Type of Gear Max. Pitch Dia Diametral Pitch Face Width Unground Tooth Ground Tooth External Helical Gears 14 inches 5-48 DP 8 inches AGMA 10 AGMA 13 Internal Helical Gears 10 inches 6-48 DP 4 inches AGMA 10 AGMA 13 External Spur Gears 18 inches 3-48 DP 8 inches AGMA 10 AGMA 14 Internal Spur Gears 20 inches 3-48 DP 8 inches AGMA 10 AGMA 14 Involute Splines 18 inches 3/6 - 80/160 DP 8 inches ANSI B92.1 CL.4 ANSI B92.1 CL.4 Straight Bevel Gears 20 inches 3-48 DP 3 inches AGMA 10 Not Applicable Zerol Bevel Gears 12 inches 3-40 DP 2.5 inches AGMA 11 AGMA 13 Spiral Bevel Gears 16 inches 3-40 DP 3 inches AGMA 11 AGMA 13