The AB and AF Series of helical planetary gearheads from Apex Dynamics USA, Holbrook, N.Y. (www.apexdynamicsusa.com), use shaft cage assemblies and input bearing bores machined from a single piece of stainless steel using the same turning center and centerlines. This gives them the 100% concentricity needed for less than 1 arc-min of backlash. This degree of concentricity also improves efficiency and keeps operational noise under 56 dB. The gearheads have input-hub pinion bearings directly behind the single-piece cage assemblies, which let the gearheads handle inputs to 10,000 rpm. Oversized, tapered-roller bearings and fully complemented planetary needle bearings give the gearheads over 30,000 hr of service life and provide up to 6,000 Nm (53,000 lb-in.) of torque. The devices range in size from 42 to 220-mm square and available gear ratios span 3:1 through 100:1.