However, the advantage of employing gears with separate tooth components is the ability to individually replace the teeth as each becomes fatigued rather than replacing the whole gear component. For most applications, once a gear succumbs to fatigue, it can be replaced in its entirety. There are several common design and construction options available for gear teeth, including:ĭepending on the gear structure, gear teeth are either cut directly into the gear blank or inserted as separate, shaped components into the gear blank. While in the previous section, gears were categorized based on the overall shape of the gear body, this section describes characteristics relating to their tooth (i.e., cog) design and construction. Gear teeth are also referred to as cogs, hence why a gear is also called by the somewhat archaic term of cogwheel. Additionally, linear gears, such as gear racks, can convert the rotational motion of the driving gear into the translational motion (or a combination of translational and rotational motion) of the driven gear.
Variable speed and torque enable non-circular gears to fulfill special or irregular motion requirements, such as alternatingly increasing and decreasing output speed, multi-speed, and reversing motion. On the other hand, devices and systems which employ non-circular gears experience variable speed and torque ratios. The constancy of the gear ratio means that given the same input (either speed or torque), the device or system consistently provides the same output speed and torque. These gears can feature elliptical, triangular, and square-shaped faces.ĭevices and systems which employ circular gears experience constancy in the gear ratios (i.e., the ratio of the output to the input) expressed-both for rotary speed and torque. Most types of gears are circular-i.e., the gear teeth are arranged around a cylindrical gear body with a circular face-but some non-circular gears are also available. These various characteristics allow gears to be classified and categorized in several different ways, which include: Gears are available in a variety of designs, constructions, and configurations to suit a wide range of industries and applications. Additionally, this article outlines the selection considerations and common applications for each type of gear. This article focuses on gears, exploring the various types available and explaining their respective functions and mechanisms. Each of these gears offers different behaviors and advantages, but the requirements and specifications demanded by a particular motion or power transmission application determine the type of gear most suitable for use. Other design characteristics, including construction material, gear shape, tooth construction and design, and gear pair configuration, help to classify and categorize the various types of gears available. Gears and their mechanical characteristics are widely employed throughout industry to transmit motion and power in a variety of mechanical devices, such as clocks, instrumentation, and equipment, and to reduce or increase speed and torque in a variety of motorized devices, including automobiles, motorcycles, and machines. Additionally, if the gears are not of equal sizes, the machine or system experiences a mechanical advantage which allows for a change in the output speed and torque (i.e., the force which causes an object to rotate). Depending on the design and construction of the gear pair, the transference of motion between the driving shaft and the driven shaft can result in a change of the direction of rotation or movement. Each gear or toothed component is attached to a machine shaft or base component, therefore when the driving gear (i.e., the gear that provides the initial rotational input) rotates along with its shaft component, the driven gear (i.e., the gear or toothed component which is impacted by the driving gear and exhibits the final output) rotates or translates its shaft component. Operating in mated pairs, gears mesh their teeth with the teeth of another corresponding gear or toothed component which prevents slippage during the transmission process. Gears are toothed, mechanical transmission elements used to transfer motion and power between machine components, and in this article, we discuss the different types of gears available and how gears work. Illustration of the different types of gears available.