Chamberlain 3255-2M 1/2 HP Manuale Utente

Lock
Washer

Inner Nut

Trolley

Chain

Base of Rail

1/2" (13 mm)

Outer Nut

Mid Length of Rail

To Tighten Outer Nut

To Tighten Inner Nut

INSTALLATION

ASSEMBLY STEP 3

Tighten the Chain

• Spin the inner nut and lock washer down the trolley

threaded shaft, away from the trolley.

• To tighten the chain, turn outer nut in the direction

shown (Figure 1).

• When the chain is approximately 1/2" (13 mm) above

the base of the rail at its midpoint, re-tighten the inner

nut to secure the adjustment.

Sprocket noise can result if chain is too loose.
When installation is complete, you may notice some chain

droop with the door closed. This is normal. If the chain

returns to the position shown in Figure 2 when the door is

open, do not re-adjust the chain.
NOTE: During future maintenance, ALWAYS pull the

emergency release handle to disconnect trolley before

adjusting chain. You may notice loosening of chain after

Adjustment Step 3 (Test the Safety Reversal System).

Check for proper tension and readjust chain if necessary.

Then repeat Adjustment Step 3.
You have now finished assembling your garage door

opener. Please read the following warnings before

proceeding to the installation section.

IMPORTANT INSTALLATION INSTRUCTIONS

To reduce the risk of SEVERE INJURY or DEATH:

WARNING

1. READ AND FOLLOW ALL INSTALLATION WARNINGS AND

INSTRUCTIONS.

2. Install garage door opener ONLY on properly balanced and

lubricated garage door. An improperly balanced door may
NOT reverse when required and could result in SEVERE
INJURY or DEATH.

3. ALL repairs to cables, spring assemblies and other hardware

MUST be made by a trained door systems technician BEFORE
installing opener.

4. Disable ALL locks and remove ALL ropes connected to garage

door BEFORE installing opener to avoid entanglement.

5. Install garage door opener 7 feet (2.13 m) or more above

floor.

6. Mount emergency release handle 6 feet (1.83 m) above floor.
7. NEVER connect garage door opener to power source until

instructed to do so.

8. NEVER wear watches, rings or loose clothing while installing

or servicing opener. They could be caught in garage door or
opener mechanisms.

9. Install wall-mounted garage door control:

• within sight of the garage door.

• out of reach of children at minimum height of

5 feet (1.5 m).

• away from ALL moving parts of the door.

10. Place entrapment warning label on wall next to garage door

control.

11. Place manual release/safety reverse test label in plain view

on inside of garage door.

12. Upon completion of installation, test safety reversal system.

Door MUST reverse on contact with a 1-1/2" (3.8 cm) high
object (or a 2x4 laid flat) on the floor.

Figure 1

Figure 2