Design Tips

• Most often, either three-lobe (P3), or four-lobe (PC4) profile can be used. A few rules determine when to use either of them. P3 is used for most of the fixed connections, and when zero backlash is required, especially for frequently separated connections. In later case a tapered P3 must be used. The taper prevents a connection from self-locking, by using a 10 degrees included angle, or steeper tapers. Because torque on the tapered profile, also generates an axial separating force, a fastener or lock nut is required.

• Most of the sliding connections use the PC4 profile. However, P3 is acceptable with very low torque and high actuating force, as in hydraulic cylinders, and when sliding occurs under no-load.

• PC4 sliding connections require greater force for axial movement under torque load than do straight-sided splines. At zero torque load, they perform equally well, and often better than involute splines.

• When a hub-wall thickness is insufficient for the design load, reducing its bore diameter can strengthen the wall. Often overall connection strength slightly changes.

• Polygon potential benefits "Increased strength, smaller space requirements, lighter weight, self-centering characteristics, simplified manufacturing techniques, concentricity, angular orientation accuracy" are maximized when systems are totally designed around Polygons from the outset.