The Liebherr R 976-E and R 980 SME-E electric crawler excavators replaces the previous ER 974 B, designed for mine and quarry extraction work.
The new models are not just converted diesel machines, though. The excavators and their electric power system are designed and produced entirely by Liebherr-France in Colmar.
The electric system in the new Liebherr R 976-E 400 kW crawler excavator is supplied with 6000 V power via a plug-in cable connection, with the cable inlet in the centre 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 6000V/50 Hz current collector. There is 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 on the upper carriage. The low-voltage electric squirrel-cage engine drives the hydraulic system.
Liebherr says that the plug-on excavators are cheaper to run and maintain than a conventional diesel machine as well as being cleaner and quieter.