The cutting tool nomenclature pdf of the gear blank at the outer ends of the teeth is customarily formed to such a back cone. Another source defines it as the maximum distance through which one part of something can be moved without moving a connected part.
It is also called lash or play. In a pair of gears, backlash is the amount of clearance between mated gear teeth. Backlash is unavoidable for nearly all reversing mechanical couplings, although its effects can be negated. Depending on the application it may or may not be desirable. It is measured along the mutual perpendicular to the axes, called the line of centers.
It applies to spur gears, parallel axis or crossed axis helical gears, and worm gearing. In the usual case with axes at right angles, it contains the worm axis. The composite action test must be made on a variable center distance composite action test device. Outer cone distance in bevel gears is the distance from the apex of the pitch cone to the outer ends of the teeth. When not otherwise specified, the short term cone distance is understood to be outer cone distance. Inner cone distance in bevel gears is the distance from the apex of the pitch cone to the inner ends of the teeth. The normals to the profiles of these teeth, at all points of contact, must pass through a fixed point in the common centerline of the two shafts.
Usually conjugate gear tooth is made to suit the profile of other gear which is not made based on standard practice. There is theoretically point contact between the teeth at any instant. They have teeth of the same or different helix angles, of the same or opposite hand. A combination of spur and helical or other types can operate on crossed axes. It is properly the radius of curvature of the pitch surface in the given cross section.
Examples of such sections are the transverse section of bevel gear teeth and the normal section of helical teeth. A face gear has a planar pitch surface and a planar root surface, both of which are perpendicular to the axis of rotation. For double helical, it does not include the gap. Total face width is the actual dimension of a gear blank including the portion that exceeds the effective face width, or as in double helical gears where the total face width includes any distance or gap separating right hand and left hand helices. For a cylindrical gear, effective face width is the portion that contacts the mating teeth. One member of a pair of gears may engage only a portion of its mate.