Study of the performance of a worm gearing transmission enhanced by hydrostatic lubrication

The feasibility of a hydrostatically lubricated wormgear transmission is studied. The geometrical parameters for a double-enveloping wormgear, intended to be used in the transmission, are determined. The geometrical properties of the selected wormgear are analyzed by using the method of enveloping. The load sharing between the meshing teeth is analyzed based on a hypothesis of load sharing. The mathematical problem of lubrication at the tooth contact is formulated by considering the hybrid (hydrostatic and hydrodynamic) lubrication effects and the dependence of the oil properties on pressure and temperature. A capillary flow restrictor is designed to be used in the application. The lubricant flow through the restrictor is analyzed by considering the compressibility and thermal effects. The mathematical problem of lubrication is solved by numerical iterations.Results of computation are presented that include the detailed pressure and temperature distribution in the oil film, the supply pressure needed to maintain a prescribed minimum oil film thickness, the fluid friction acting on the meshing surfaces, the mass flow rate of supply oil, and the power loss associated with the restrictor flow. The feasibility of the hydrostatically lubricated wormgear transmission is discussed in light of these results.The local operating line method is introduced to simplify the calculation of the temperature distribution in the oil film. The Moody friction factor is used to model the friction loss in the restrictor flow, whose mean temperature is determined by applying the operating line method.