Chamberlain C2405C Manuel D'installation page 11

Assembly
STEP 5 Tighten the Chain
1. Spin the inner nut and lock washer down the trolley threaded shaft, away from the trolley.
2. To tighten the chain, turn the outer nut in the direction shown.
3. When the chain is approximately 1/4" (6 mm) above the base of the rail at it's midpoint,
retighten the inner nut to secure the adjustment.
Sprocket noise can result if the chain is too loose. When installation is complete, you may no-
tice some chain droop with the door closed. This is normal. If the chain returns to the position
shown when the door is open, do not re-adjust the chain.
NOTE: During future maintenance, ALWAYS pull the emergency release handle to disconnect the trolley
before adjusting the chain.
To Tighten Outer Nut
Chain
Base of Rail
Outer Lock
Trolley
Nut Washer
Threaded
Shaft
Inner Nut
To Tighten
Inner Nut
1/4" (6 mm)
Mid length of Rail
11