INTERNAL GEARS - Quality Transmission Components - #1

Table 4-6 presents the method for calculating the mesh of a rack and spur gear. Figure 4-9a shows the pitch circle of a standard gear and the pitch line of the rack.

One rotation of the spur gear will displace the rack I one circumferential length of the gear's pitch circle, per the formula:

I = 71 mz (4-6)

Figure 4-9b shows a profile shifted spur gear, with positive correction xm, meshed with a rack. The spur gear has a larger pitch radius than standard, by the amount xm. Also, the pitch line of the rack has shifted outward by the amount xm.

Table 4-6 presents the calculation of a meshed profile shifted spur gear and rack. If the correction factor ^ is 0, then it is the case of a standard gear meshed with the rack.

The rack displacement, /, is not changed in any way by the profile shifting. Equation (4-6) remains applicable for any amount of profile shift.

Figure 5-1 presents the mesh of an internal gear and external gear. Of vital importance is the operating (working) pitch diameters, d_w, and operating (working) pressure angle, oc_w. They can be derived from center distance, a_x, and Equations (5-1).

«w = ^{c o s 1 (}—2a—⁾

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