Assembly Section: Pages; Fasten T-Rail To Opener; Tighten The Belt - Chamberlain 1280 Owner's Manual

ASSEMBLY STEP 1
Attach the T-Rail To the Opener
The Chamberlain Group, Inc.
Liftmaster Synchro Drive
Spring Trolley Nut Assembly
3/5/92 - 5/16 /92 - 5/21/92 - 6/2/92
• Remove the two washered screws mounted in top
of opener. 6/11/92
• Align T-rail and styrofoam over opener sprocket.
• Cut tape from T-rail, belt and styrofoam.
• REMOVE STYROFOAM.
• Insert both washered screws through the T-rail
into the opener. Tighten both screws securely .
USE ONLY THESE SCREWS! Any other screws
will cause serious damage to the opener.
Group, Inc.
o Drive
Position belt over the opener sprocket.
t Assembly
- 5/21/92 - 6/2/92
ASSEMBLY STEP 2
Set the Belt Tension
Figure A
• By hand, thread the spring trolley nut on the
threaded shaft until it is finger tight against the
trolley (Figure A). Do not use any tools.
• Insert a screwdriver tip into one of the nut ring
slots and brace it firmly against the trolley
(Figure B).
TYPE AND SIZE
SCREW

Assembly Section: Pages 6 - 7

Trolley
Trolley
Threaded
Shaft
Spring
Trolley Nut
The Chamberlain Group, Inc.
Spring Trolley Nut
1/25/96
To fasten rail, use only those screws mounted
in the top of the opener. Any other screws will
cause serious damage to the opener.
Washered Screw
5/16"-18x1/2"
Belt
USE ONLY THIS
TYPE AND SIZE
SCREW
Washered Screw
T-Rail
Belt
Figure B
Square End
Trolley
• Place a 7/16" open end wrench on the square
end. Rotate about 1/4 turn until the spring releases
and snaps the nut ring against the trolley (Figure C).
This extends the spring for optimum belt tension.
Figure C
Trolley Nut Ring
BEFORE
1"
6
CAUTION
Styrofoam
T-Rail
Hole
5/16"-18x1/2"
Opener
Sprocket
Hole
T-Rail
Hole
Trolley
Threaded
Shaft
Nut
Ring
Nut Ring
Slots
Trolley
Nut Ring
AFTER RELEASE
1-1/4"