The meshing of standard spur gears means the reference circlesof two gears contact and roll with each other. The calculation formulas are in Table 4.1.įig. of Teeth z 1 + z 2 2a / m 36 5 Number of Teeth z z 1 + z 2 / i + 1 i (z 1 + z 2) / i + 1 16 20 Item Symbol Formula Example Pinion (1) Gear (2) 1 Module m Set Value 3 2 Center Distance a 54.000 3 Speed Ratio i 1.25 4 Sum of No. Note, that the number of teeth will probably not be integer values when using the formulas in Table 4.2. In this case,it will be necessary to resort to profile shifting or to employ helical gears to obtain as near a transmission ratioas possible.įigure 4.2 shows the meshing of a pair of profile shifted gears.
These values are obtainable from themodified center distance and the following formulas : The key items in profile shifted gears are the operating(working) pitch diameters (d w) and the working (operating) pressure angle (α w). In the meshing of profile shifted gears, it is the operating pitch circle that is in contact and roll on each other thatportrays gear action. Table 4.3 presents the calculations where the profile shift coefficient has been set at x 1 and x 2 at the beginning. This calculation is based on the idea that the amount of the tip and root clearance should be 0.25m.įig.
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