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4.4 Efficiency Calculation SHG-2UH
The efficiency of Harmonic Drive® Gears varies depending on the following conditions
• Ratio
• Input speed
• Load torque
• Temperature
• Lubrication condition (type of lubricant and the quantity)
The efficiency curves are valid for gears operating at rated output torque. The efficiency of a gear operating at a load below
the rated torque may be estimated using a compensation curve and equation as shown on the next page. The efficiency of the
Simplicity Units SHG-2SO and SHG-2SH strongly depends on the integration into the application, like sealing concept, bearing
concept etc. Please contact the Harmonic Drive AG for further support.
4.4.1
Efficiency Calculation Scheme
Table 36.1
Calculation Procedure
The efficiency may be determined
using the efficiency graphs.
Calculate
the torque factor V.
T
av
V =
T
N
With:
T
= Average torque
av
T
= Rated torque at rated speed
N
Determination of the correction factor K
depending on the gear type and the torque factor V,
see example in illustration 38.2.
Determination of correction value η
see illustration 38.3
Calculation of the total efficiency η
= K • (η
+ η
)
η
L
R
e
36
[Equation 36.2]
,
e
L
[Equation 36.3]
Example
Efficiency of SHG-20-80-2UH with
input speed n = 1000 rpm
output torque T = 35 Nm at 20 °C ambient temperature.
Lubrication: Harmonic Drive ® Grease
See illustration 38.4
= 63 %
η
R
35 Nm
V =
= 0.8
44 Nm
T
= 35 Nm
av
T
= 44 Nm
N
K = 0.9
= -6.6 %
η
e
= 0.9 · (62 % - 6.6 %) = 50 %
η
L
1021387
12/2018
V02
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