Bulletproofing a Ring and Pinion Gear


Bulletproofing a Ring and Pinion Gear walker wilkerson

Most aerospace shotpeening job shops will know exactly what you are talking about when you specify this but if they blink and look at you blankly, find another place.  True shotpeening is not cleaning in a blast cabinet at your local machine shop but a specialized process.


Looking at the pinion head you can see the stippled surface of the shotpeening.  It is hard to shotpeen a nitrided surface and you must use hardened shot and high velocities to effectively do it.  It is hard to see the effects with the naked eye.

Finally we finished the gears with WPC Processing. For details on how WPC works check Here!

WPC is the Japanese process we love where the parts are hit with very small, very hard spherical ceramic and metallic dry lubricant elements at ultra high speeds.  WPC leaves a very fine, hard, wear resistant and low friction surface finish which has superior grain refinement and development of compressive stress at a shallower depth when compared to shotpeening, of about one thousandth of an inch.


We shotpeened the splines and the shaft undercut although we masked off the smoothly ground bearing area to the left.  Using 220 small shot and 330 big shot allows even treatment of splines and the tight radius of the gear teeth.

WPC can also be applied to delicate parts and gets easily to the bottom of gear teeth and shaft spline roots.  WPC greatly reduces friction and heat buildup and reduces power loss through the drivetrain.  WPC has no negative side effects and greatly strengthens, increases life and reduces friction on parts.  WPC usually also results in a 100% or greater improvement in fatigue strength with improvements in surface hardness and improvements in tensile strength as well.


Shotpeened surface on the ring gear.

To complete the prep of Walker's diff we sent him some of Amsoil’s new 250 weight severe duty synthetic gear oil.  Our friends that race in the Lucas off road truck racing series have reported to us that this gear oil has just about eliminated failures of their transmissions and differentials.  Some teams were replacing these units every race and now report that the parts don’t fail with this oil.  We usually use Redline shockproof heavy in severe duty applications but we have been testing Amsoil with good results in transmissions and diffs so far.


After shotpeening we subjected everything to WPC treatment.  Since it does not damage or distort delicate metal surfaces we treated the entire pinion shaft and bearing as well as the gear teeth.  Note the smooth and lustrous slippery WPC surface.

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