OPERATION OF A SPIROID GEAR UNDER ELASTOHYDRODYNAMIC LUBRICATION CONDITIONS

Spiroid gears are used in the drive systems of various types of vehicles and devices. They are characterised by small overall dimensions and significant rotational speed reduction while maintaining the high positioning accuracy of the driven device. Spiroid gears require a lot of lubrication with oils, which separate the mating parts. In the case of spiroid gears, they separate the face wheel teeth and the worm thread. The resulting oil film reduces the coefficient of friction and lowers the temperature of the mating surfaces. The modelling of toothed rim lubrication is a complex problem. To separate the surface of the face wheel mating and the worm, one needs to consider the phenomena of fluid mechanics, heat transfer and tooth deformation. The formation of an elastohydrodynamic oil film of an appropriate height is determined by the type of oil, the mechanical properties of the worm and face wheel materials, relative speed, load and the geometry of the mating surfaces. The issues described in this paper significantly affect the correct operation of gears and have not yet been fully understood for spiroid gears. This paper presents the results of a study on the properties of the elastohydrodynamic oil film and describes its characteristics, with the unknown quantity being the rotational speed of the input shaft that ensures that the oil film separates the mating toothed rims. The calculation results were compared with those of other researchers. The obtained design recommendations can help designers improve the durability and reliability of spiroid gears.