| Model Number | IN-U21 | IN-U22 | IN-U23 | 
  
    | Drawing Number | list | list | list | 
  
    | Environment | IN | IN | IN | 
  
    | Motor | U21 | U22 | U23 | 
  
    | Pricing | IN-U21 | IN-U22 | IN-U23 | 
 
  
    | NEMA Frame Size | 23 | 23 | 23 | 
  
    | Number of Magnetic Stacks | 1 | 2 | 3 | 
  
    | Step Angle | 1.8 | 1.8 | 1.8 | 
  
    | Accuracy Grade (%) | 3 | 3 | 3 | 
  
    | Detent Torque (oz-in) | 6 | 15 | 21 | 
  
    | Static Torque At Thermal Current
      {unipolar} (oz-in) | 45 | 80 | 120 | 
  
    | Static Torque At Thermal Current
      {parallel} (oz-in) | 50 | 85 | 110 | 
  
    | Static Torque At Thermal Current
      {series} (oz-in) | 60 | 110 | 130 | 
  
    | Thermal Current {unipolar} (A) | 1.4 | 1.6 | 2.0 | 
  
    | Thermal Current {parallel} (A) | 1.6 | 1.8 | 2.3 | 
  
    | Thermal Current {series} (A) | 1.0 | 1.4 | 1.8 | 
  
    | Single Coil Inductance (mH) | 4.2 | 4.15 | 4 | 
  
    | Single Coil Resistance (ohm) | 3.6 | 2.9 | 2.6 | 
  
    | Series Inductance (mH) | 16.8 | 16.6 | 16 | 
  
    | Series Resistance (ohm) | 7.2 | 5.8 | 5.2 | 
  
    | Bearing Type | C/F | C/F | C/F | 
  
    | Bearing Thrust Load (lbs) | 25 | 25 | 25 | 
  
    | Bearing Radial Load (lbs) | 50 | 50 | 50 | 
  
    | Bearing End Play (10-3 in) | C/F | C/F | C/F | 
  
    | Bearing Radial Play (10-3 in) | 8 | 8 | 8 | 
  
    | Rotor Inertia (oz-in2) | 0.48 | 1.28 | 1.75 | 
  
    | Body Diameter (in) | 2.3 | 2.3 | 2.3 | 
  
    | Body Length (in) | 2 | 3.1 | 4 | 
  
    | Weight (lbs) | 1.6 | 2.4 | 3.2 |