Lenze DSD - Manual (Page 332)

11 Drive Dimensioning
11.4 Lenze gearbox selection
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Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
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11.4 Lenze gearbox selection
11.4.1 Check of the torque load
The torque load considerably influences the service life of the gearbox. The load is considered in the
dimensioning phase.
• DSD calculates the fatique strength according to the Wöhler curve.
Load test according to the Wöhler curve ( 332)
• DSD calculates alternating loads which occur at torque reversals.
Alternating load and repeated load cycle with regard to toothed gearboxes ( 334)
11.4.1.1 Load test according to the Wöhler curve
The Wöhler characteristic describes the "static strength", the "fatique strength", and the "endurance
strength" of toothed gearboxes.
Static strength
• If the number of duty cycles is below 1000, the torque of the static strength can be utilised.
• The double rated torque M
per,out
is defined as the limit of the static strength in the DSD.
Endurance strength
• The torque does not exceed M
per,out
.
• The service life is not limited by the number of duty cycles.
Fatique strength
• The torque may be > M
per,out
, however it must not occur too frequently.
• According to the load, the service is between 10 3 and 3 × 10 6 load cycles.
• Every operation in the range of static strength and fatique strength affects the gearbox. If an
accordingly great number of load cycles is reached, massive damage (e. g. fractures of the teeth
or shaft) can occur.
• DSD carries out a fatigue strength calculation based on the Wöhler curve.
• The approached points of the motion profile serve to calculate a theoretical damage of the
gear toothing. Then, the theoretical damage after five years is determined, considering a dai-
ly operating time.
• This test is simplified but safe.

Note!
Contact your Lenze sales partner if the result of the fatigue strength calculation is too
negative. Based on the DSD project, the Lenze experts can carry out a detailed test.