An Explanation of Servo-Reducers

Servo applications are typically very demanding applications which require high-quality and precision drive components, such as servo reducers, to reach the desired level of performance.  Andantex USA offers several different types of servo-reducers, including cycloidal and servo-worm.  The following information explains the different types, characteristics, and the applications in which they are used:

Important Servo-Reducer Attributes:

• Low Backlash:  Backlash in a servo reducer reduces the level of performance of the system, causing it to "hunt" for position.  Duty cycles that have a high number of torque and direction reversals require low backlash to minimize the effects of the reversals (shock loading, fretting, etc.)
  
  
• High Torsional Rigidity, aka Stiffness:  High stiffness is necessary to reduce the amount of  torsional deflection, or windup, in a servo-system.   This windup can cause a system to "hunt" for position and excite vibrations.
  
  
• High Input Speed Capacity:  This is necessary to handle high reduction ratios and to reduce the reflected load inertia at the servo-motor.  The reflected load inertia at the servo-motor is divided by the square of the reduction ratio.
  
  
• Backdrivability, aka Reversibility:  This is the ability of the reducer to drive the input shaft from the output shaft.  When driving large inertias, the inertia can begin to drive the reducer from the output when decelerating.  This typically depends on the ratio and efficiency of the reducer.
  
  
• Wide Reduction Ratio Range:  A wide range of reduction ratios helps to match the motor parameters (speed, inertia, torque) to the load parameters (speed, inertia, torque).
  
  
• Low Input Inertia:  This should be minimized since the servo-motor is accelerating and decelerating this inertia in addition to the load inertia of the system, thereby reducing the efficiency of the system.  Furthermore, this increases the total inertia of the system and can affect the inertia mismatch between the system inertia and the motor inertia.
  
  
• Low Transmission Error:  Transmission error is the deviation of the angular position of the output shaft of a reducer, compared to the theoretical angular position of the shaft as driven by the input shaft through the reduction ratio.  This deviation can cause a jump in angular velocity and vibrations, and effect the smoothness of the system.
  
  
• Compact:  Servo-reducers are often used on axis which are moving.   Therefore, it is essential that they provide high torque to volume and weight ratios to minimize the system drive power requirements.

Servo-Reducer Comparison:

To insure proper selection, please consult the factory.  If you have any questions regarding the information provided here or require more information, please call us at (800) 713-6170 or e-mail us. Our Sales and Engineering departments are ready to help you with your specific power transmission needs.