by Kyle Molyneux | Fri 23 Apr 2021
Electric Liebherr excavators
The R 976-E electric crawler excavator, along with the R 980 SME-E, replaces the ER 974 B for mine and quarry extraction. Weighing 90 and 100 tonnes respectively, the excavators and their electric power system were designed from the ground up and produced entirely by Liebherr.
The electric system in the new Liebherr R 976-E 400 kW crawler excavator is supplied with 6,000V power via a 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 high voltage 6000V/50Hz current collector. A switch cabinet transformer (high voltage/low voltage) and a low voltage cabinet for power distribution and control of 690V, 230V and 24V networks are located on the upper carriage.
The technology used in the R 976-E and R 980 SME-E offers a host of advantages. Thanks to its constant speed whatever the load, an excavator with an electric engine has a longer service life, reckons Liebherr. Also, the high availability of transient power for complex machine movements enables very high productivity. 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 (IP65) 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.
The R 976-E and R 980 SME-E are said to be extremely quiet, and feature spacious cabs equipped with an automatic air-conditioning and heating system, while the exterior has a 270-degree camera system plus an armoured windscreen and roof window. The operator’s platform features a large number of additional monitoring functions and a standard 9in screen.
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