The work analyses contact stresses that occur within the active surface of toothed gears as well as bending stresses that take place at the tooth root. Contact stresses have been designated at the beginning of the singletooth engagement area within the pitch point and in the end of single-tooth engagement area. Designation of bending stresses at the tooth root has been made by applying the interteeth force to the external point of single-tooth engagement. The calculated numerical values of contact and bending stresses were compared to fatigue contact durability σH lim and fatigue bending strength σF lim that were obtained experimentally. Calculations of contact stresses and bending stresses were done with multi-criterion optimisation, which makes it possible to select such geometrical parameters of toothed gears that allow utilizing fatigue durability σH lim and σF lim in reference to a given material and technology of manufacturing toothed gears.

This work is an analysis of gear slippage and contact stresses in toothed gears of a six-shaft power shift gearing. Gear meshing contains 5 characteristic contact points located within the active surface of a tooth. The contact points are as follows: A – beginning of a tooth involute profile located within double-tooth engagement area; B – the end-point of double-tooth engagement constituting the beginning of single-tooth engagement area; C – pitch point, referred to also as the central contact point; D – the last point of the single-tooth engagement being at the same time the starting point of the double-tooth engagement area, which is a part of the tooth tip; and, E – point at the tooth tip that closes the double-tooth engagement area. The location of individual contact points and the resulting slippage and contact stress values depend on the geometrical parameters of cooperating gear wheels. The inter-relationship suggests that, in power shift gearings, the contact points have as many positions within the active surface as there are cooperating gear wheels.