3
Motor Selection
When choosing the correct Central Motor it is important to understand the application, as well as the size, weight and condition of the door. First, identify
the type of rolling door you will be working with. For example is it a Slat Door, Grid Door, Glass Door, Wood door, etc. Common applications for these doors
include small store fronts, garage doors, mall store fronts, hotels/motels, etc. Each door type has specific requirements.
Regardless of the motor being specified, you MUST know the diameter of the motor crown, weight of the door, and the overall height and width of the door.
Use the following chart to select the appropriate motor for your application.
Application
Central Motors are electric motors used with rolling type doors (Slat, Grill,
etc...) that roll-up around the shaft on the crown of the motor. The Central
Motor is to be used only with a balanced door. The motor housing is
mounted around the dead shaft and its internal electric motor rotates a gear-
driven crown attached/bolted to the rolling door. The door rolls around the
crown when opening the door and unrolls when the door is closing. This type
of motor is frequently used when there is not enough space on the sides of
the door for a chain or gear-driven motor. Rolling doors used with Central
Motors should not be confused with side-driven motors used on rolling sheet
steel doors.
Central Motors are for use on dead shafts ONLY ranging from 1.65" (42 mm)
to 2.99" (76 mm), with 2.36" (60 mm) being the most common size.
• If the dead shaft is 1.89" (48 mm) in diameter and the inside motor diameter
is 2.36" (60 mm), reduction spacers part number CM-48SA (provided) are
required.
• If the dead shaft is 2.36" (60 mm) in diameter and the inside motor diameter
is 2.99" (76 mm), reduction spacers part number CM-60SA (provided) are
required.
Terms you should be familiar with:
• Dead shaft: A dead shaft is a door shaft firmly mounted to the header wall
and does not rotate.
• Balancing mechanism: A door with a balancing mechanism such as a coil
spring or band spring for counter balancing the weight of the door. The
illustration shows a central motor mounted to a dead shaft with banded
springs installed. Coil springs are also frequently used with a dead shaft
and provide the same function of reducing the force required to lift the
door.
Consult the door manufacturer or professional installer if you are not sure
what type of door and springs you are working with.
Central Motor
Dead Shaft Band Spring
Door
Determining the Right Size Motor Example (Standard) Example (Metric)
Identify Type of Rolling Door Slat
Slat, Grid, Other Grid
Other
Size of Door
Width 10' 3.04m
Height 9' 2.74m
Calculate Square Feet (width x height) 90' 27.43m
Door Material Steel
Aluminum
Other
Door Gauge Material 21
Weight per Square Foot 3 lbs. 1.4 kg
Total Door Weight (Sq. ft. x lbs. per sq. ft.) 270 lbs. 122 kg
Motor should be rated for 120% of door weight 324 lbs. 147 kg
Choose Next Largest Capacity Motor All Lift Capacities are at the Rated Load
LM-1600 330 lbs. 150 kg
LM-1600HV 330 lbs. 150 kg
LM-2000 396 lbs. 180 kg
LM-2000HV 396 lbs. 180 kg
LM-2800/LM-2800HV 616 lbs. 280 kg
LM-3600/LM-3600HV 792 lbs. 360 kg
