User Guide

20 Installation
Doc 01-G0547
Rev D
Step 4: Drive Chain
1 If you have not already done so, remove the
operator cover.
2 Locate and engage the manual disconnect
lever and lock it in place. Refer to 14.
3 Connect one chain take-up bolt to the end of
the chain and attach to the rear gate bracket.
Refer to bracket detail below.
4 Ensure that the drive and idler sprockets are
in-line with each other. Thread the chain
through plastic chain guide, around drive and
idler sprockets, and then through the second
plastic chain guide toward front gate bracket.
CAUTION
When pulling the chain through the operator,
the limit shaft will turn. Do not drive the limit
(nuts) actuators on this shaft past their
normal positions.
5 Adjust the chain to proper length and attach
second take-up bolt to chain end. Secure the
take-up bolt to the front gate bracket as
shown.
Important: Check alignment of gate brackets
to idler sprockets in both vertical and
horizontal directions.
◊
Gate brackets must be level and in line
with bottom of idler sprockets.
◊
◊
01-G0547F18
Figure 16
SAFETY BRACKET
INSERT CHAIN THROUGH PLASTIC GUIDES
01-G0547F19
Figure 17
6 Adjust nuts on chain take-up bolts to remove chain slack. Leave a maximum of one (1) inch
of chain slack for every 10 feet of chain length. Do not overtighten chain.
7 It is recommended that the gate brackets be welded to the gate after the chain is properly
installed, adjusted, and the operator is functioning.
SUGGESTION
To prevent excessive chain sag, LiftMaster recommends that you add some type of chain support
for gates over 20 feet in length. Please note that chain supports must be located a minimum of ¾”
below the idler sprocket shield and must note exceed ¾” beyond the centerline of the chain.
NOTE ABOUT SOME TYPES OF CANTILEVER GATES
With some cantilever gates over 20 feet long, you may need to add a brace along the length of the
gate to prevent the gate from bowing with chain is tightened. This may also be required on some
styles of gates that are constructed out of aluminum. Note that if positioned properly, this brace
can also be used as a chain support.