Chamberlain Merlin MJ3800R Installation And Operating Instructions Manual page 8

INSTALLATION STEP 2
EASY-FIT SPROCKET INSTALLATION
1. Identify matching hole patterns in drum wheel and base
plate, then fasten the 3 x 3/8" hex bolts to the
corresponding holes in the drum wheel using the large flat
washers and spring washers as shown in figure 1. Ensure
that the 3/8" hex nuts are fastened tightly.
2. Place large flat washers on the protruding bolts and
fasten base plate to the bolts using large flat washers,
spring washers, and 3/8" hex nuts as shown in figure 2.
When selecting the orientation of the base plate in relation
to the drum wheel ensure there is enough clearance
between the slots for the drive spacer and the spokes of
the drum wheel.
3. Slide sprocket incl. half bush over door shaft and insert
bush retainer incl. half bush and fasten to sprocket using
M8 bolts and M8 Nyloc nuts as shown in figure 3. Ensure
nuts are firmly tightened.
4. Attach to sprocket using M8 x 16 Hex bolt and spring
washer as shown in figure 4.
Drum wheel
Base plate
Base Plate
Bush retainer
Bush retainer
8
Drum Wheel
Half bush-2
Half bush - 2
Half bush-1
Half bush - 1
figure 1
figure 2
figure 3
figure 4