Surface Strength Of Bevel Gears0 pages

17.3.4 Examples of Bevel Gear Bending Strength
Calculations
Table 17-24A Gleason Straight Bevel Gear Design Details
No. Item Symbol Unit Pinion Gear
1 Shaft Angle S degree 90º
2 Module m mm 2
3 Pressure Angle a
degree
20º
4 Central Spiral Angle bm 0º
5 Number Of Teeth z 20 40
6 Pitch Circle Diameter d mm 40.000 80.000
7 Pitch Cone Angle d degree 26.56505º 63.43495º
8 Cone Distance Re
mm
44.721
9 Tooth Width b 15
10 Central Pitch Circle Diameter dm 33.292 66.584
11 Precision Grade
JIS 3 JIS 3
12 Manufacturing Method Gleason No. 104
13 Surface Roughness 12.5 mm 12.5 mm
14 Revolutions per Minute n rpm 1500 750
15 Linear Speed v m/s 3.142
16 Direction of Load Unidirectional
17 Duty Cycle Cycle More than 107 Cycles
18 Material
SCM 415
19 Heat Treatment Carburized
20 Surface Hardness HV 600 ... 640
21 Core Hardness HB 260 ... 280
22 Effective Carburized Depth mm 0.3 ... 0.5
Table 17-24B Bending Strength Factors for Gleason Straight Bevel Gear
No. Item Symbol Unit Pinion Gear
1 Central Spiral Angle bm degree 0º
2 Allowable Bending Stress at Root sFlim kgf/mm² 42.5 42.5
3 Module m
mm
2
4 Tooth Width b 15
5 Cone Distance Re 44.721
6 Tooth Profile Factor YF
2.369 2.387
7 Load Distribution Factor Ye 0.613
8 Spiral Angle Factor Yb 1.0
9 Cutter Diameter Effect Factor YC 1.15
10 Life Factor KL 1.0
11 Dimension Factor KFX 1.0
12 Tooth Flank Load Distribution Factor KM 1.8 1.8
13 Dynamic Load Factor KV 1.4
14 Overload Factor KO 1.0
15 Reliability Factor KR 1.2
16 Allowable Tangential Force at Central Pitch Circle Ftlim kgf 178.6 177.3
17.4 Surface Strength Of Bevel Gears
This information is valid for bevel gears which are used in
power transmission in general industrial machines. The
applicable ranges are:
Radial Module:
Pitch Diameter:
Linear Speed:
Rotating Speed:
md
v
n
1.5 to 25mm
Straight bevel gear under 1600
mm
Spiral bevel gear under 1000
mm
less than 25 m/sec
less than 3600 rpm
17.4.1 Basic Conversion Formulas
The same formulas of SECTION 17.3 apply. (See page 84).
17.4.2 Surface Strength Equations
In order to obtain a proper surface strength, the tangential
force at the central pitch circle, Ftm, must remain below the
allowable tangential force at the central pitch circle, Ftmlim,
based on the allowable Hertz stress sHlim.
Ftm £ Ftmlim (17-37)
Alternately, the Hertz stress sH, which is derived from the
tangential force at the central pitch circle must be smaller than
the allowable Hertz stress sHlim.
sH £ sHlim (17-38)
The allowable tangential force at the central pitch circle,
Ftmlim, in kgf can be calculated from Equation (17-39).
(17-39)
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