generally operate quietly, even under heavy loads.
c. Herringbone. Herringbone gears (fig. 19-5)
can be formed by attaching two helical gears in such a
way that their teeth meet in a V-formation. The V-
configuration cancels the side thrust created by each
helical gearset. As herringbone gears mesh, more than
one tooth is engaged at a time. This feature allows the
gear to transmit large amounts of torque and operate
d. Bevel. Bevel gears (fig. 19-5) generally are
used to change direction. Their teeth are machined at
angles to the drive centerline to correspond with the
Figure 19-4. Internal and External Gears.
angle of input and output shafts. Bevel gears, like spur
gears, engage one
Figure 19-5. Types of Gears