TM 10-3930-671-24 Spiral Bevel & Hyphoid Tooth Bearing Contact Chart BACKLASH BACKLASH SHOULD BE MEASURED WITH A DIAL INDICATOR RIGIDLY MOUNTED WITH THE STEM PERPENDICULAR TO THE TOOTH SURFACE AT THE EXTREME HEEL. F-318 All  contact  bearings  shown  below  are  on  right-hand  spiral  ring gear - the drive is on the convex side of the tooth. FIG. 1 TYPICAL PREFERRED BEARING ON BOTH SIDES OF TOOTH WHILE UNDER A LIGHT LOAD. FIG. 2 TOE BEARING ON BOTH SIDES OF TOOTH - GEAR SET NOISY. TO MOVE BEARING TOWARD HEEL INCREASE BACKLASH WITHIN LIMITS BY MOVING GEAR AWAY FROM PINION. FIG. 3 HEEL BEARING ON BOTH SIDES OF TOOTH - GEAR SET NOISY AND COULD RESULT IN EARLY GEAR FAILURE. TO MOVE BEARING TOWARD TOE, DECREASE BACKLASH WITHIN LIMITS BY MOVING GEAR TOWARD PINION. FIG. 4 LOW BEARING ON GEAR AND HIGH BEARING ON PINION. CORRECT BY PULLING PINION AWAY FROM GEAR (INCREASE MOUNTING DISTANCE). FIG. 5 HIGH BEARING ON GEAR AND LOW BEARING ON PINION. CORRECT BY MOVING PINION IN TOWARD GEAR (DECREASE MOUNTING DISTANCE). All contact bearings shown below are on the right-hand spiral ring-gear-the drive is on the convex side of the tooth.