Patent ID: 8366374

Claim:
A dual arm working machine including a lower travel structure having a travel device, an upper swing structure that is provided above the lower travel structure and has a cab, two front work devices that are provided swingably in top-bottom and left-right directions of the dual arm working machine, and are located on the right and left sides of a front portion of the upper swing structure, and have arms, booms and working devices, respectively, and operating devices that are provided in the cab and instruct the two front work devices to operate, the dual arm working machine comprising: arm angle detectors that detect angles of the arms relative to the booms, respectively; control part displacement detectors that detect operating directions of the operating devices and the amounts of operations of the operating devices; and an operating range calculator that calculates drive signals for the arms based on detection signals received from the arm angle detectors and on detection signals received from the control part displacement detectors, wherein, when a value used to evaluate and determine stability of the dual arm working machine is defined as a stability determination value, the stability changing depending on the positions of the front work devices, and when a range of the stability determination value, in which the dual arm working machine does not become an unstable state regardless of the states of the operations of the two front work devices, is defined as a normal range, a range of the stability determination value, which is present on an outer side of the normal range and adjacent to the normal range, is defined as a stable state limit range, a range of the stability determination value, which is present on an outer side of the stable state limit range and adjacent to the stable state limit range and in which the stability determination value is larger than a predetermined stability determination standard value, is defined as an unstable range, the operating range calculator calculates the stability determination value based on the arm angles detected by the arm angle detectors of the two front work devices; and when the stability determination value is in the stable state limit range and approaches the unstable range, the operating range calculator reduces values of the drive signals compared with values of the drive signals calculated when the stability determination value is in the normal range, and outputs the reduced drive signals to limit operating speeds of the arms.