Polygon Functional Benefits

• Polygon systems provide the highest torque carrying capacity, within the shaft diameter, of any drive connection. This has been demonstrated by torsion test to the failure point illustrated in this photo (below). The photo shows the result of such test on a steel bar that has been ground with a P3 form on one end, and a spline on the other. The cross sections of both forms fit into the same circle diameter. The effect of stress risers in the spline is obvious.
  

• The smooth polygon profiles, with no sharp corners, eliminate stress concentration risers; hence provide twice the shear strength of involute spline.

• Polygons are ground between centers, after shafts are hardened, provide excellent concentricity; and the polygon grinder ability for cylindrical grinding, permits grinding of shafts and bores for bearing fittings in the same set-up.

• The Self-centering characteristics of polygon profile provide a "floating fit" at high-speed connections. This self-centering means better balancing at high speeds.
  

• The high strength of the polygon connections, with no runout requirement, makes it possible to reduce the size needed by other connections. This helps designs where space or weight limitation is a concern.
  

• The close fits of polygon profiles provide reduced backlash. Zero backlash can be achieved with taper polygons, or polygon press fit connections.
  

• The reduced backlash, and high strength of the polygon connections make them capable of withstanding greater shock loads under extreme torque reversal conditions, such as occur on brakes, transmissions, oil drilling and mining equipments, and other similar applications.

• The accuracy of manufacturing of the shafts and bores allow holding +/- 15 minutes angular orientation even along relatively long shafts.
  

• In most cases, interchangeability of any group of polygon connections is readily obtainable without special matching. The standard polygon profiles are easily held to very close tolerances with no difficulty. On occasion however, where super-accurate requirements are called for, these can be provided by matching.

• For a combination of size accuracy, strength, ease of assembly, and zero backlash, the tapered polygon torque connection cannot be surpassed.