Chamberlain 248735S 3/4 HP User Manual

5

•  Generally, a one-piece door does not require 

reinforcement. If your door is lightweight, refer to the 
information relating to sectional doors in Installation 
Step 11.

•  Depending on your door’s construction, you may need 

additional mounting hardware for the door bracket 
(Step 11).

Without a properly working safety reversal system, 
persons (particularly small children) could be 
SERIOUSLY INJURED or KILLED by a closing garage 
door.
•  The gap between the bottom of the garage door 

and the fl oor MUST NOT exceed 1/4" (6 mm). 
Otherwise, the safety reversal system may NOT 
work properly.

•  The fl oor or the garage door MUST be repaired to 

eliminate the gap.

FINISHED CEILING

Support bracket & fastening 
hardware is required.
See page 15.

Wall-mounted 
Door Control

Motor Unit

Access 
Door

Gap between fl oor and 
bottom of door must not exceed 1/4" (6 mm).

Gap between fl oor and 
bottom of door must 
not exceed 1/4" (6 mm).

Safety 
Reversing Sensor

Safety 
Reversing Sensor

Safety 
Reversing Sensor

Safety Reversing 
Sensor

Header Wall

Rail

Slack in chain tension 
is normal when garage 
door is closed.

Emergency 
Release 
Rope & 
Handle

Emergency 
Release 
Rope & 
Handle

Header 
Bracket

Header 
Bracket

Straight Door 
Arm

Straight Door 
Arm

Curved 
Door 
Arm

Curved 
Door Arm

Garage Door

Garage 
Door

Door Bracket

Door 
Bracket

Header 
Wall

Header 
Wall

Cable

Cable

Rail

Rail

Trolley 
Stop Bolt

Trolley 
Stop Bolt

Trolley

Chain