© Siemens AG 2015 FLENDER Standard Couplings Coupling Preselection and Options Selection of the coupling size Coupling load under maximum and overload conditions The maximum torque is the highest load acting on the coupling in normal operation. Maximum torques at a frequency of up to 25 times an hour are permitted and must be lower than the maximum coupling torque. Examples of maximum torque conditions are: Starting opera- tions, stopping operations or usual operating conditions with maximum load. Coupling behavior under overload conditions The ZAPEX, ARPEX, N-EUPEX, RUPEX and N-BIPEX coupling series can withstand overloads until the breakage of metal parts.
These coupling series are designated as fail-safe. The N-EUPEX DS, ELPEX-B, ELPEX-S and ELPEX coupling se- ries throw overload. The elastomer element of these couplings is irreparably damaged without damage to metal parts when sub- jected to excessive overload. These coupling series are desig- nated as non-fail-safe. These types that fail can be fitted with a so-called fail-safe device. This additional component enables emergency operation, even after the rubber element of the cou- pling has been irreparably damaged. T Kmax ≥ T max ⋅ FT 3 Overload torques are maximum loads which occur only in com- bination with special, infrequent operating conditions.
Examples of overload torque conditions are: Motor short circuit, emergency stop or blocking because of component breakage. Overload torques at a frequency of once a month are permitted and must be lower than the overload torque of the coupling. The overload condition may last only a short while, i.e. fractions of a second. Checking shaft-hub connection The torques specified in the tables of power ratings data of the coupling series do not necessarily apply to the shaft-hub con- nection. Depending on the shaft-hub connection, proof of form stability is required. Siemens recommends obtaining proof of form strength by using calculation methods in accordance with the current state of the art.
T KOL ≥ T OL ⋅ FT Coupling load due to dynamic torque load Applying the frequency factor, the dynamic torque load must be lower than the coupling fatigue torque. Dynamic torque load T KW ≥ T W ⋅ FF ⋅ FB – 1.0 1.5 Frequency of the dynamic torque load f err ≤ 10 Hz frequency factor FF = 1.0 Fitting recommendations for the shaft-hub connection are given in catalog section 15. Frequency of the dynamic torque load f err > 10 Hz frequency factor FF = √ ( f err /10 Hz) The coupling hub is frequently fitted flush with the shaft end face. If the shaft projects, the risk of collision with other coupling parts must be checked.
If the shaft is set back, in addition to the load- bearing capacity of the shaft-hub connection, the correct posi- tioning of the hub must be ensured as well. If the bearing hub length is insufficient, restorative forces may cause tilting move- ments and so wear to and impairment of the axial retention. Also, the position of the set screw to be positioned on sufficient shaft or parallel key material must be noted. For the ZAPEX and ARPEX series, the frequency factor is always FF = 1.0.
Checking the maximum speed For all load situations n Kmax ≥ n max Checking permitted shaft misalignment For all load situations, the actual shaft misalignment must be less than the permitted shaft misalignment. Checking low temperature and chemically aggressive environment Checking bore diameter, mounting geometry and coupling design The minimum permitted coupling temperature is specified in the Temperature factor FT table. In the case of chemically aggres- sive environments, please consult the manufacturer. The check must be made on the basis of the dimension tables. The maximum bore diameter applies to parallel keyways to DIN 6885.
For other keyway geometries, the maximum bore diameter can be reduced. On request, couplings with adapted geometry can be provided. 3/7 Siemens MD 10.1 · 2015 Shaft-hub connection Suggestion for calculation method Keyway connection to DIN 6885-1 DIN 6892 Shrink fit DIN 7190 Spline to DIN 5480 Bolted flange connection VDI 2230 Flange connection with close-fitting bolts