Cat claims extra productivity, durability for giant excavator

Powering the 390D L is the 18,1-litre Cat C18 Acert diesel engine, Tier III compliant and rated at 523 net horsepower (390 kW). According to Caterpillar, the C18 features advanced electronic control, precise fuel delivery and refined air management for optimum performance, fuel efficiency and emissions control.

 

The company says that the torque characteristics of the engine allow full power at maximum rpm, resulting in efficient hydraulic-pump operation and positive hydraulic response. Refinements in the crankcase, cylinder heads and proprietary MEUI (Mechanical Electronic Unit Injector)fuel system provide enhanced performance and durability for the C18.

 

Design enhancements in the hydraulic system allow the 390D L to deliver significantly greater digging and lifting forces than its 385C predecessor, says Caterpillar. Main relief pressure in the implement circuits has been increased to 5,080 psi (35 000 kPa),up nearly 10 percent from that of the 385C.

 

This increase in operating pressure, combined with larger-diameter hydraulic cylinders, results in a nine percent boost in digging-arm and bucket breakout forces for the general-purpose and reach front-end configurations, and a seven percent increase for the mass excavation configuration.

 

Increased breakout force promotes faster trenching and loading cycles, plus stronger performance at the quarry face. In addition, lifting capacity over the end is increased by nine percent, and over-the-side capacity is up nearly 20 percent –the result of stronger hydraulics and a heavier counterweight. Also new in the implement hydraulic circuits are electrically controlled regeneration valves.

 

According to Caterpillar, an improved undercarriage for the 390D L features redesigned links that operate with lower stress, forged idlers for improved durability and heavy-duty track rollers and carrier rollers. In addition, the recoil spring has been lengthened, giving the recoil mechanism greater impact-absorbing capability to protect the undercarriage system from shock loads.

 

To accommodate the higher digging and lifting forces generated by the 390D L, the carbody (the structure mounting the machine upper to the track assemblies) is fabricated with thicker reinforcing plates at critical locations, says Cat. Complementing this change are thicker plates at the boom-foot mounting in the upper frame, as well as thicker reinforcing plates in the rails and bottom pan to accommodate the heavier counterweight and increased swing-torque.

 

Both the standard counterweight and the optional removable counterweight weigh 13.7 tons (12,4mt), making them slightly more than 6 percent heavier than the 385Ccounterweight. As a safety enhancement, activation of the optional counterweight-removal system locks out travel and implement-hydraulic functions to prevent unexpected movement of the machine. According to Caterpillar, booms and digging arms also are stronger, the result of thicker material used in their fabrication and an improved welding process.