Spur gear terminology

Throat form radius is the radius of the throat of an enveloping wormgear or of a double-enveloping worm, in an axial plane. A toothed gear must have an integral number of teeth. The diametral pitch is, by definition, the number of teeth divided by the pitch diameter.

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Gears can mesh as shown in the Figure 2. Please help improve this article by introducing citations to additional sources.

Portion of the arc of year from the pitch point to the end of engagement is the arc of recess i. The point of tangency of the pitch circles of two meshing gears, where the Line of Centers crosses the pitch circles. The relationship between the two shafts is actually defined by the helix angle s of the two shafts and the handedness, as defined: Cone distance in a bevel gear is the general term for the distance along zpur element of the pitch cone from the apex to any given position in the teeth.

The width of a tooth and a space, measured on the pitch circle. Please see Figure 2. The composite action test must be made on a variable center distance composite action test device. In a throated wormgear it is the maximum diameter of the blank. The term applies to external gearsthis is can also be known from major diameter. A harmonic gear or strain wave gear is a specialized gearing mechanism often used in industrial motion controlrobotics and aerospace for its advantages over traditional gearing systems, including lack of backlash, compactness and high gear ratios.

It is also the angle between the line of action and the common tangent. Examples of such sections are the transverse section of bevel gear teeth and the normal section of helical teeth.

Basic Gear Terminology and Calculation

The standard reference pitch diameter is the diameter of the standard pitch circle. One arrangement is called stable, and the other unstable. The most common form of gear cutting is hobbingbut gear shapingmillingand broaching also exist.

In spur and helical gears, unless otherwise specified, the standard pitch diameter is related to the number of teeth and the standard transverse pitch. This arrangement can also remove the need for thrust bearings. While a regular gear is optimized to transmit torque to another engaged member with minimum noise and wear and maximum efficiencya non-circular gear's main objective might be ratio variations, axle displacement oscillations and more.

Cogset Derailleur gears Hub gear Shaft-driven bicycle Sprocket. A gear or cogwheel is a rotating machine part having cut tdrminology, or in the case of a cogwheel, inserted teeth called cogswhich mesh with another toothed part to transmit torque.

List of gear nomenclature

The pitch line corresponds, in the cross section of a rack, to the pitch circle operating in the cross section of a gear. Another method involves tapering the teeth in the axial direction and letting the gear slide in tefminology axial direction to take up slack.

It has also been divided into sub-portions. The addendum circle coincides with the tops of the teeth of a gear and is concentric with the standard reference pitch circle and radially distant from it by the amount of the addendum.

This is called Tip and Root Clearance cthe distance between tooth root and the tooth tip of mating gears. This line is also the common tangent at the point of contact of the mating gears and is known as the line of action or the pressure line. A spur gear has a cylindrical pitch surface and teeth that are parallel to the axis. Equivalent pitch radius is the radius of the pitch circle in a cross section terrminology gear teeth in any plane other than a plane of rotation. Examples are sun and planet gearing see belowcycloidal driveand mechanical differentials.

List of gear nomenclature - Wikipedia

In a pair of gears, backlash is the amount of clearance between mated gear teeth. For the same leadthe helix angle is greater for larger gear diameters. Sometimes, we simply termed the tooth profiles which satisfy the fundamental law of gear-tooth action the conjugate profiles.

This is the case in which the root portions of gear are subjected to a repeated load exceeding the material's fatigue limit. Worm-and-gear sets that do lock are called self lockingwhich can be used to advantage, as when it is desired to set the position of a mechanism by turning the worm and then have the mechanism hold that position. The normals to the gewr of these teeth, at all points of contact, must pass through a fixed point in the common centerline of the two shafts.

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