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RCA L Version 2.0 20
5.6 Drive Chain Tension
Figure 11 is a finished header assembly that has been installed. Also note the idler barrel
has been bolted back into place back.
Chain tension should be checked after the door is cycled a few times.
The M&I drive chain is to be tensioned so the deflection of the slack side (bottom side) of the
chain is equal to 2% of the distance between the shafts. For door over 12’ x 12’ this value is
3/8” (9.5 mm). For doors under 12’ x 12’ this value is
9/32” (7.1 mm).
5.6.1 Operator assembly
The operator is not assembled to the door when it is
shipped. On the drive side of the header assembly, 4
weld studs serve as attachment points for the operator.
When assembling the operator, the slots on the
operator mounting surface should be centered on the
studs Tighten using the provided flat washers and nuts.
Assemble the chain.
5.6.2 Chain Tension Adjustment
If the Chain tension needs to be adjusted, you need to
do the following:
Support the operator prior to loosening the operator
mounting bolts.
Loosen the 4 bolts that attach the operator to the
header assembly.
Either raise or lower the operator to achieve the proper
tension.
Retighten the 4 bolts that attach the operator to the
header assembly.
Installation
Slack side
Figure 12b
Figure 12a