July/August 1992
Following a regular maintenance and inspection routine makes smart business sense for wheel loader operators who want to protect their investment.
Wheel loaders can be critical players on many jobs in the scrap plant, and downtime can hurt as much as with heavier types of machinery. To keep wheel loaders running at peak efficiency, suggests Jerry L. King, product service manager at J.I. Case (Racine, Wis.), operators should adhere to a regular inspection and maintenance program that includes the following.
Fluid and Oil Levels. Checking fluid and oil levels is the most important element of a daily inspection, King says, noting that "any time you exceed the recommended intervals, you're just shortening the service life of the components that require fluid or oil to operate properly."
Levels are traditionally checked with a dipstick, but there is a trend toward sight glasses, which are said to make inspections easier and help avoid dust contamination. In any case, King recommends that inspectors refer to the manufacturer's operations manual for correct levels, and, when checking transmission fluid, pay particular attention to different level requirements for cold and warm fluid. Brake fluid, he says, should be checked before every shift, and hydraulic oil should be drained and replaced every 1,000 hours—sooner if the machine is operated in very dusty conditions. Hydraulic oil filters should be replaced and the suction screen should be cleaned at the same time.
In addition to checking the level of engine oil, inspectors should also check for the presence of burned oil, which usually means the engine is operating at higher temperatures than it should be—a condition that signals the need for an immediate inspection by a certified mechanic.
The engine oil also can reveal if diesel fuel is seeping into the crankcase, King points out. To check this, place a few drops of oil on a paper towel. The presence of a small amount of diesel fuel is normal and will make a light ring outside the oil blot. If the ring is excessive, however, it could indicate ring or valve wear.
Periodic oil analysis by a laboratory can offer a more thorough evaluation of engine wear. "Results may show that you need a different oil change interval," King says, noting that Case normally recommends that oil be changed after every 250 hours of use. "They can also forewarn you of wear by the presence of particles. And if you're aware of a problem, you can schedule downtime for repairs rather than face unexpected breakdown."
Turbocharged Engines. Engines with turbochargers should be idled for a few minutes before any engine shutdown. By cooling down the turbocharger, King explains, equipment life is extended.
Radiator. In most wheel loaders, radiator coolant bottles are conveniently visible, allowing for a quick, daily examination to determine whether it has been damaged during the previous day's operation.
Fuel Filters. Both primary and secondary fuel filters should be replaced every 500 hours—or sooner when working in extremely dusty conditions. In addition, King suggests that the fuel sediment bowl, which captures larger particles, be checked every 50 hours and cleaned if necessary.
Air Filters. Although some wheel loaders have a warning light in the operator compartment that indicates air filter restriction, many require periodic filter checks. With dual-stage cleaners, the primary filter can be removed and checked for tears, perforations, and excess dirt. If cleaning is necessary, King says, use compressed air (30 pounds per square inch maximum) and wash the element as directed in the operator's manual. The secondary filter should not be disturbed until replacement. (Case recommends that both primary and secondary filters be replaced at least once a year or after the primary filter has been cleaned three times.)
In addition to regularly cleaning and replacing air filters, wheel loader owners should consider equipping the machine with an air intake precleaner, which draws in outside air from just above the hood, causing a swirling action that filters out larger dirt particles before they can reach the air filter. The cost of a precleaner can be "quickly recovered" through filter element and labor cost savings, King reports.
The tank that collects moisture from most wheel loader air systems should be emptied at the end of each shift, minimizing the chances of moisture entering the entire system. Units equipped with air dryer systems require element replacement every 12 months.
Grease Points. Some wheel loaders have drive lines with "lubed for life" universal joints that do not require regular greasing. If the drive line is not sealed, however, this grease point should be lubricated according to the maintenance schedule. It's important to use the manufacturer-specified grease, King cautions, since "incorrect grease being extruded from the joint could open the seal to the joints, letting water and contaminants into the universal joints."
The center articulation and slip joints also should be checked and greased in intervals specified by the operator's manual. And while inspecting the center joint, check the hoses that route through to ensure they are clean, properly spaced, and not damaged.
Loader and Bucket. Pivot points on loader arms also need regular greasing with a proper lubricant, such as molydisulfide. At the time of lubrication, the inspector should look for damage to the cylinders and hydraulic plumbing.
When inspecting the bucket, King says, check its cutting edge for damage that might impair operation and examine the teeth to ensure wear limits have not been reached.
Tires. Because they are reliable and long lasting, tires are often neglected in routine inspections. Nevertheless, regularly checking them for wear, punctures, or cuts is an easy way to avoid blowouts during operation. A daily tire inspection is also an opportune time to clear away debris that may have collected on top of the axles during the previous shift, King points out.
Check the tightness on all lug nuts after 20 hours of operation of new tires or wheels that have been removed, and follow up the inspection every month or 250 hours afterward.
Inside the Cab. Loose dirt or mud built up around controllers and switches can damage these components, and a buildup of debris on the floor can impair pedal operation—especially if the brake pedals are floor mounted. Therefore, King recommends that any dirt or mud inside the cab be brushed away daily.
The cab inspection should also include a check of the windshield wiper and fluid level while the unit is running.
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Although the number of elements to check may make an inspection and maintenance program seem time consuming, King emphasizes that "it truly does become a routine that can be completed in just a few minutes." Furthermore, he says, "I can't emphasize enough how adhering to maintenance schedules can save hours and even days of expensive downtime." •
Following a regular maintenance and inspection routine makes smart business sense for wheel loader operators who want to protect their investment.