Double Helical Gears

Double Helical Gears or Herringbone Gears are commonly used in parallel shaft transmissions especially when a smooth continues action is essential as in high speed.

Where the pitch-line velocity may range from about 1000 to 3000 feet per minute in commercial gearing and up to 12,000 feet per min or higher in more specialised installations these relatively high speed are encountered in Marine reduction gears in certain speed reducing and speed increasing units.

And in various other transmissions, particularly in connection with steam turbine and electric motor drives