HYBRID CONSTRUCTION MACHINERY AND AUXILIARY CONTROL DEVICE USED THEREIN

Disclosed is a hybrid construction machine that includes a control device 80 and an auxiliary control device 88. The control device 80 switches between a hydraulic/electric complex swing mode in which, when the swing control lever device 72 is manipulated, both the electric motor 25 and the hydraulic motor 27 are driven to drive the swing structure 20 by using the sum of the torque of the electric motor 25 and the torque of the hydraulic motor 27 and a hydraulic-only swing mode in which, when the swing control lever device 72 is manipulated, only the hydraulic motor 27 is driven to drive the swing structure 20 by using only the torque of the hydraulic motor 27. The auxiliary control device 88 includes a monitoring controller that is connected to the control device 80 and to the electric motor 25 to monitor the temperature or electrical leakage in the electric motor 25 as a substitute controller for the power control unit 55 or the electrical storage device 24 when the power control unit 55 or the electrical storage device 24 is removed due to its fault.