Work machine

A work machine comprising:

• a machine body;
• a work equipment mounted on the machine body;
• a hydraulic breaker attached to a distal end of the work equipment;
• a control valve configured to control hydraulic oil fed to the hydraulic breaker;
• a single rod type hydraulic cylinder configured to operate the work equipment downward so that the hydraulic breaker is pressed against an object to be crushed;
• an operation unit configured to operate the hydraulic cylinder in a contracting direction so that the work equipment is operated downward;
• pressure sensors respectively configured to detect pressure at the head side and pressure at the rod side of the hydraulic cylinder so as to detect pressing force of the hydraulic breaker;
• a changeover switch configured to switch the hydraulic breaker between an automatic hammering inhibiting mode, in which operation of the hydraulic breaker is inhibited, and an automatic hammering authorizing mode, in which the hydraulic breaker is automatically operated in a given range of pressing force;
• and
• a controller comprising:
• a condition ascertaining unit configured to output a signal for ascertaining whether the pressures of the hydraulic breaker are in the given range of pressing force based on the pressure at the head side and the pressure at the rod side respectively detected by the pressure sensors;
• a first switching device configured to receive a signal based on an output signal of the condition ascertaining unit and a 0 signal, and output one of the received signals based on the output signal of the condition ascertaining unit and a signal for ascertaining whether the operation unit has been operated;
• and
• a second switching device configured to receive an output signal of the first switching device through a buffer and a 0 signal, and based on an output signal of the changeover switch indicating whether the hydraulic breaker is in the automatic hammering inhibiting mode or the automatic hammering authorizing mode, output one of the received signals as a control signal of the control valve for the hydraulic breaker, wherein
• the first switching device is configured to output the signal based on the output signal of the condition ascertaining unit when the output signal of the condition ascertaining unit indicates that the pressures of the hydraulic breaker are in the given range of pressing force and the signal for ascertaining whether the operation unit ha been operated indicates that the operation unit has been operated, and otherwise output the 0 signal;
• and
• the second switching device is configured to output the 0 signal when the hydraulic breaker is in the automatic hammering inhibiting mode and output the output signal of the first switching device through the buffer when the hydraulic breaker is in the automatic hammering authorizing mode.