Chamberlain 585 3-4 hp Manuel D’Utilisation

To avoid SERIOUS damage to opener, ONLY use
bolts/fasteners mounted in top of motor unit.

• Remove the bolt and lock nut from the top of the

motor unit.

• Place rail onto the bolt mounted on the motor unit

and align the back hole with the hole in the top of
the unit.

• Fasten rail with the washered bolt and lock nut

previously removed. Tighten securely. Remember
to use only these bolts/fasteners! Any other
bolts/fasteners will cause serious damage to
the opener.

• Cut tape from rail, belt and styrofoam.

• REMOVE STYROFOAM.

• Position belt over the motor unit sprocket.

Motor unit
Sprocket

Washered Bolt 
5/16"-18x1/2"

Styrofoam

Rail
Hole

Lock Nut

6

• By hand, thread the spring trolley nut on the

threaded shaft until it is finger tight against the
trolley (Figure 1). Do not use any tools. 

• Insert a screwdriver tip into one of the nut ring

slots and brace it firmly against the trolley
(Figure 2).

• Place a 7/16" open end wrench on the square

end. Rotate about 1/4 turn until the spring releases
and snaps the nut ring against the trolley
(Figure 3).

This extends the spring for optimum belt tension.

Trolley
Threaded
Shaft

Spring/Trolley Nut

Nut
Ring

Trolley
Threaded 
Shaft

Nut Ring
Slots

Square 
End

Nut Ring

Trolley

Nut Ring

Trolley