No-load Kinematics


The no-load kinematical behavior of a gear set is a fundamental gear mesh characteristic that should never be overlooked.
The basic kinematic characteristics include:
  • the location and size of the Contact Patterns (blue patch below) on the tooth flank of the gear member;
  • the Path of Contact (PoC; red dotted line below), i.e. the locus of the numerically unique contact points between the meshing pinion and gear teeth, and the Bias of the PoC, i.e. its inclination on the tooth flank;
  • the Ease Off surfaces, which show in 3D how much relief the meshing tooth flanks have in the length wise and profile wise directions;
  • the Transmission Error curves, which reveal how smoothly rolling motion is transmitted between the meshing teeth.
The figure below shows the HyGEARS TCA display (i.e. the no-load Tooth Contact Analysis) for a typical spiral-bevel gear set.
In a single view, a relatively experienced gear engineer can judge whether the gear set will perform correctly by looking at the size and location of the Contact Patterns, the Bias of the PoC, the Backlash, the Contact Ratio, the amount of relief on the Ease Off surfaces and, especially, the shape of the Transmission Error curves and their amplitude at the transfer points, plus the clearances between the tooth tip of one member and the tooth root of the mating member.
In other words, in a single glance, the gear engineer can judge all the important kinematical characteristics of the gear set.
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