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4.11 Axial Forces at the Wave Generator SHG-2SO and SHG-2SH
When a Harmonic Drive® Gear is used as a speed reducer (input via Wave Generator), the deflection of the Flexspline leads to
an axial force acting on the Wave Generator. This axial force acts in the direction of the Flexspline diaphragm.
When the Harmonic Drive® Component Set is used as a speed accelerating gear (reverse operation, e.g. when braking), the
axial force acts in the opposite direction. In any case the axial force must be supported by the input shaft (motor shaft).
The Wave Generator thus needs to be fixed on the input shaft in the axial direction. In closed Harmonic Drive® Units
and gearboxes with support bearings the axial force is absorbed internally.
Illustration 49.1
Speed reducer
Table 49.2
Ratio
30
50
80 ... 160
with:
F
= Axial force [N]
AX
D
= (Size) · 0.00254 [m]
T
= Torque at the output [Nm]
µ
= 0.07, Coefficient of friction
2µPF = Additional force (only CSD and SHD) [N]
Example
Size 32 (CSD-32-50)
Output torque = 200 Nm
Coefficient of friction µ = 0.07
200 Nm
F
= 2 · (32 · 0.00254) m · 0.07 · tan 30° + 16 N
AX
F
= 215 N
AX
Table 49.6
2µPF for CSD and SHD
1021387
12/2018
V02
Reverse
operation
T _
F
= 2 ·
· µ · tan 32°
AX
D
T _
F
= 2 ·
· µ · tan 30° + 2µPF
AX
D
T _
F
= 2 ·
· µ · tan 20° + 2µPF
AX
D
Unit
14
17
[N]
2.1
4.1
20
25
32
5.6
9.8
16
[Equation 49.3]
[Equation 49.4]
[Equation 49.5]
40
50
24
39
49
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