The R 976-E electric crawler excavator, along with the R 980 SME-E, replace the ER 974 B for mine and quarry extraction.
The electric excavators are produced by Liebherr-France SAS in Colmar, France, and are not converted diesel machines. Both the excavators and their electric power system were designed and produced entirely by Liebherr.
They weigh 90 and 100 tons, respectively, and are available in backhoe and shovel versions. They stand out for their low noise level, optimum versatility, and zero CO2/greenhouse gas emissions during operation, the company says.
The electric system in the new Liebherr R 976-E 400 kW crawler excavator is supplied with 6000 V power via a cable connection, with the cable inlet in the center of the undercarriage, or on the sides if requested. A motor cable drum is also available as an option. The machine is powered by a high voltage 6000 V/50 Hz current collector. A switch cabinet transformer (high voltage/low voltage) and a low voltage cabinet for power distribution and control of 690 V, 230 V and 24 V networks are located on the upper carriage.
Thanks to its constant speed whatever the load, an excavator with an electric engine is expected to have a longer service life. Also, the high availability of transient power for complex machine movements enables very high productivity, according to Liebherr.
The R 976-E’s low-voltage electric squirrel-cage engine drives the hydraulic system. The engine features heat shielding on bearings and motor windings. Integrated into a frame with a reinforced flange, it enables safe, soft starting. The two robust electrical cabinets are assembled by welding into a structure specifically designed to withstand extreme working conditions. The lockable watertight (IP 65) doors are fitted with safety switches and an emergency stop. The high-voltage cabinet is a dedicated contact for power connection and voltage transformer, while the low-voltage cabinet is used for power connection monitoring.