Abstract: A dynamic model of tranxmission of spiral bevel gears is established.The model involves linear and angular vibrations of gears in every direction. Torsional deformations of webs of gears and input,output-shafts are considered.The governing equations of this model derived in this paper are multifreedom,timevarying and parametric differential equations。Purther,after neglecting the second order small components,they are transformed into constant coefficlent equa-tions,and:olved successfully. The dynamic responses and loads on gears in transmission are ob-tained.The dynamic loads at variable speeds of gears make up the dynamic behaviour of this pair of gears,which provides the basis for structural vibrations and strength analysis of spiral bevel gears.

Key words: spirals-gear, vibration tests, excitation-parameterization