Load And Carry
- Published: Thursday, 01 February 2007 07:00
Recent wheel loader product introductions generally have been focused on the mid-range class of machines. Manufacturers have upgraded their older models with new engines, improved hydraulic and cooling systems, and more sophisticated machine-health monitoring systems.
The largest among the new loaders is Caterpillar's 990H. It replaces the 990G Series II but retains certain features of the older model including the impeller clutch torque converter, Rimpull Control System, and STIC controls. According to the company, the 990H can load 60- to 70-ton-capacity trucks in standard-lift configuration and 100-ton trucks in the high-lift version. Rated payload for the standard lift is 16.5 tons and operating weight is 171,642 pounds. Bucket capacities range from 11 to 12 cubic yards.
The loader is powered by Cat's C27 ACERT engine, rated at 627 horsepower. The V-12 C27, displacing 1,648 cubic inches, offers 500-hour oil-change intervals and meets both U.S. Environmental Protection Agency Tier-3 and E.U. Stage-IIIa standards. The loader is equipped with an air-to-air aftercooling system to reduce the temperature of air entering the engine intake. This results in lower emissions and steadier performance at high altitudes and in high ambient temperatures.
The 990H's cooling system design isolates the radiator and the hydraulically driven, variable-speed cooling fan from the engine compartment, allowing the radiator to receive ambient air from outside rather than receiving heated air from the engine compartment. Cat says the loader's new modular radiator improves serviceability and increases cooling efficiency by 22%. It routes coolant through the radiator twice and has a modular core that allows removal of a single module without removing the entire radiator.
Hyundai Construction Equipment plans to unveil its 7A generation of wheel loaders at Bauma 2007, featuring a wide range of detail improvements.
The new generation of Hyundai loaders will be fitted with Tier 3-compliant engines and will feature common-rail injection technology. Inside the cab, the main control lever has been redesigned and extra functions added. For example, an operator can now switch between forward and reverse by pushing a button. Another button activates the kick-down switch, which releases extra power when traveling. The loaders' new light automatic mode cuts gear changing times by 20%, according to the company.
The loaders also are equipped with a new graphic display featuring a user-defined menu in the display panel, making it easier to read. Additional warning lights notify the driver in the event of a fault. As an option, the image from an outside camera also can be shown in the display. More comfortable seats, a heated outside mirror and improved storage options make the wheel loader safer and more pleasant to operate.
Chromium-plated bolts at all key linkage points also increase reliability and together with extended maintenance intervals improve the overall economy of the machine. Another new feature is a reversible cooling fan; running clockwise in normal cooling mode, the fan can be switched to run anti-clockwise for maintenance purposes. This draws dirt out of the ventilating slots and cleans the cooler to maintain cooling efficiency.
Komatsu recently introduced several new loader models, the largest of which is the 118,385-pound WA600-6. Powered by a Komatsu SAA6D170E-5 six-cylinder diesel rated at 502 horsepower at 1,800 rpm, it is the first of Komatsu's wheel loaders to feature a Tier 3-compliant engine. Breakout force is 87,230 pound-feet and straight static tipping load is 80,645 pounds. The standard 8.4-cubic-yard bucket is suited for loading 50- to 65-ton haul trucks. The WA600-6 offers adjustable travel speed and traction control settings for multiple applications. A hydraulically driven, reversible cooling fan uses only the power required to provide necessary cooling for a particular application.
Komatsu claims the loader's hydraulic cycle times with a rated load in the bucket are exceptionally quick ó taking only 9.3 seconds to raise a loaded bucket, 2.3 seconds to dump it, and 4.1 seconds to lower an empty bucket.
In addition, Komatsu added the 272-horsepower WA450-6 and the 299-horsepower WA480-6 loaders to its line. The WA450-6 has operating weights of 48,920 to 49,430 pounds and a dumping clearance of 10 feet 3 inches when equipped with a 5.5-cubic-yard general-purpose bucket. The WA480-6 has operating weights of 54,200 to 54,830 pounds and a dumping clearance of 10 feet 6 inches when equipped with a 6-cubic-yard general-purpose bucket. Both machines are powered by a Komatsu SAA6D125E-5, Tier 3-certified diesel engine with electronic, common rail fuel injection system and feature a large-capacity torque converter and closed-center load-sensing system.
The loaders' automatic transmission selects the proper gear speed based on conditions such as travel and engine speed, and has a kick-down switch that automatically downshifts from second to first when beginning the digging cycle; in reverse, it automatically up-shifts from first to second. A hold switch locks the transmission to either the third of fourth gear speed when auto shift is selected. The machines, equipped with Komatsu's vehicle health monitoring system, feature an in-cab monitor that keeps the operator informed of all machine functions, including fluid and filter change intervals and troubleshooting memory display functions. In addition, the system can send operating information to a PC or secure Web site using wireless technology.
