Harmonic Drive CSD-2A Component Sets Engineering Data page 34

Bearing Support for Input and Output Shafts
For component sets, both input and output shafts must be supported by two adequately spaced bearings in order to
withstand external radial and axial forces without excessive deflection. Even when only limited external loads are anticipated
both input and output shafts must be fixed axially in order to avoid damage to the component set. Bearings must be
selec-ted whose radial play does not exceed ISO-standard C2 class or "normal" class. To fully exploit the accuracy of the
gear we recommend a stiff output bearing design. The bearing should be axially and radially preloaded to eliminate backlash.
Examples of correct bearing arrangements are shown on the left.
Illustration 34.1
Screw connections
The high torque capacity combined with the compact design of the Harmonic Drive® Gear demands a secure connection of
both Flexspline and Circular Spline. To ensure that the screw connection is adequate please observe the following general
guidelines:
• Base the calculation of torque transmitting capability on the VDI 2230 guideline.
• Use 12.9 quality screws.
• Do not use unsuitable locking devices such as spring washers or toothed discs.
• Ensure that the strength of the output shaft material is adequate.
• Ensure that the flange material is suitable for the pressure beneath the screw heads.
• Steel or cast iron is the preferred material for the female thread.
• Reduce the roughness of the mating surface to reduce the loss of preload by embedding.
• Ensure largest possible clamping length ratio (thickness of the clamped flanges versus diameter of the bolts).
• Clean, degrease and dry all mating surfaces to ensure adequate coefficient of friction. Loctite 574 can be
applied to increase friction.
• Use approved screw tightening devices (torque wrench, torsional angle or yield controlled torque wrench if possible).
• Apply Loctite No. 243 to the threads of bolts.
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1019659 11/2014