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Torsional stiffness
(Harmonic Drive® Gears) K
3
[Nm/rad]
The amount of elastic rotation at the output for a given
torque and the Wave Generator blocked. The torsional
stiffness K
3
describes the stiffness above a defined reference
torque where the stiffness is almost linear. Values below
this torque can be requested or found on our web site.
The value given for the torsional stiffness K
3
is an aver-
age that has been determined during numerous tests. The
limit torques T
1
and T
2
and calculation example for the total
torsional angle Gesamtverdrehwinkels can be found in the
secondary technical documentation.
Torsional stiffness
(Harmonic Planetary gears) K [Nm/rad]
The amount of elastic rotation at the output for a given
torque and blocked input shaft. The torsional rigidity of the
Harmonic Planetary gear describes the rotation of the gear
above a reference torque of 15% of the rated torque. In this
area the torsional stiffness is almost linear.
Transmission accuracy [arcmin]
The transmission accuracy of the gear represents a linearity
error between input and output angle. The transmission ac-
curacy is measured for one complete output revolution using
a high resolution measurement system. The measurements
are carried out without direction reversal. The transmission
accuracy is defined as the sum of the maximum positive and
negative differences between theoretical and actual output
rotation angle.
Weight m [kg]
The weight specified in the catalog is the net weight without packing and only applies to standard versions.
K
1
K
2
K
3
0
T
2
Torsion
φ
φ
2
φ
1
T
1
Torque T
K
1
, K
2
, K
3
= Torsional stiffness, w = Output angle
φ
1 = Torsion angle, with output torque T
1
φ
2 = Torsion angle, with output torque T
2
T
N
= Rated torque
φ
= Output angle
A
ccur
ac
y
Tr
ansmission
accur
ac
y
360° Output
angle
