Email(630) 543-6640

CNC Gear Machining of a Steel Zerol Bevel Pinion for the Aerospace Industry

Trusted by many firms in a diverse array of industries, Reliance Gear Corporation has been manufacturing custom gear parts since 1965. When a customer in the aerospace industry needed a thin walled, complicated steel zerol bevel pinion, Reliance Gear was contracted to complete the project. Our company was there at the beginning stages of development, using our Hӧfler® ZP350 we created TCA/bearing pattern files which are stored and used as master files. This part was manufactured using 4340 steel, utilizing our CNC Mazak Nexus® lathe, parts were then tooth cut on one of our Gleason Phoenix® CNC #250HC generators. The internal spline was generated using a #20-4 Fellows® gear shaper. After heat treating these parts, distortion was eliminated in the internal spline areas using a custom designed spline lapper. The bevel teeth were ground using our CNC Gleason® #600 bevel tooth grinder.

Evaluating the bevel teeth bearing pattern had to be done using strict parameters of load and RPM. Strict process control must be maintained in order to obtain the tight tolerances, some which are measured after the selective application of Thin Dense Chrome and Titanium-Cadmium plating. Other selective areas of this part require strict applications of primer and enamel coatings. This is of course done after 100% dimensional and non-destructive integrity inspections are completed.

These complex pinions have an outside diameter of 2.799", and a length of 2.892". The bevel pinions have 18 teeth, a D.P. of 6.4547, a P.A. of 25°, and a spiral angle of 0° - LH. The internal spline has 28 teeth, a D.P. of 16/32, and a P.A: 30°. We achieve tolerances of 0.0006" on a 0.7869" diameter having a 16 RMS finish and 0.0004" on a 2.1648" diameter holding a 32 RMS.

To learn more about this project or to find out how Reliance Gear can help with your complex gear machining project, please take a look at the following chart or contact us directly.

Steel Zerol Bevel Pinion Project Highlights

Capabilities Applied/Processes
CNC Turning
Cut Spiral Bevel
Gear Shaping
O.D. Grinding
I.D. Grinding
Gear Grinding
Spline Lapping
Heat Treating
Part Marking
Titanium Cadmium Plating
Thin Dense Chrome Plating
Primer/Enamel Coating
Equipment Used to Manufacture Part
Mazak Nexus CNC, Gleason Phoenix CNC # 250HC, Fellows Gear Shaper #20-4, Gleason CNC Bevel Tooth Grinder #600G, Studer CNC Grinder #S30, Okuma CNC Grinder #G1-20N
Overall Part Dimensions
Outside Diameter: 2.799
Length: 2.892
Bevel Gear Data
  • Number of Teeth: 18
  • D.P.: 6.4547
  • P.A.: 25°
  • Spiral Angle: 0° - LH
Internal Spline
  • Number of Teeth: 28
  • D.P.: 16/32
  • P.A.: 30°
Tightest Tolerances
0.7869/0.7863 = 0.0006" Total, Front Hub Diameter
2.1648/2.1644 = 0.0004" Total, Bearing Hub Diameter
Material Used
4340 Steel
Material Finish
  • Titanium Cadium Plating - Selective
  • Chrome Plating - Selective
  • Painting - Selective
In process testing/inspection performed
Dimensional Inspection, Visual Inspection, Nital Etching
Magnetic Particle Inspection, Gear Inspection, Hardness Test
Industry for Use
Standards Met
Customer Specifications