Connect Door Arm To Trolley (Sectional Door); Connect Door Arm To Trolley (One-Piece Door) - Chamberlain 1255GM Owner's Manual

Installation Step 12
Connect Door Arm to Trolley
Follow instructions which apply to your door type
as illustrated below and on page 23.
Make sure garage door is fully closed. Pull the manual release handle to disconnect the outer trolley
from the inner trolley. Slide the outer trolley back (away from the door) about 2" as shown in
Figures 1, 2 and 3.
Figure 1:
• Fasten straight door arm section to outer trolley
with a clevis pin. Secure the connection with a
ring fastener.
• Fasten curved section to the door bracket in the
same way as shown.
Outer Trolley
Ring
Fastener
Door
Bracket
Clevis Pin
Figure 3:
• If holes in curved arm are above holes in straight
arm, disconnect straight arm. Cut about 6" from
the solid end. Reconnect to trolley with cut end
down as shown.
• Bring arm sections together.
• Find two pairs of holes that line up and join with
screws, lock washers and nuts.
Hardware Shown Actual Size
Nut 5/16"-18 Lock Washer 5/16"
Hex Screw
5/16"- 18x7/8"
Proceed to Adjustment Step 1, page 24. Trolley will re-engage automatically when the opener is operated.
SECTIONAL Doors Only
Inner Trolley
Clevis
Pin
Straight
Door Arm
Curved
Figure 1
Door Arm
Hole Alignment Alternative
Ring Fastener
Clevis Pin
5/16"x1"
Figure 2:
• Bring arm sections together. Find two pairs of holes
that line up and join sections. Select holes as far
apart as possible to increase door arm rigidity.
Nuts
5/16"-18
Door Bracket
Nuts
5/16"-18
22
Lock
Washers
5/16"
Screws
5/16"-18x7/8"
Figure 2
Lock
Washers
5/16"
Screws
5/16"-18x7/8"
Cut This End
Figure 3
Rope
Manual
Release
Handle