HarmonicDrive SHA - Y series, Manual, Page: 73 / 103

2-4 Examining operating status
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Load torque calculation
Calculate the load torque as follows:

Rotary motion
The rotary torque for the rotating mass W on the ring
of radius r from the center of rotation is shown in the
figure to the right.
T : Rotary torque (Nm)
μ
: Friction coefficient
W : Mass (kg)
r : Average radius of friction side (m)
The right graph gives a calculation example
when the friction coefficient μ is assumed as 0.1
and the horizontal axis and vertical axis
represent mass and rotational radius of friction
side, respectively. The actuator toque value
shown in the graph indicates 20% of the
maximum torque.

Linear operation (horizontal operation)
The rotary torque when the mass W moves horizontally due to the screw of pitch P is shown below.
T : Rotary torque (Nm)
μ
: friction coefficient
W : mass (kg)
P : Screw feed pitch (m)

Linear operation (vertical operation)
The rotary torque when the mass W moves vertically due to the screw of pitch P is shown below.
Mass: W
Pitch: P
Friction: μ
π ×
× × µ × =
2
P
W 8 . 9 T
π ×
× × =
2
P
W 8 . 9 T
Pitch: P
Mass: W
r W 8 . 9 T
× × µ × =
Radius: r
Mass: W
Friction: μ
Example of rotary torque calculation (friction coefficient = 0.1)
SHA-Y: 20% torque of maximum torque is shown.
Mass W (kg)
R
adi
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ti
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m
m
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10
1000 3000
100
10
100
1000
10000
15 Nm
20 Nm
SHA25Y51
SHA65Y81
SHA40Y51
SHA32Y51
30 Nm
40 Nm
50 Nm
200 Nm
300 Nm
10 Nm
500 Nm
600 Nm
700 Nm
800 Nm
5 Nm