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Of the radial pitch, p t, and number of teeth.Īccording to the equations of Table 6-7, let radial pitch p t = 8 mm and displacement>

The displacement of the helical rack, l, for one rotation of the mating gear is the product To mesh a helical gear to a helical rack, they musthave the same helix angle but with opposite hands. Normal coefficient of profile shift x n = 0. The formulas of a standard helical rack are similar to those of Table 6-6 with only the Similarly, Table 6-7 presentsĮxamples for a helical rack in the radial system (i.e., perpendicular to gear axis). With normal module and normal pressure angle standard values. Table 6-6 presents the calculation examples for a mated helical rack Viewed in the normal direction, the meshing of a helical rack and gear is the same asĪ spur gear and rack. Table 6-5 presents equations for a Sunderland gear. The only differences from the radial system equations of Table 6-3 are those for addendum and whole depth. The radial pressure angle, α t, and helix angle, β, are specified as 20° and 22.5°, respectively. The other component is the tangential force.Table 6-7 6.10.3 Sunderland Double Helical GearĪ representative application of radial system is a double helical gear, or herringbone gear, The radial force can be calculated as,Ĭonsidering the axial plane, the axial force is one component of the force. The tangential force is then given by,Ĭonsidering the projection of the normal force in the transverse plane, the tangential force is one component the other component is the radial force. The moment generated by the tangential force at pitch circle equals the applied torque. The tangential force, $F_t$, is tangent to the operating pitch circle in the transverse plane. Although the force is distributed, the operating pitch circle can be taken as an approximation to the average location for the point of contact.

Because of static equilibrium, the sum of this distributed force must equal the torque applied to the gear. The normal force is distributed along the contact line, which moves as the gears rotate.