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4.4 Efficiency Versus Load
Efficiency for Harmonic Drive® Gears varies depending on the output torque. The efficiency curves are for gears operating at
rated output torque. Efficiency for 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.
4.4.1 Efficiency Calculations
Table 25.1
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
K depending on gear type and V,
see illustration 25.4
Efficiency
= η . K
η
L
Calculating Factor K
Illustration 25.4
K
1019658
11/2014
[Equation 25.2]
[Equation 25.3]
Example
Efficiency of HFUC-20-80-2A-GR with
input speed n=1000 rpm
output torque T=19.6 Nm at 20° C ambient temperature.
Lubrication: Oil
From matching chart
η = 78 %
T
= 19.6 Nm
av
T
= 34.0 Nm
N
19.6 Nm
V =
= 0.57
34.0 Nm
1.0
K
0.8
0.6
0.4
0.2
0
0.2 0.4 0.6 0.8
1.0
V
= 78 . 0.93 = 73 %
η
L
25
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