Powering the new 390D L is the 18.1-litre Cat C18 ACERT, rated at 523 net horsepower (390kW). The C18 has electronic control, precise fuel delivery and refined air management. The engine's torque characteristics allow full power at maximum rpm, resulting in efficient hydraulic pump operation and positive hydraulic response, the manufacturer says. Refinements in the crankcase, cylinder heads and proprietary MEUI (Mechanical Electronic Unit Injector) fuel system provide enhanced performance and durability for the C18.
Main relief pressure in the new model's implement circuits has been increased to 35 000 kPa, up nearly 10% from that of the 385C. This increase in operating pressure results in 9% more digging force. In addition, with stronger hydraulics and a heavier counterweight, lifting capacity over the end is increased by 14% with over-the-side capacity up nearly 14%.
Also new in the 390D L's implement hydraulic circuits are electrically controlled regeneration valves, which improve responsiveness of the boom and digging arm cylinders and overall hydraulic efficiency. The resulting benefits include quicker cycle times and estimated fuel savings of more than 2%, Cat reckons.
A universal quick-coupler circuit, with offset lifting eye, is available for factory installation and is compatible with both dedicated and pin-grabber-type couplers.
The undercarriage for the 390D L has redesigned links that operate with lower stress. It also has forged idlers for improved durability and heavy-duty track rollers and carrier rollers. 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 is fabricated with thicker reinforcing plates at critical locations. There are also 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 counterweight, which at 12.4t is 6% heavier than on the predecessor model.
Booms and digging arms also are stronger, using thicker steel and an improved welding process.
Operator comfort and convenience
The 390D L's operator's station is spacious, quiet and comfortable with commanding visibility.
The cab is pressurized to keep out dust, and the filtered ventilation system combines with automatic climate control to maintain a constant, comfortable environment. The monitor provides full-color graphic displays with comprehensive machine information presented in either an English or ISO format.
The monitor provides fluid level checks when the engine is started, can list approaching service intervals and can display real-time fuel consumption information numerically. Flexible power modes—high power or economy—allow the operator to adjust machine performance to the task. Both modes provide the same digging forces, but the economy mode allows the machine to work with fuel-saving efficiency when production requirements are less critical.
The height of the control-lever consoles is adjustable, and the response and modulation of the electro-hydraulic joysticks can be adjusted through the monitor. The control-pattern changer, also accessible through the monitor, allows the operator to select preferred lever functions. In addition, the monitor displays images from the 390D L's optional rearview and Wide Area Vision System cameras, the latter mounted on the boom or side of the machine.
Halogen lights are standard, but can be replaced with optional high intensity gas lights on the boom and upper cab if more illumination is required. Cab lights are time delayed to give time to get out of the machine at night.
Service Improvements
The 390D L uses an electric fuel priming pump, which simplifies filter changes. A dual-element air cleaner with a double radial seal is standard. All filters, except for the high-pressure fuel filter, are accessible from the left side of the machine. Service safety features include a 24-volt service light receptacle and wider, 500-mm walkways that provide sure-footed access to maintenance points.
To make maintenance simpler, the 390D L has valve-controlled fluid-drain ports and self-contained hoses for fuel, coolant and lubricant systems. Easy-to-change spinon filters are used in the fuel and lubricant systems, and pressurised fluid sampling ports (in all pressurised fluid circuits) assure reliable fluid samples. An electronic warning system alerts the operator if the air filter or hydraulic filter is approaching restriction limits.
The Electronic Power Control (EPC) has been relocated from the cab (its position in the 385C) to the air cleaner compartment, allowing the cab floor to be washed without risk of damage to the EPC. For further reliability, the EPC and its electrical terminals are weather-proof.
390D L / 385C L Specification Comparison
| 385C L | 390D L | |
| Operating Weight | 84,980 kg | 88,180 kg |
| Engine Model | C18 ATAAC | C18 ATAAC |
| Power, Net | 523hp (390kW) | 523hp (390kW) |
| Main Relief | 32,000 kPa | 35,000 kPa |
| Travel Speed | 4.5 km/h | 4.5 km/h |
|
Max. lift capacity over end* |
24,820 kg | 28,250 kg |
|
Max. lift capacity over side* |
24,820 kg | 28,250 kg |
* At 6.1m radius, 6.1m depth, with 10m boom, 4.4m digging arm and 900-mm shoes
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