LiftMaster 3950 3950 Addendum Manual - Page 2

LIVE SHAFT REQUIREMENTS Live Shaft doors are automated by the Model 3950 driving a chain which spans the drive sprocket and the door sprocket. The door sprocket is attached to the door axle which spins the drums and rolls the door curtain. The assembly is held up by door brackets and the door guides. (Figure 2) Axle Drum Wall Drum Bracket Door Guide Figure 2 - Live Shaft Components Minimum Side Room The minimum amount of side room depends on the mounting option for the Model 3950. For a standard wall mount or outside bracket mount using the optional mounting bracket Model 3950MB, a minimum of 11" is required to the outside of the door opening. If inside mounted, minimum of 3.75" clearance for "Wall" dimension is required. (Figure 3) Wall 2.5" 11" Wall Figure 3 - Live Shaft Clearances Minimum Shaft Length Past Door Bracket A minimum of 1.5" of shaft is required (2.5" recommended) for mounting the door sprocket to the Live Door Shaft. (Figure 3) 2