Chamberlain 7220 1/2HP - Manual (Page 9)

9
ASSEMBLY STEP 2
Install the Trolley
• Attach the trolley threaded shaft to the trolley with
the lock washer and nuts as shown.
• As a temporary stop, insert a screwdriver into the
hole in the front end of the T-rail.
• Slide the trolley assembly along the rail to the
screwdriver stop.
NOTE: If trolley hits against any nuts on the T-rail,
the bolts and nuts were attached from the wrong
side and must be repositioned. Review Assembly
Step 1.
Temporary Stop
Screwdriver
Trolley
Threaded
Shaft
Inner Nut
5/16" Lock
Washer
5/16"
Outer Nut
5/16"
Trolley
ASSEMBLY STEP 3
Fasten the T-Rail to the Motor Unit
• Place the opener on packing material to protect
the cover. For convenience, put a support under
the cable pulley bracket.
• Remove the two 5/16"-18x1/2" washered screws
mounted in the top of the motor unit.
• Align the holes in the back section of the T-rail with
the holes in the motor unit.
• Fasten the rail with the two washered screws
previously removed. Tighten securely. Remember
to use only these screws! Any other screws
will cause serious damage to the opener.
• Insert a 5/16"-18x7/8" hex screw into the cover
protection bolt hole in the T-rail as shown. Tighten
securely with a 5/16" lock washer and nut.
NOTE: This screw prevents trolley over-travel. Keep
a 2" minimum between the trolley and this screw
when adjusting travel limits (see page 28).
Washered Screw
5/16"-18x1/2"
USE ONLY THIS
TYPE AND SIZE
SCREW
T-Rail
(Back Section)
Cover
Protection
Bolt Hole
Nut
5/16"-18
Hex Screw
5/16"-18x7/8"
Lock Washer
5/16"-18
Nut
5/16"-18 Lock Washer
5/16" Hex Screw
5/16"-18x7/8"
HARDWARE SHOWN ACTUAL SIZE
To avoid serious damage to opener, ONLY use screws
mounted in top of motor unit.
CAUTION
Lock Washer
5/16" Nut
5/16" -18
HARDWARE SHOWN ACTUAL SIZE