Supply Lines
September 2007
The New Generation of Production Wheel Loaders
Tier 3 engine requirements and a hot quarry market have stimulated growth in the mid-sized wheel loader category.
Wheel loader application tips and benchmarks for quarry loading
Based on studies at mines and in testing at the company’s proving grounds, Peoria, Ill.-based Caterpillar has developed recommendations for wheel loader applications and operating techniques and also has determined benchmarks to use as an aid in assessing wheel loader performance. Of course, the mine design and conditions play an important role in wheel loader productivity. Favorable site conditions and mine design include the following:
-
Level, dry, smooth, firm floors;
-
Sufficient cross fall and drainage in high rainfall areas to minimize tire damage;
-
Well-fragmented materials that minimize crowding time, particularly in the toe area of the cut;
-
Lower face profile — optimum bench height is the bucket hinge pin height at maximum lift; and
-
Multi-face loading — due to excellent mobility, wheel loaders are the only loading machine that can efficiently perform such duties.
When selecting a loader/truck fleet, keep in mind that the most efficient pass match for wheel loaders is four to six passes. Efficient operations should achieve a 90 to 110 percent bucket fill factor with wheel loaders. Conditions should allow cycle times of 32 to 42 seconds. Average cycle time observed in efficient operations is 38 seconds.
Conditions that are particularly negative for wheel loaders include poor or very wet underfoot conditions and tight loading areas. It’s also important that the loader operator keep the pit floor free of rocks to minimize tire damage to both the loader and the trucks.
Proper wheel loader operating techniques are critical to productivity as well as machine maintenance costs. The following operating techniques are recommended:
-
Use truck exchange time to make the first pass a good pass by filling the bucket completely — ensure that the truck is correctly spotted by loader positioning or sounding the horn;
-
Enter the pile straight on, with the floor of the bucket parallel to the pit floor;
-
Keep the frame straight when digging;
-
Lift the bucket before crowding;
-
Fill the bucket by the time the lift arms are horizontal;
-
Keep the time in the face below 12 seconds;
-
Minimize non-productive floor contact with the bucket; and
-
Maintain proper kick-out adjustment.
Selecting and using appropriate ground-engaging tools (bucket edges and teeth) also is important to loader productivity and maintenance. Never operate with a bare edge. — by Mark Sprouls, Caterpillar News Service
Volvo
Improved fuel efficiency
Volvo Construction Equipment’s new L350F model
wheel loader offers improvements on nearly all aspects of its
predecessor, the L3330E model wheel loader. The flagship machine —
introduced at Bauma 2007 — features much higher productivity than the
outgoing L330E, ultimately resulting in much-improved fuel efficiency,
according to Volvo. The improvements, the company says, are a
combination of the L350F’s new Tier 3/Stage III Volvo engine, stronger
hydraulics, and a new transmission with lock-up and new axles.
The new model also is fitted with a larger cab, which features a larger, air-conditioned interior that is insulated from noise, dust, and vibration — the latter thanks to viscous cab mounts and air suspended seat. The cab also meets ISO requirements.
Caterpillar
Two new production loaders coming
Caterpillar has announced that it is replacing
its 800-horsepower, 209,000-pound 992G wheel loader with two K-series
models. The 992K, specifically designed for quarry work, and the all new
993K, designed for other mining applications, were announced last spring
at Europe’s BAUMA trade show.
The new 992K is very similar in dimensions to the 16- to 17-cubic yard 992G model it replaces except that it is heavier (214,000 pounds). Its rated payload is 17 percent less than the G, but its cycle times are faster. The company says it has been designed to load a Cat 777 off-highway truck in five passes. New features include a durable fabricated boom design featuring castings for the linkage and bucket pin connection members, a positive flow control implement hydraulic system, and serviceability improvements.
Cat says the 993K is a completely new machine, both in terms of its size class and its platform. The 950-horsepower machine weighs 278,750 pounds and has a 25-ton payload rating. Designed for hard bank engagement, the 993K features Z-bar linkage and its hydraulics and power train have been optimized for higher penetration, greater rimpull, and higher breakout forces. Cat says the machine is 10 percent more productive than the 992G and matches perfectly with the Cat 777 and 785 off-highway trucks.
