The gears that have parallel shafts are spur gears, helical gears, and
herringbone gears. These are the gears that mesh in the same plane. They
are used for transmission of rotary motion between parallel shafts. They
offer maximum transmission of power and high efficiency. They are used
in higher horsepower applications where long-term operational efficiency
is more important. They are more expensive to manufacture and create
axial thrust. They have higher load capacity and make less noise. They
are generally used in clocks, movie projector and car steering. They are
widely used for manual transmission.
