An excavator comprising: an electric motor having a commercial power supply and a battery as the drive power sources therefor; and a hydraulic actuator having a hydraulic pump driven by the electric motor, as the hydraulic source therefor. The excavator has: a first power supply mode in which the electric motor is driven while the battery is being charged by the commercial power supply; and a second power supply mode in which the electric motor is driven only by the battery. A power supply cable for supplying power from the commercial power supply is connected to a power supply port and, if the electric motor has stopped operating, the excavator moves from the second power supply mode to the first power supply mode.

A working machine includes an auxiliary system carried by the working machine, one or more batteries and an onboard thermal transfer system. The one or more batteries power an electrical system of the working machine. The onboard thermal transfer system utilizes a coolant configured to remove at least a portion of heat generated by the one or more batteries during charging or discharging of the one or more batteries and using the coolant heated by the thermal transfer system to heat the auxiliary system.

A mobile mining machine includes a plurality of traction elements, a plurality of motors, a power source in electrical communication with the plurality of motors, and an energy storage system in electrical communication with the plurality of motors and the power source. Each of the motors is coupled to an associated one of the plurality of traction elements. Each of the motors is driven by the associated traction element in a first mode, and drives the associated traction element in a second mode. The energy storage system includes a shaft, a rotor secured to the shaft, a stator extending around the rotor, and a flywheel coupled to the shaft for rotation therewith. In the first mode, rotation of the motors causes rotation of the flywheel to store kinetic energy. In the second mode, rotation of the rotor and the flywheel discharges kinetic energy to drive the motors.

Hybrid construction machinery has a power storage apparatus that can be warmed up quickly and has a lengthened life. The machinery includes an electric motor assisting a prime mover in power and generating electric power. The power storage apparatus transfers electric power to and from the electric motor. A warm-up circuit circulates a warming medium in the vicinity of the power storage apparatus, and a control device controls circulation of the warming medium. On-board equipment state detection units detect on-board equipment states to estimate an output request for the power storage apparatus from the on-board equipment. Circulation of the warming medium is controlled based on a temperature of the power storage apparatus and a determination temperature for determining whether to circulate the warming medium in the warm-up circuit. The control device further varies the determination temperature according to a result of detection by the on-board equipment state detection units.

A drive control system includes an electric motor, a capacitor, a revolution sensor, a driving device, and a control device. The driving device causes the capacitor to supply electric power to the electric motor to operate the electric motor and causes the capacitor to store the electric power, generated by the electric motor, to brake a turning body. The driving device configured as above is driven by driving electric power supplied from the capacitor. When a charging stop condition is satisfied, the control device stops the driving electric power supplied from the capacitor to the driving device. The charging stop condition is a condition that a turning speed detected by the revolution sensor is a predetermined speed or less while the turning body is decelerating.

A portable power supply system supplies a remotely controlled, electrically driven work machine with electrical power. The work machine includes continuous tracks and is equipped with a maneuverable arm that carries a tool at its free end. An electric motor is connected to a hydraulic pump and supplies the machine with a hydraulic medium. The work machine is connected under normal operation to a primary source of power via an electrical cable. The primary source of power includes a fixed alternating current electricity distribution grid at the location. In order to be able to supply the current that is required it includes a DC energy-storage arrangement that, including a secondary source of power, can store energy and, when necessary, supply energy in electrical form. A coupling arrangement makes it possible to choose between connecting the motor to the primary or the secondary source of power.

A method for operating a drive system for a work machine is described. A first electric motor is associated with a travel drive of the drive system and a second electric motor is associated with a work drive of the drive system. An electric energy store for operating the first and the second electric motors is associated with the travel drive and the work drive. The method includes operating the first electric motor in generator mode to produce braking power of the travel drive, electric power being produced in the generator mode. The method further includes supplying, completely or partly to the energy store and/or to the second electric motor depending on a state of the energy store, the electric power.

In an electric drive system in which a battery is not connected to a DC bus, even when a load on a traveling electric motor increases suddenly, it is made possible to avoid such a situation that the DC bus voltage drops to a level equal to or lower than an operating voltage of an inverter and the inverter stops working. To this end, a DC bus voltage drop prevention device controls such that, when the voltage of the DC bus drops below a first threshold value, the output torque of the traveling electric motor is decreased according to an amount of decrease in the voltage of the DC bus, and when the voltage of the DC bus drops below a second threshold voltage lower than the first threshold voltage, the output torque of the traveling electric motor is decreased to zero or a value within a range of magnitude with which a work vehicle stays stationary on a level ground.

The disclosure relates to a work machine, comprising a primary energy source for feeding electric energy into a link, a gear for performing a task of the work machine, at least one electric drive connected to the link in order to operate the gear of the work machine, a holding brake for fixing or releasing the gear, and an energy store which is connected to the link in order to provide electric energy demanded from the link upon actuation of a gear and/or to absorb electric energy fed into the link. According to the disclosure, during an emergency lowering of the gear, the at least one electric drive to convert the kinetic energy into electric energy and to feed it into the link. In the event of an unavailability or failure, the primary energy source is configured to absorb the energy fed into the link by the electric drive.

A shovel includes a lower traveling body, an upper turning body turnably mounted on the lower traveling body, a hydraulic actuator that drives driven parts including the lower traveling body and the upper turning body, a main pump that supplies hydraulic oil to the hydraulic actuators, a pump motor that drives the main pump, and a power storage device that supplies electric power to the pump motor. When the charging cable is connected to the charging port during the operation of the shovel, the shovel causes the hydraulic actuators to shift to the inoperable state. When the charging cable is connected to the charging port, the shovel does not start the pump motor even if an input for starting the pump motor is received from a user.