Abnormality diagnosis device for planetary gear speed reducer and construction machine

An abnormality diagnosis device for a planetary gear speed reducer in a construction machine that is driven by a hydraulic motor and the planetary gear speed reducer coupled to an output shaft of the hydraulic motor, comprising:

• a first vibration sensor attached to a speed reducer housing that is a housing of the planetary gear speed reducer and configured to sense vibration of the speed reducer housing;
• a second vibration sensor attached to a motor housing that is a housing of the hydraulic motor and configured to sense vibration of the motor housing;
• and
• a processor configured to determine presence or absence of abnormality in a plurality of gears included in the planetary gear speed reducer on a basis of sensing results acquired by the first vibration sensor and the second vibration sensor, wherein
• the processor is configured to
• compute a peak frequency corresponding to a peak period of vibration of the hydraulic motor and a speed of rotation of the hydraulic motor from second vibration data acquired by the second vibration sensor,
• compute characteristic frequencies corresponding to respective rotation periods of the plurality of gears on a basis of the speed of rotation of the hydraulic motor, number of the plurality of gears, and number of teeth of each of the plurality of gears, and
• determine presence or absence of abnormality in the plurality of gears on a basis of the peak frequency of the hydraulic motor and amplitudes at the characteristic frequencies of first vibration data acquired by the first vibration sensor.