Bearings - Harmonic Drive SHG Series Manual

3.3.6 Bearings

Output Bearing
SHG Units incorporate a high stiffness cross roller bearing to support output loads. This specially developed bearing can
withstand high axial and radial forces as well as high tilting moments. The reduction gear is thus protected from external
loads, so guaranteeing a long life and constant performance. The integration of an output bearing also serves to reduce subse-
quent design and production cost, by removing the need for additional output bearings in many applications. However, in some
applications the machine element to be driven requires additional bearing support. In this case, please take care to avoid
overdetermination of the bearing arrangement. The cross roller bearing of the unit should be used as the fixed bearing,
whilst the additional support bearing should be floating, if possible. Table 23.1 lists ratings and important dimensions for the
output bearings.
Table 23.1
Symbol
Bearing type
1)
Pitch circle ø
d
Offset 2)
Dynamic load rating
Static load rating
Permissible dynamic
M [Nm]
tilting moment 3)
Permissible static
M
tilting moment
4)
Tilting moment
K [Nm/arcmin]
stiffness 6) B
Permissible axial
load 5)
Permissible radial
load
5)
Normally, the gear life is determined by the life of the Wave Generator bearing. Depending on the specific load conditions the output bearing can also be determinant for the unit
life.
1) F = Four-point bearing, C = Cross roller bearing
See illustration 23.2
2)
These values are valid for moving gears. They are not based on the equation for lifetime calculation of the output bearing but on the maximum allowable deflection of the
3)
Harmonic Drive® Component set. The values indicated in the table must not be exceeded even if the lifetime equation of the bearing permits higher values.
These values are valid for gears at a standstill and for a static load safety factor f
4)
chapter 4.7.
These data are valid for f = 1.3, n = 15 rpm and L
5)
w
These data are only valid if the following conditions are fulfilled:
3) 4) 5)
For: M, M : F = 0, F = 0 | F : M = 0; F
0 a r a
Average value
6)
1021387 12/2018 V02
SHG-14 SHG-17
[Unit]
C C
[m] 0.050 0.060
p
R [m] 0.022 0.024
C [N] 5800 10400
C [N] 8600 16300
0
74 124
[Nm] 144 328
0
25 45
F [N] 3050 5469
a
F [N] 2044 3664
r
= 15000 h
10
= 0 | F : M = 0, F = 0
r r a
SHG-20 SHG-25 SHG-32 SHG-40
C C C
0.070 0.085 0.111
0.026 0.030 0.036
14600 21800 38200 43300
22000 35800 65400 81600
187 258 580
515 1070 2425
73 114 291
7678 11464 20088
5144 7681 13459
= 1.8 for sizes 14 ... 20 and 1,5 for sizes 25 ... 58. For other values of f
s
Illustration 23.2
SHG-45 SHG-50 SHG-58
C C C
0.133 0.154 0.170 0.195
0.044 0.048 0.053 0.062
77600 81600 87400
135000 149000 171000
849 1127 1487 2180
3623 6949 8505 11159
521 748 1021
22770 40808 42911 45961
15256 27341 28751 30794
, please refer to
s
SHG- 65
C C
0.218
0.072
130000
223000
2740
16200
1545 2155
68364
45804
23