Machinery's Handbook, 31st Edition
Polygon Shafts 2361 Polygon-Type Shaft Connections.— Involute-form and straight-sided splines are used for both fixed and sliding connections between machine members such as shafts and gears. Polygon-type connections, so called because they resemble regular polygons but with curved sides, may be used similarly. German DIN Standards 32711 and 32712 include data for three- and four-sided metric polygon connections. Data for 11 of the sizes shown in those Standards, but converted to inch dimensions by Stoffel Polygon Systems, are given in the accompanying table. Dimensions of Three- and Four-Sided Polygon-Type Shaft Connections Drawing for 3-sided Designs Drawing for 4-sided Designs
B max
2e
D M
R
D A D I
Q
D A D I
B max
2e
Four-Sided Designs
Three-Sided Designs
Nominal Sizes
Design Data
Nominal Sizes
Design Data
Area (in. 2 ) 0.194 0.302 0.434 0.594 0.765 0.977 1.208 1.450 1.732 2.378
Area (in. 2 )
D A (in.)
D I (in.)
e (in.)
Z P (in. 3 ) 0.020 0.039 0.067 0.108 0.153 0.224 0.314 0.397 0.527 0.850 1.260
D A (in.)
D I (in.)
e (in.)
Z P (in. 3 )
0.530 0.665 0.800 0.930 1.080 1.205 1.330 1.485 1.610 1.870 2.140
0.470 0.585 0.700 0.820 0.920 1.045 1.170 1.265 1.390 1.630 1.860
0.015 0.020 0.025 0.027 0.040 0.040 0.040 0.055 0.055 0.060 0.070
0.500 0.625 0.750 0.875 1.000 1.125 1.250 1.375 1.500 1.750 2.000
0.415 0.525 0.625 0.725 0.850 0.950 1.040 1.135 1.260 1.480 1.700
0.075 0.075 0.125 0.150 0.150 0.200 0.200 0.225 0.225 0.250 0.250
0.155 0.250 0.350 0.470 0.650 0.810 0.980
0.014 0.028 0.048 0.075
0.12 0.17 0.22 0.29 0.39 0.64
1.17 1.43 1.94 2.60
3.090 0.92 Dimensions Q and R shown on the diagrams are approximate and used only for drafting purposes: Q ≈ 7.5 e ; R ≈ D I /2 + 16 e . Dimension D M = D I + 2 e . Pressure angle B max is approximately 344 e / D M degrees for three sides, and 299 e / D M degrees for four sides. Tolerances: ISO H7 tolerances apply to bore dimensions. For shafts, g6 tolerances apply for sliding fits; k7 tolerances for tight fits. Choosing Between Three- and Four-Sided Designs: Three-sided designs are best for applications in which no relative movement between mating components is allowed while torque is transmitted. If a hub is to slide on a shaft while under torque, four-sided designs, which have larger pressure angles B max than those of three-sided designs, are better suited to sliding even though the axial force needed to move the sliding member is approximately 50 percent greater than for comparable involute spline connections.
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