Automatic Systems BL 229 - Balancing of the Boom Arm by Means of the Spring

7.2. BALANCING OF THE BOOM ARM BY MEANS OF THE SPRING
The tension of the spring must be adjusted in such a way as to ensure minimal effort for the motor both at the opening and the
closing of the barrier:
1. Withdraw screw (1) and disconnect the connecting rod from its lever.
2. Raise the arm slightly and release it: it must remain in balance.
Repeat the operation at various different angles.
3. If the arm drops, the tension of the spring must be increased:
• Loosen locknut (2).
• Tighten nut (4) slightly against support (3) to increase the spring’s tension.
Repeat until stage 2 is correct.
• Tighten nut (2) to lock nut (4).
• If it is insufficient, position the spring on the next mark (5) further from the arm shaft (e.g. B  C).
• If that is still insufficient, use two springs and repeat the above adjustments.
4. If the arm goes up, the tension of the spring must be decreased:
• Loosen locknut (2).
• Loosen nut (4) slightly to slacken the spring.
Repeat until stage 2 is correct.
• Tighten nut (2) to block nut (4).
• If it is not sufficient, position the spring on the previous reference mark (5) closer from the arm shaft (e.g. B  A).
• f that is still insufficient, remove one spring (if there were two of them) and repeat the above adjustments.
X
1
5
4 2 3
5
Fig. 26 - Detail of fixing points on the spring jaw
Fig. 27 - Balancing spring(s) settings
The following table shows the spring adjustments for the various arm lengths.
29
BL 229