The previous chapter clearly illustrates that worm gears from the earliest times were an essential machine component. They are more widely used today than ever in the past, because of their many unique advantages. Having gained the broadest possible acceptance, worm gears are used in almost every type of machine. This wide-spread usage is due to a number of reasons, that range from mass production of standardized catalog units (that are available for immediate delivery) to the advantages of the sliding tooth interacting with rolling action. These are the features that provide high strength and low audibility combined with long life.
Because of the worm gear's screw like action, such drives are vibration free and produce constant output speed free from pulsations. Worm gearing is compact, providing large ratios in an envelope smaller than that required for other types of gearing. In the higher ratios advantage can be taken of the worm gear's inability to drive backwards, i.e., self locking.
The statement can be made: “In no other form of machine is the mechanical advantage likely to be greater than in the screw. The worm gear is a form of screw and takes full use of the inherent mechanical advantage. This is the basic mechanical application of the inclined plane. A plane that is rolled up or helical.
