Chamberlain 120ad Garage Door Opener User Manual


 
9
ASSEMBLY STEP 3
Attach Chain Spreader
Attach chain spreader to opener with phillips pan
head screws.
Chain Spreader
P
hillips Pan Head Screws
Opener
To avoid serious damage to opener, ONLY use screws
mounted in top of motor unit.
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ATTENTIONATTENTION
AVERTISSEMENTAVERTISSEMENT
ASSEMBLY STEP 2
Attach Trolley to Rail
Slide outer trolley into rail assembly, be sure arrow
on trolley is heading in direction of door is heading in
direction of door. Slide outer trolley down rail until it
engages with inner trolley.
114A2845
Outer Trolley
Arrow
Arrow
Rail Assembly
Tow
ards Door
ASSEMBLY STEP 4
Fasten Rail to Opener & Install Chain
Remove four washered bolts from top of opener. Place
rail on opener, flush with stops on top of opener. Wrap
chain around slot in spreader and over sprocket. Push
idler pulley bracket assembly toward front of the rail to
eliminate excess slack in chain. Align bolt holes on
brackets with bolt holes on opener
. Secure brackets to
opener with previously removed bolts . Tighten bolts
securely.
The opener sprocket teeth must engage
the chain. Insert bolt into trolley stop bolt hole secure
with lock washer and nut.
CAUTION: Use only those bolts mounted in the
top of opener
. Use of any other bolts will cause
serious damage to opener
.
Set Chain Tension
Thread spring nut on carriage bolt unit finger tight.
Insert a screwdriver tip into one of the slots of the nut
ring and brace it firmly against the header sleeve.
Place an open end wrench on the square end of the
spring nut, slightly rotate nut about 1/4 turn clockwise
until nut ring is released against header sleeve. This
sets spring to optimum chain tension. chain may slip
off sprocket if chain is too loose. If chain does slip re-
tighten spring nut by turing nut clockwise 1/2 turn.
Do NOT overtighten chain.
To avoid possible SERIOUS INJURY to fingers from
moving garage door opener:
• ALWAYS keep hand clear of sprocket while operating
opener.
• Securely attach chain spreader before operating.
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CAUTIONCAUTION
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