ABNORMALITY DIAGNOSING DEVICE FOR PLANETARY GEAR SPEED REDUCER, AND CONSTRUCTION MACHINE

An abnormality diagnosis device for a planetary gear speed reducer includes a second vibration sensor attached to a housing of a hydraulic motor having an output shaft coupled to the planetary gear speed reducer. A controller computes a peak frequency Fm of the hydraulic motor and a speed of rotation of the hydraulic motor on the basis of second vibration data acquired through the second vibration sensor, compute, on the basis of the computed speed of rotation, the number of a plurality of gears included in the planetary gear speed reducer, and the number of teeth of each of the gears, characteristic frequencies fd of the plurality of gears, and determines presence or absence of abnormality in the plurality of gears on the basis of the peak frequency Fm of the hydraulic motor and amplitudes at the characteristic frequencies fd of first vibration data acquired through a first vibration sensor attached to the planetary gear speed reducer.