7 1 Power Requirements (Speed / Torque / Duty Cycle) • Most servo applications include speed and torque profiles that vary with time • Gearing technologies have speed and torque ratings that account for these cyclic type applications • Calculations for average toque and speed are derived from life limiting gear train elements • Speed and torque calculations are generally tied to a service life, and will often, but not always, dictate frame size selection • Methodology for calculating average torques and speeds & ultimately service life, varies from technology to technology 2 Output Bearing Requirements (Load Support / Accuracy) • Servo gear reduction technologies often include a bearing system supporting the rotating output (shaft or flange) • Many applications require a specific level of tilting moment capacity and / or tilting stiffness during operation • Output bearing service life calculations need to be performed when the output element is subjected to significant radial or axial forces • Gearhead size selection is often based on output bearing load capacity or true running accuracy 3 Accuracy / Repeatability Requirements • Determined by torsional backlash, torsional stiffness, and gearing transmission accuracy • Influenced by tilting moment stiffness and output bearing accuracy (concentricity, runout, & parallelism) 4 Inertial Match / Ratio Requirement • Most servo gearhead selections are focused on inertia matching • Other gearhead design selection criteria include torque amplification, motor speed optimization, and output bearing capacity / rigidity 5 Motor Mounting Requirements • Ease of motor assembly • Reliability and accuracy of motor shaft connection • Range of motor face / shaft sizes which can be accommodated 6 Backlash Requirements • High performance: 1 arc minute maximum • Servo grade: 3 arc minutes maximum • Medium performance: 10 arc minutes maximum • Stepper grade: 20 arc minutes maximum 7 Form Factor / Size / Weight/Envelope • Weight vs. Power density considerations • Thermal considerations (material selection / heat dissipation) • Space & sizing requirements FACTORS TO CONSIDER WHEN CHOOSING THE RIGHT GEAR TECHNOLOGY Call to learn more 800.921.3332 Visit our website at www.HarmonicDrive.net Click to watch our videos Choosing a drive involves several design factors that depend greatly on the task at hand. For more precise and exact movements, drives that have a high accuracy and repeatability are required. If a task requires a high torque output or speed, a larger drive or one with specific gear ratios will be necessary. The following is a list of the Top 7 design aspects you need to know that include sizing, mounting, speed, torque, accuracy, and repeatability.