Dynamic Loads on Spur Gear Teeth Having Pitch Errors at High Speed

Dynamic loads on spur gear teeth are examined by a gear testing machine and a strain gauge apparatus. The ground pinion and gear are tested at the perithery velocity 80 m/sec and below. Some teeth of the gear have normal pitch errors of about 15μ which are given on purpose. The magnitude of the dynamic load increases at the critical speed at which the meshing frequency is equal to the natural frequency of the vibratory system consisting of the pinion, the gear and the combined tooth stiffness. At a speed over the critical one, a heavy dynamic load occurs on the tooth which has a protruded error. If there is a tooth which has an indented error, the tooth tends to carry no load, and a heavy dynamic load will occur after several teeth. The calculated results, which are analysed as a vibration problem, are nearly coincident with the measured results.