INTERNAL GEARS0 pages

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, dw, and operating (working) pressure angle, ocw. They can be derived from center distance, ax, and Equations (5-1).

«w = cos1(ח2a)

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