Ring and Pinion Tooth Contact Patterns

Ring and Pinion Gear.

Apply tooth contact compound to the ring gear in two different places. Carefully apply moderate pressure to the outside ring gear. Use something soft like a small block of wood. Rotate the pinion to turn the ring gear four complete revolutions on the drive side and then four in the opposite direction for the coast side. The following are typical ring gear patterns. Check with the manufacturer’s manual for specifications or any special procedures.

Ideal ring and pinion tooth contact pattern.

This is an ideal ring gear tooth contact pattern. It's centered between the top and the bottom of gear’s teeth.

The coast side of a ring gear.

This is also an ideal contact pattern. This is the coast side of the ring gear.

Excessive backlash; ring and pinion tooth contact pattern

When the pattern is located toward the heel or outside of the ring gear, there's too much or excessive backlash. Moving the ring gear toward the pinion will remove the backlash and move the contact pattern closer to the toe.

Insufficient backlash; ring and pinion tooth contact pattern

This is the opposite of C. The ring gear is too far in toward the pinion; there is insufficient backlash. Moving the ring gear away from the pinion will increase backlash and cause the pattern to move out toward the heel or the outside of the ring gear.

Excessive pinion; ring and pinion tooth contact pattern

This pattern indicates excessive pinion depth. When the pinion is too far in towards the ring gear the pattern will be low toward the base of the gear teeth. Moving the pinion in toward the ring gear causes the pattern to move toward the bottom or root of the gear teeth. Moving the pinion away from the ring gear causes the pattern to move up toward the top of the gear’s teeth.

Insufficient pinion; ring and pinion tooth contact pattern

This pattern indicates that the pinion is too far away from the ring gear. Moving the pinion in toward the ring gear causes the pattern to move in towards the root of the gear’s teeth.