Thrust Cone Lubrication: Part 1: Elastohydrodynamic Analysis of Conical Rims

Thrust rims, or thrust cones, are used to react the axial component of force that occurs between the teeth of single-helical gears. This paper describes a theoretical analysis of hydrodynamic film forming of perfectly conical thrust surfaces. The elastohydrodynamic lubrication (EHL) analysis takes account of elastic deformation and pressure/viscosity effects at the contact between the rims. Application of the theory to a typical large marine reduction gear pair shows that a substantial oil film (typically 10 μm) is generated over most of the contact, but at the edges of the thrust tracks considerable thinning of this film can occur. It is suggested that a self-aligning point contact design would overcome this problem, and analysis of such a design is the subject of a further paper.