John Deere
New 7-yard loader entry
John Deere entered the 7-yard-loader class in
2005 with the 844J. Designed and manufactured by Deere, the machine
features a 12.5-liter, 380-horsepower (net) engine with wet sleeve
cylinder liners for enhanced cooling. The company claims the 844J has
best-in-class cooling and maintenance access to cooling apparatus. The
69,300-pound machine also features a smooth-shifting proprietary
transmission, a ride control system, excavator-style hydraulics, and an
optional joystick steering control system.
Komatsu
More power and efficiency
Komatsu implemented a series of improvements in
its 7-cubic-yard WA500 loader when it introduced the dash-6 version of
the machine last year. Changes include a Tier 3, 332-horsepower engine,
operating weights of 71,585 to 74,010 pounds, depending on trim, and a
number of upgraded components. Key among the latter is a new, large
capacity torque converter that improves the machine’s truck-loading and
hill-climbing performance, and variable piston pumps which, combined
with Komatsu’s load-sensing system, reduce the wasted flow of hydraulic
oil and increase rim pull for better bucket penetration and reduced
cycle times.
The WA500-6 has two operating modes — economy and production — and has an optional lock-up transmission to improve production efficiency in load-and-carry or hill-climbing applications.
Doosan Infracore
New generation 6-yard loader
Doosan Infracore replaced its Mega 500 wheel
loader late last year with the new DL500, a 6.3-cubic-yard model with a
335-horsepower engine and Power Shift transmission. The new model has
more power and a larger cab than its predecessor, according to the
company, and improvements to the power train are said to have increased
fuel efficiency. In addition to new comfort features, such as a
multi-adjustable air-suspension seat, the DL500 has larger front pins
and all grease points for pins and bushings are accessible from the
ground.
Case Construction Equipment
More power, comfort, efficiency
Case Construction Equipment has introduced the
E-series version of its 921 wheel loader, adding a Tier 3 engine,
improved operator comfort and visibility, and easier maintenance. The
new engine develops 297 net horsepower in the 921E’s high-production
mode and standard bucket size has been upgraded to 5.75 cubic yards. The
machine also has an “economy” work mode to maximize fuel efficiency in
light duty work, and an “auto” work mode in which the machine’s control
system adjusts power curves to move the maximum amount of material per
pound of fuel, according to Case. The machine’s expanded cab is quieter
and visibility has been increased.
Liebherr
New series 5- and 6-yard loaders
Liebherr calls its new L 566 and L 580 its
“Generation 6” wheel loaders. The 259-horsepower L 566 weighs 50,570
pounds; it has a 5.25-cubic-yard standard bucket capacity and a tipping
load of 24,750 pounds. The 272-horsepower L 580 weighs 54,185 pounds; it
has a 6.5-cubic-yard standard bucket and a tipping load rating of 39,850
pounds. Both feature Tier 3 engines with more power than the models they
replace. Their cabs are 28 percent larger than the previous models and
feature single-part laminated front windscreens.
Dressta
‘Extra’ version debuts
Dressta says it has enhanced the top end of its
wheel loader line with its 560E Extra model which features a new Tier 3
turbocharged 427-horsepower engine, joystick boom and bucket controls,
hydrostatic steering, and a high-visibility cab. The 7-cubic-yard
machine has a three-speed, full powershift, countershaft transmission
and a 92,549-pound operating weight. It uses Z-bar linkage for maximum
breakout force, and a single bucket cylinder to reduce weight in front
of the machine and enhance payload capacity. Oil change intervals have
been increased to 500 hours.
Rockland
Stronger buckets, less weight
Rockland says it constructs its HD-S Straight
Edge and HD-V Spade Nose rock buckets with high-strength, weight-saving
alloy steel throughout to achieve added strength without added weight.
Designed specifically for handling rock, the buckets feature a
sloped-bottom design that is said to minimize bottom and corner wear.
Bracket foundations run from the loader brackets to the cutting edge to
increase bottom strength, and replaceable skid shoes keep the bottom of
the bucket off the quarry floor. The HD-V Spade Nose model is designed
for better penetration and breakout of hard, stony material or blasted
rock, while the HD-S Straight Edge is designed to remove loose and
broken material easily and provide better dump height and retention.
