Appendix
pro.Bose.com
Page 22 Installation and Safety Guidelines
The following general equation can be used to calculate the moment (rotational) force about point M (front fastener):
∑
M
1
= (F1 * X
1
) - (F
COG
* X
COG
)
To calculate the load applied to the rear fastener of the top module side in the above diagram, the above equation must be solved for
the F1 value. For the load to be fully supported by the rear fastener, the moment force about M1 will be 0, with the force of F1 being
equal but opposite the FCOG force. Thus, the equation becomes:
0 = (F
1
* X
1
) - (F
COG
* X
COG
) where F
COG
= (1/2) * W
A
(as each side supports half the total)
0 = F
1
*15 - (283.5 / 2) * (28.75)
Solving for F
1
: F
1
= ((283.5 / 2) * (28.75)) / 15
= 271. 68 kg
Step 3. Compare F
M
to WLL. Compare the results for F
M
to the per point WLL given for the array element. The calculated value of 271.68
kg is less than the per-point WLL of 412 kg. Therefore, the array design is within load limits.
The above example illustrates a very simple case. Additional elements, combinations of elements, and positive or negative pitch of the
array frame will significantly complicate the calculations. It is recommended that the designer choosing to use this method review the
results with a licensed professional engineer.
Center of Gravity Dimension Frame of Reference
Pick Up
Position
Frame Pitch
Total
Array
Height
Y
COG
X
COG
