INFLUENCE OF SURFACE-TREATMENT, TOOTH FORM AND LUBRICATING OIL ON LOAD-CARRYING CHARACTERISTICS OF CROSSED HELICAL GEARS

Crossed helical gears are engaged geometrically in a point contact bet ween two tooth surfaces, but this contacting point-changes to an ellip tic contact due to elastic deformation of tooth surfaces under applied load. Therefore, the contacting area between two contacting tooth sur faces is quite small, so that the Hertzian pressure on the tooth surfa ce is comparatively high. Since the sliding speed is also very high, t he limiting load for scoring is low and the wear is comparatively high . Although crossed helical gears can transmit only light loads, they h ave many advantageous features; e.g., the crossed helical gears are ea sy to produce and mounting error has no effect on engagement; Therefor e, in practice, one of the major problems is to find a way to increase the load-carrying capacity of crossed helical gears. In this study we examined limiting load for scoring, specific wear and friction loss o f crossed helical gears with various kinds of surface treatments. We f ound that the influences of surface treatment and lubricating oil on l imiting load for scoring are very strong, which is useful in practical applications, particularly from the viewpoint of power transmission.