January 1, 2013
Keeping safety first and productivity high is the ultimate goal of any maintenance program.
By Debbie McClung
Mines and quarries represent some of the most demanding conditions for wheel loaders. Ground-engaging tools, engines, cooling systems, and tires endure long hours in challenging terrain handling abrasive materials. Many work areas are congested with multiple machines that are loading material into trucks, crushers, and plant hoppers, as well as sorting and stockpiling — often moving finished materials from one end of a facility to another.
There can be little margin for error in these busy environments, and the last thing an operator needs to worry about is a machine that isn’t prepared to perform from the ground up. To safely and productively maneuver a wheel loader on these jobsites requires diligent attention to a manufacturer’s recommended maintenance program and manuals, and following additional guidelines established by the Mine Safety and Health Administration (MSHA).
“Routine daily maintenance and good pre- and post-use inspections on a wheel loader are critical to keeping safety first and productivity high,” says Chad Ellis, Doosan product manager.
Loading and unloading aggregate eight to 10 hours a day can create excessive wear on a machine’s ground-engaging tools. To ensure these high-impact tools stay in peak operating condition, fleet maintenance managers need to perform daily visual inspections of buckets with a keen eye to loose, cracked, or missing teeth and repairing or replacing compromised components as soon as possible.
A wheel loader’s attachments, such as buckets and pallet forks, are some of the most popular and hard-working tools in mining and quarry applications and deserve the same attention as the machine itself. Visual checks of these components should include hoses and tilt-and-lift cylinders to determine if wear is developing or damage has occurred.
There are other items on bigger buckets that have a working life as well. The operator should look at the condition of wear plates and bolted-on cutting edges, as well as attachment pins, to make certain they fit snug and properly.
Radial tires are commonly used on wheel loaders in mines and quarry operations for their durability and high bias properties that provide performance in all weather conditions. However, rough terrain can be extra punishing on tires over time if they have undetected leaks or are not properly inflated. Those responsible for equipment fleets should check their wheel loader’s maintenance manual for the proper psi and inflate the tires accordingly. “In addition to the correct pressure, routine maintenance and inspection of tires would not be complete without a thorough visual inspection to make sure no sizeable chunks of tread are missing and that the bead line and the rim are intact,” Ellis says.
One of the most important routine maintenance procedures required on a wheel loader is properly working brakes — at all times. Due to the nature of extracting an underground product, some mines and aggregate processing facilities have aggressive grades and often congested work spaces. For these reasons, operators must be able to stop their equipment and hold it with the machine’s parking brake whenever necessary.
MSHA Title 30 CFR 56.14101 states, “Self-propelled mobile equipment shall be equipped with a service brake system capable of stopping and holding the equipment with its typical load on the maximum grade it travels.” The federal regulation, available online at http://www.msha.gov/30cfr/56.14101.htm, also provides a table for evaluating the performance of service brakes.
Ellis states that wheel loaders may frequently travel through a wash pool typically found in larger concrete plants or quarries to remove slush or material buildup. “The driveline needs to be checked periodically to make sure there’s no leaking at the seals and that axles are protected. It’s better to take the time to catch a small failure before it becomes a catastrophic failure,” Ellis adds.
Fluids, oils, filters
According to Shane Reardon, Doosan wheel loader product specialist, fluids such as engine oil and coolants are key elements to engine compartment maintenance.
Reardon says equipment managers should complete fluid checks using dipsticks and sight glasses, and refer to their operator’s manual for instructions on filling their machine with the appropriate fluid in the correct increments at the recommended intervals. He also suggests that maintenance technicians resist the urge to use non-OEM specified filters. “It’s important to make sure you’re getting the best filtration properties and monitoring the same quality performance over the course of recommended maintenance intervals,” Reardon says.
The majority of new wheel loaders entering the market have been engineered with engine enhancements and/or after-treatment systems. They are designed to clean diesel engine exhaust and meet the EPA’s emission standards for interim Tier 4 (iT4) engines. While each equipment manufacturer has a slightly different emission strategy, it’s more important than ever to follow their guidelines for maintenance and service. Whether a manufacturer’s diesel after-treatment system is a cooled exhaust gas recirculation (CEGR) or the selective catalyst reduction (SCR) technology — or a combination of the two — these new technologies require advanced fluids to avoid costly repairs.
For instance, all machines using the CEGR with a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF) must use American Petroleum Institute (API)-rated CJ-4 oil (sometimes referred to as low-ash oil) to help reduce the amount of particulate matter in the DPF. Also, since sulfur is a significant contributor to diesel exhaust pollutants, the catalyst system used with iT4 engines is dependent on ultra-low sulfur diesel (ULSD). It has significantly less sulfur compared to prior diesel fuels (15 ppm versus 500 ppm).
Ellis points out that dust may be a maintenance factor in some smaller aggregate quarries. He recommends two additional preventive measures in these environments. Fleet maintenance managers should be sure to use an engine pre-cleaner to protect the engine cooling group. Many manufacturers have also incorporated variable-speed reversible fans to help clean the cooling system. “If you don’t use it (reversible fan) in dusty conditions, somebody in the maintenance department is going to be working on the cooling group more than they need to,” Ellis says.
Finally, no amount of recommendations will be successful if fleet managers, service technicians, or operators aren’t educated on current maintenance methods and procedures. Ellis says, if you’re going to do a majority of wheel loader maintenance yourself, you should at least obtain maintenance training and assistance from your equipment dealer on proper techniques.
The good health of a wheel loader from the ground up depends greatly on individuals dedicated to safety and productivity. Take advantage of your manufacturer’s recommendations, your dealer’s training, and other industry sources to maintain your machine’s optimum performance.
5 CHECKS FROM THE GROUND UP
1. Follow all guidelines in the manufacturer’s maintenance manual.
2. Ground level:
• Ground-engaging tools, attachment pins
• Lift arms
• Cylinders, hoses
• Undercarriage, axles
3. Engine compartment:
• Fluids, oils, filters, cooling system
• Advanced fluids (iT4 engines)
• Hoses, belts
4. Exterior cab:
• Entry/exit handholds
• Windshield, windows, wipers, washer level
5. Interior cab:
• Seat adjustments, seat belts
• Steering mechanisms
• Horn, rear-view camera, mirrors
• Gauges, indicators, switches, controls
• Cab air filter
Debbie McClung is a technical writer working for Doosan Infracore Construction Equipment.