in detail with your equipment dealer.
Loaders working in log yards face a different challenge – primarily overloading. Log loaders do fewer cycles than bucket machines, Haak says, but the cycles include a much heavier lift. As a result the front tires become a critical factor because of the weight transfer when a load of logs is lifted. You may need to get a higher ply rating or carrying capacity than you would with a dirt machine or even a heavy-duty aftermarket rim to hold up under the weight.
Axles and suspensions also get a good workout in log yards, Bell adds. “Not only are they handling heavy loads but they are going at very high speeds. They’ll slam on the brakes and the front end goes down and the back end comes up, and then let off the brakes and the back end slams down.”
Extreme loads and duty cycles
To qualify as “severe” a wheel loader application does not have to be specialized or unusual. “If you are using a machine in a way that is different from what it was designed for then that may put that piece of equipment into the severe category,” Mucha says.
Over the past 10 years, Mucha says, loaders have become more specialized, which has cut down on some of this abuse. But as Bell notes, “Sometimes, for whatever reason, a customer will ask for a double-size bucket, or he doesn’t change buckets when dealing with wet or heavy material. The machine can suffer if it’s not setup for that.”
Shortened duty cycles may also put excessive stress on a machine, even if it’s only a matter of a few seconds. “A guy doing a 35- or 40-second duty cycle may have no brake cooling problem at all, but then you get an operator with a 25- or 30-second duty cycle and suddenly he’s got a cooling problem even though it’s a similar load or application,” says Haak. The solution here is easy – bigger or better brakes, or a separate brake cooling system, but discovering and spec’ing this before the machine is put to work is vital.
“One of the toughest conversations you hope you never have with a customer is when you tell them that some of their practices have shortened the life of their machines,” Haak says. “It’s much easier to front-load this process than to end load it.”