Standard_Parts_Catalogue

Page 1696 | 3.6 Moving, Transferring, Connecting with Shafts and Joints Couplings Technical Information / Definition of Terms Rated torque The torque that the coupling can transmit continuously. This value allows for load fluctuations during operation so that rated torque compensation is not required when selecting the couplings (excluding Oldham types). Select a coupling such that the load torque generated during continuous operation does not exceed the rated torque. Maximum torque The torque that the coupling can transmit momentarily. Rotational speed The maximum rotational speed of the coupling was calculated based on a peripheral speed of 33 m/s. Tests have confir- med that the coupling will not sustain damage at this speed. Moment of inertia (rotating mass) This indicates the coupling’s resistance to rotation around its own axis. The lower the moment of inertia, the less load torque is required for starting and stopping the motor. Slip torque Slip torque refers to the torque at which the shaft begins to slip out of the clamping hub. This presumes that the clamping hub was installed at the specified screw tightening torque. The slip torque values given in the table were derived from experimental testing. They are based on a shaft tolerance of h7, a shaft hardness of 34 to 40 HRC and the screw tightening torque for the clamping hub given in the table. The load torque must be less than the slip torque for which the coupling is designed. It is also necessary to take into account that the slip torques given in the table are lower than the indicated maximum torque values. If no slip torque is specified, then the maximum torque can be achieved. Because the slip torque changes due to operating conditions, the suitability of the selected coupling should be tested under real conditions. GN 2240 d 1 d 2 / d 3 Slip torque in Nm ≈ Tightening torque of the screw in Nm ≈ 14  3 0,8 0,5 14  4 1,4 0,5 14  5 2,1 0,5 14  6 1,3 0,25 20  5 4,9 1 20  6 6,4 1 20  8 9,4 1 30  8 9,3 3,5 30 10 14,6 3,5 Static torsional stiffness The static torsional stiffness indicates the number of degrees by which a coupling twists depending on the introduced torque. Torsional stiffness is generally indicated as torque per unit of arc (Nm/rad). To simplify the design process, the torsional stiffness can also be converted to degrees per Nm. Where: 2π rad = 360° → Example: Coupling with a torsional stiffness of 500 Nm/rad = 1 rad = 360° = 180° ≈ 57,3° 2π π 500 Nm → Reciprocal 57,3° ≈ 0,1146° 57,3° 500 Nm 1 Nm