China Construction Machinery Business Online
Cat 349D L hydraulic excavator
Post Date: 2011-04-22

The new Cat 349D L hydraulic excavator, with an operating weight from 44.8 tons to 51.1 tons depending on machine configuration, is designed to work productively across a broad range of applications. Whether working in sustained excavating operations or using large hydraulic work tools—such as a shear, hydraulic breaker or multi-processor—the 349D L's durable design allows it to perform reliably, while offering exceptional operator comfort and maintaining low operating costs. A powerful hydraulic system, driven by the fuel-efficient Cat C13 diesel engine, combined with durable structures, a choice of heavy-duty undercarriages and front linkages to tailor the 349D L to the most demanding jobs.

The Cat C13 engine, with ACERT technology, gives the 349D L a net power rating of 283 kW. The C13 integrates an innovative intake-air-management system with an electronically controlled, mechanically actuated, unit-fuel-injection system (MEUI) that yields steady power in all operating situations and exceptional fuel efficiency.

The 349D L is designed with an extremely powerful implement-hydraulic system that generates a maximum flow of 734 L/min and operates at a relief pressure of 35 000 kPa. The hydraulic system automatically gives priority to boom-up and swing functions, eliminating the need for operator-selected work modes and increasing cycle times. Operation of the pilot-actuated main control valve is proportional to lever movement, assuring precise response and excellent controllability in all applications.

For optimum efficiency, the design of the hydraulic system locates major components—main pumps, control valve and hydraulic tank—closely together, allowing the use of shorter hydraulic lines for reduced frictional losses and minimal pressure variations. Regeneration valves in the digging-arm and boom circuits transfer oil between cylinder ends, reducing unneeded hydraulic flow by minimizing the volume of oil exhausted to reservoir. The net results are faster cycle times and greater fuel efficiency, which translate into increased productivity and reduced operating costs.

A choice of hydraulic circuits provides exceptional versatility and that allows one-way, two-way or combined hydraulic flows to efficiently operate a range of heavy-duty hydro-mechanical work tools. This system allows the 349D L to work productively in applications such as demolition, scrap processing and breaking road surfaces and bedrock. For attaching work tools, Caterpillar offers both a dedicated coupler and the Cat Center-Lock Pin Grabber Coupler, which features a positive, patent-pending locking system.

A choice of front linkage options allows the matching of machine capability to a wide range of application. Boom construction features a large cross-section with internal baffle plates and the use of forged steel in critical high-load areas, such as the boom-foot and boom-cylinder connections. The stick is made of high-tensile-strength steel and features a large box-section design that integrates interior baffle plates and a heavy bottom wear plate for durability.

The 349D L is available with a fixed-gauge undercarriage. Track links are designed to reduce stress concentration and are sealed with grease to decrease internal bushing wear, reduce travel noise and extend service life. An idler guard and bolt-on center guard help maintain track alignment when traveling or working on slopes. Three-stage planetary final drives assure positive power to the tracks, and a straight-line travel circuit keeps track speed consistent if the front linkage is operated.

The heavy-duty main frame is designed and fabricated for maximum durability, with box- section main channels connected by a large-diameter tube at the boom foot to add rigidity and strength. A durable carbody supports the track-roller frames, which incorporates press-formed pentagonal structures that are exceptionally strong. Robotic welding achieves 3 times the penetration of a normal weld providing extremely durable structures.

The 349D L is equipped with certified-ROPS cabs that comply with ISO standard 12117-2:2008. The new ROPS-cab design features a larger, more comfortable environment with enhanced visibility, lower operator sound levels and improved serviceability.

Glass area in the new cabs is increased 12 percent, compared with the previous design, interior volume is larger by 3 percent with improved pressurization. The use of viscous rubber mounts dampens vibration to ensure optimal operator comfort. In order to accommodate the new ROPS-cab design, mainframes have also been redesigned.

The ROPS-cab design allows the Falling Object Guard System (FOGS, ISO10262) to be bolted directly to the cab to meet job site specifications. The cabs feature pilot-operated, joysticks for all implement and swing functions, which provide smooth precise operation.

Pilot operated control levers reduce operator effort, and a choice of joystick or foot pedals options modulate the operation of hydro-mechanical tools. For operator convenience and machine protection, the 349D L's instrumentation, prior to start up, checks engine-oil, hydraulic-oil and engine-coolant fluid levels, and then advises the operator in one of 27 different languages.

To further lower operating costs, the 349D L features extended fluid-service intervals, centrally located service points to facilitate ground-level maintenance and a readily accessible greasing block on the boom for lubricating hard-to-reach locations. S.O.SSM fluid sampling ports for the engine and hydraulic system enables faster effective samples to be taken ensuring long life and reliability. A pilot-system filter, in-tank hydraulic-oil cartridge filters, radial-seal air cleaner (with efficient pre-cleaner) and a fuel/water separator integral with the primary fuel filter assist in keeping the 349D L running reliably to protect the customer's investment.

The 349D L also is equipped with the Cat PL321 Product Link system that uses Cat Asset Watch software to provide time-based fencing (determining when the machine can operate) and reporting of machine hours and location. Adding Health Watch and Maintenance Watch software expands system capability to include codes from onboard sensors, fuel data and maintenance-related reporting. The Product Link system adds customer value by providing a machine/fleet-management tool that enhances return on investment.

Source: Construction & Maintenance

Key Words: Cat 349D L | hydraulic excavator
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