{"data":{"fields":"term_definition","term_definition":"<div class=\"definition\">The Face Contact Ratio is the ratio of the face advance to the circular pitch for spiral bevel and hypoid gears. The face advance being the arc subtended by a cone element to the inner end of one tooth and a cone element to the outer end of the same tooth. The face advance is of course measured at the pitch circle of the gear. For a given circular pitch and face width, the Face Contact Ratio will vary directly with the spiral angle. The spiral angle should be great enough to give a Face Contact Ratio of at least 1.25 and for maximum smoothness, the Face Contact Ratio should be between 1.5 and 2.0. Design values influencing the Face Contact Ratio are the spiral angle, the face width and the circular pitch. An increase in either of the first two and decreasing the last will all cause an increase of the Face Contact Ratio.<\/div>"}}