Craftsman 139.18867 Owner's Manual page 9

Assembly Step 1
Assemble the Rail
The Chamberlain Group, Inc.
Screw Drive LM
3-Piece Rail
4. Beginning with the sprocket end, straighten the two
Align Rails & Attach Support Brackets
rail sections so that the screw rod is in a straight line at
the joint. (Avoid handling the joints, which may have
8/7/94 - 8/10/94 - 9/12/94 - 1/12/95
sharp edges.)
5. Carefully slide the pins at the top edge of the rail into
the openings on the adjacent rail. It is essential that
the rail assembly be on a level surface to achieve
proper alignment and to avoid damage to the pins.
6. Insert two 1/4"-20x1-3/4" bolts through the center
holes of a brace, and place its open length against the
rail at this joint, aligning the holes as shown. Position
another brace on the opposite side of the rail over the
bolts, add 1/4"-20 lock nuts, and hand tighten. Insert
two additional bolts and hand tighten.
Lock
Nuts
Door End
1/4" - 20 x 5/8"
Hex Screw
Hardware Shown Actual Size
Bolt
1/4-20x1-3/4" (8)
(Continued)
Lock
Nuts
Rail
Support
Brace
Rail Pin
Alignment
Hole
1/4" - 20
Slide End
Lock Nut
Rails Towards
Center Rail
1/4"-20
Lock Nut
7. Keeping the rail straight and on a level surface, grasp
the screw rods on each side of the remaining joint and
pivot into a straight line. Repeat steps 5 and 6.
8. With a 7/16 wrench, tighten bolts til snug, working
from the center holes of the braces to those further
from the joints. Do not overtighten.
Rail
Support
Brace
Alignment
Hole
Rail Pin
Center Rail
Center
Rail
1/4x20x1-3/4"
Bolts
Hex Screw
Nut 5/16"-18
5/16"-18 x 7/8"
9
Sprocket End
Slide End
Rails Towards
Center Rail
1/4x20x1-3/4"
Bolts
End
Alignment
Rail
Hole
Rail Pin
Lock Washer 5/16"