# Motor Selection Guide ### The Concept Of Torque

Whatever the application, be it a motorized blind, shade, drapery or awning, a specific torque (lifting capacity) will be required to motorize the operation. The speed at which the application will then operate depends on the designated speed (RPM) of the motor.

Therefore, the main criteria for motor selection is torque. The following selector charts are based on the torques each of the motors will produce for various applications under different parameters.

Torque is literally described as the "rotary force within a mechanism". More technically: the product of a force and its perpendicular distance from a point about which it causes rotation or torsion. Torque = Load x Radius

Example: A 1 pound weight hanging from a rope turning around a 1 inch radius roller tube tends to rotate the tube as indicated by the arrow. (see figure 1). This weight generates a torque equal to 1in. lb. By definition: if the same weight is hanging on a 2 inch radius, the torque applied to the tube is equivalent to 2 in. lbs. (see figure 2). Therefore, the torque generated by the same weight doubles when the tube radius doubles. There is a direct relation between torque and roller tube radius as shown in figures 1 & 2. ### Theoretical Lifting Capacity

The theoretical lifting capacity is an indicator of the torque capability of the motor. However, the actual load values will differ depending on many factors including tube diameter, tube length, material, friction and type of accessories used. Under no circumstances shall the maximum load including all accessories (including the tube) in the system (between the 2 motor brackets) exceed the maximum load rating of system's individual components.

For all LS40 motors the theoretical lifting capacity is given on a 40 mm (1.57") tube. Length and tube deflection will determine its load capacity.

For all LT50 motors theoretical lifting capacity is given on a 2" tube. Length and tube's deflection will determine its load capacity.

For all LT60 motors theoretical lifting capacity is given on a 2.5" tube. Length and tube's deflection will determine its load capacity.