Terex Construction has three new units in its TXL series: the 68,000-pound TXL 500-2, the 50,000-pound TXL 400-2, and 48,500-pound TXL300-2. The TXL 500-2 is fitted with Cummins' six-cylinder QSM11 engine rated at 335 gross horsepower at 1,900 rpm. The TXL 400-2 has a QSL9 six-cylinder engine rated at 280 gross horsepower at 2,000 rpm. The TXL 300-2 features a Doosan six-cylinder diesel engine rated at 217 gross horsepower at 2,000 rpm. All three have full power shift transmissions offering four forward gears and two reverse gears.
Breakout force reported for these models ranges from just over 61,000 pound-feet on the 500-2 (with 6.3-cubic-yard bucket) to 36,400 pound-feet on the 300-2 (with 3.9-cubic-yard bucket). Maximum dump height is 11 feet for the 500-2, 10 feet 2 inches for 400-2, and 9 feet 6 inches for the 300-2.
At last year's Intermat trade show, Hitachi Construction Machinery introduced the ZW220, ZW250 and ZW310, all of which offer a number of features for improved performance and reliability. The flagship 52,000-pound ZW310 is powered by a 295-horsepower Daimler Chrysler OM460LA six-cylinder, turbocharged and intercooled diesel that complies with both Tier 3 and E.U. Stage IIIa emissions standards.
All three models provide three working modes for differing job needs and operator preferences, including P mode for heavy-duty excavation to L mode for light-duty excavation. In each working mode, the machine's total torque system controls engine and pump parameters to provide penetration force and implement speed in accordance with job needs. In addition, three travel modes are available, and shift timing can be electronically controlled in response to travel speed and load conditions, rather than travel speed only. Clutch cutoff timing can be selected from three positions to suit various job conditions. The series also features a torque proportional differential as standard equipment, allowing the loader to adjust force to each drive wheel to prevent slipping and gain maximum traction in rough or wet terrain.
A new hydraulic system allows the ZW loaders to lift the bucket 10% faster while traveling, and parallel/tandem circuits enable both the lift arm and bucket to be operated simultaneously. When carrying a load, a float system allows the lift arm to accommodate terrain irregularities by using its own weight rather than by assistance from the hydraulic system. A standard leveling system enables the bucket to be set parallel to the ground after rollout, allowing potentially quicker cycle times.
ZW loaders feature a hydraulic oil-replacement interval of 4,000 hours plus 500-hour filter replacement intervals. Special bushings, impregnated with high-viscosity oil, are fitted at vital joints to reduce grease consumption, extending lubrication intervals up to 500 hours ó five times longer than with previous models.
Case Construction Equipment upgraded the 50,000-pound 921E wheel loader, with an electronically controlled engine that provides increased efficiency, a new cab that offers greater operator comfort and visibility, and easier maintenance. The new Case wheel loader also delivers a larger payload of 5.75 cubic yards.
The 921E is powered by a fully electronic Tier 3-certified engine that incorporates common-rail fuel-injection and multiple-idle settings to reduce fuel consumption. Operators can choose from three power curves and four work modes. In maximum performance power mode, the six-cylinder engine on the 921E produces 297 horsepower.
The 921E shares the same recently redesigned cab as the 721E and 821E, and offers the same operating interface. The standard single-lever joystick loader control with forward-neutral-reverse quick shuttle switch and transmission downshift button puts all the controls at the operator's fingertips. A digital display records real-time data, shows diagnostic information and allows programming the operational modes.
Case also redesigned the bucket on the 921E for higher productivity and increased life, extending the bolt-on cutting edge to accommodate larger loads and creating a fine edge for easier penetration into the pile. The skid plates on the 921E are bolted on for easier repair and replacement. The bottom floor plate on the bucket is set at a 5-degree angle, and the hinge pins are raised up out of the dirt and debris for longer life and improved mixing and filling of material.
Optional ride control provides improved material retention while reducing shocks on the machine and operator fatigue. Ride control can be set for full-time mode or in auto mode, which kicks in when road-traveling faster than 3 mph.
To learn more about these products and companies, complete the reader service card on page 47 and mail it to Rock Products or visit www.freeproductinfo.net/RP
|Operating Weight (lb)||Engine Power (hp)||Bucket Capacity (cu yd)|
|TXL 500-2||68,000||335||5.9 - 6.8|
|TXL 400-2||50,000||280||4.8 - 6.1|
|TXL 300-2||48,500||217||3.5 - 4.6|
|ZW310||52,000||295||4.2 - 5.9|
|ZW250||44,700||240||3.7 - 5|
|ZW220||39,500||220||3.1 - 4.6|