With an operating weight of 111,000 pounds, the MH3049 is the first of several wheeled material handlers that Caterpillar will introduce in the greater-than-25-tons class.
Coming immediately behind the MH3049 will be the MH3059 at an operating weight of 130,000 pounds. Cat stresses its material handlers are not modified excavators, but are purpose-built and designed specifically to work in industrial, scrap recycling, and waterway applications. A patented “ground entry and exit” with a step-in cab enhances safety for operators and service personnel.
Both units are powered by the Cat ACERT C9 8.8-liter engine featuring an electronically controlled, mechanically actuated, unit-injector fuel system that uses multiple-injection fuel delivery. The MH3049's C9 engine is rated at 300 horsepower while the MH3059 engine is rated at 325 horsepower.
Major structures use continuous welds that incorporate extensive chamfering and beveling to reduce stress concentration. Both the booms and sticks are constructed from single piece top and side steel plates eliminating the need for seams and internal baffles. The upper frame is designed specifically to dissipate loads transferred through the front linkage and counterweight, and the lower frame's unique tapered design evenly distributes loads and reduces stress. Oversized pins and bushings strengthen pivot points.
Using a closed-center, two-pump, load-sensing implement hydraulic system with electro-hydraulic pilot control, hydraulic pumps generate only as much oil flow and pressure as required for the application. To further enhance overall hydraulic power and efficiency, the machines regenerate boom-down oil flow, reducing the volume of oil the pumps must produce.
The machines divide hydraulic functions between the upper and lower main control valves, with the upper valve managing the boom, stick, work tools, cab riser, and cooling circuits, and the lower valve controlling travel, steering, and outriggers. This provides optimal flow management to allow multiple machine functions to occur at the same time without compromising performance, according to Cat. An independent closed loop swing system maintains swing priority at all time. The hydraulic-oil cooler, working with an auto-reversing fan, is positioned away from the independent engine cooling system to ensure optimum operating temperatures between 140 F and 160 F.
The hydraulic cab-riser system features the “ground entry and exit" with a step-in cab. Cab height on both machines is adjustable up to an eye level of 18.75 feet on the MH3049 and 23.5 feet on the MH3059. On the MH3049, raise time from ground level to maximum height is approximately 14 seconds; lowering time from maximum height to ground level is 12 seconds. Similarly, the raise time from ground level to maximum height on the MH3059 is approximately 17 seconds and lowering time from maximum height to ground level is 13 seconds. Adjustable sensors control the height of the cab above the ground. A manual safety override in the cab allows the operator to lower the riser in the event of engine power loss.
