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R+W Series EK - Selection Service Factors
The behavior of elastomer couplings are dependent on operational parameters, such as amplitude, frequency, and temperature. These properties are approximated by the use of operational factors. The factors to be considered when sizing elastomer couplings are:
- Temperature Factor
- Start Factor
- Impact Factor
The temperature factor accounts for the behavior of the elastomer insert at various temperatures. High and low temperatures will negatively affect the torque capacity of the elastomer insert. Therefore, larger couplings may be required in extreme temperature situations.
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Temperature Factors
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Temperature
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Type A
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Type B
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Type C
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-30° C
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1.5
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1.7
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1.4
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+20° C
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1.0
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1.0
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1.0
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+40° C
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1.2
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1.1
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1.3
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+60° C
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1.4
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1.3
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1.5
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+80° C
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1.7
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1.5
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1.8
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+100° C
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2.0
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1.8
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2.1
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The start factor relates to the number of machine starts per hour. Since the moment of inertia of the driven end exerts additional load on the coupling during start up, the coupling has to be designed for a higher torque to avoid degradation of the service life.
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Start Factors
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Starts/Hour
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Up to 120
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120 - 240
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240+
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Factor
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1.0
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1.3
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Upon Request
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The impact factor relates to operational impacts, intermittent loads, shocks, or changes in direction. This is similar to the service factor common in gearbox selection. These types of influences can significantly affect the service life of the coupling.
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Impact Factors
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Load
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Factor
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Uniform, Light Duty, Continuous
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1.0
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Non-Uniform, Periodic Load Changes,
Rare Direction Changes
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1.8
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High Dynamics, Frequent Direction Changes
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2.5
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Taking into account the operational conditions and characteristics of the application, through the use of the appropriate factors, will assure the proper selection and service life of an elastomer insert jaw coupling.
Adjusted Torque = Calculated Torque x Temperature Factor x Start Factor x Impact Factor
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