#GEAR TOOTH GEOMETRY CALCULATOR HOW TO#

The helical gear differs from the spur gear in that its teeth are twisted along a helical This results in a reduction ratio of 1/30. In Figure 5-2 the gear train has a difference of numbers of teeth of only 1 z 1 = 30 and Reduction ratio in one step, such as 1/100. Of teeth is small, belong to the field of hypocyclic mechanism, which can produce a large In order to assemble successfully, the external gear shouldīe assembled by inserting in the axial direction.Ī profile shifted internal gear and external gear, in which the difference of numbers

#GEAR TOOTH GEOMETRY CALCULATOR HOW TO#

Table 5-4 is an example of how to prevent interference under the conditions of z 2 = 50 and theĭifference of numbers of teeth of two gears ranges from 1 to 8.Īll combinations above will not cause involute interference or trochoid interference, but Of teeth of two gears is quite small, a profile shifted gear could prevent the interference. In the meshing of an internal gear and an external gear, if the difference in numbers The number of teeth of the pinion cutter ranges from 15 to 19 ( z c = 15 to 19).ĥ.3 Internal Gear With Small Differences In Numbers Of Teeth The correction, x c, is the magnitude of shift which was assumed to be: x c = 0.0075 z c + 0.05. Table 5-3b shows the limit for a profile shifted pinion cutter to prevent trimming interference while cutting a standard internal gear. The number of teeth of the pinion cutter ranges from 15 to 22 ( z c = 15 to 22). There will be an involute interference between the internal gear and the pinion cutter if Gear, with pressure angle 20°, and no profile shift, i.e., x c = 0. The limit for the pinion cutter to prevent trimming interference when cutting a standard internal Should that happen, there is danger of breaking the tooling. This type of interference can occur in the process of cutting an internal gear with a When the numbers of teeth of the two gears are very close. Mesh must be assembled by sliding the gears together with an axial motion.

This occurs in the radial direction in that it prevents pulling the gears apart. Interference is avoided if the difference of the number of teeth, z 1 – z 2, is larger than 9. In the meshing of an external gear and a standard internal gear α = 20°, trochoid Where α a1 is the pressure angle of the spur gear tooth tip: The condition for avoiding trochoidal interference. It tends to happen when theĭifference between the numbers of teeth of the two gears is small. The dedendum of the internal gear during recess tooth action. This refers to an interference occurring at the addendum of the external gear and

Where α a2 is the pressure angle seen at a tip of the internal gear tooth.Įquation (5-3) is true only if the outside diameter of the internal gear is bigger than the base circle:įor a standard internal gear, where α = 20°, Equation (5-5) is valid only if the number of

Involute interference can be avoided by the conditions cited below: It is prevalent when the number of teeth of the external gear is small. This occurs between the dedendum of the external gear and the addendum of the internal gear. Three different types of interference can occur with internal gears: In order to get a correct tooth profile, the coefficient of cutter should be taken into consideration. That is because the cutter has a coefficient of shifted profile. Of tooth depth and root diameter, after cutting, will be slightly different from the calculation. Pinion cutters are often used in cutting internal gears and external gears. If the center distance, a x, is given, x 1 and x 2 would be obtained from the inverse calculationįrom item 4 to item 8 of Table 5-1. It will become a standard gear calculation if x 1 = x 2 = 0.

Table 5-2 Table 5-1 shows the calculation steps.

Gear tooth geometry calculator