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HEX designed for productivity in severe applications

Whether working in excavating operations or using large hydraulic work tools ? eg hydraulic breaker ? the 349D L can perform reliably, while offering operator comfort and maintaining low operating costs.

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


The 349D L is designed with a powerful implement hydraulic system that generates a maximum flow of 734 litres per minute (l/min) and operates at a relief pressure of 35,000 kPa. The hydraulic system 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 control in all applications.

For optimum efficiency, 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 minimising the volume of oil exhausted to reservoir. The net results are faster cycle times and greater fuel efficiency.

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


Front linkage options allow the matching of machine capability to a range of applications. Boom construction features a large cross-section with internal baffle plates and 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 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 sealed with grease to decrease internal bushing wear, reduce travel noise and extend service life. An idler guard and bolt-on centre guard maintain track alignment when travelling 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 car body supports the track-roller frames, which incorporates press-formed pentagonal structures that are exceptionally strong. Robotic welding achieves three times the penetration of a normal weld, providing extremely durable structures.

Source: Caterpillar of Australia

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