Correct coupling selection guide 8 #DriveLineHarmony Formula Symbols Mechanical Power Transmission Couplings Name Symbols Unit Explanation Torsional stiffness, dynamic CT Nm/rad For calculating torsional vibration. dyn Excitation frequency f Hz Excitation frequency of motor or driven machine. err 2 Moment of inertia J kgm Moment of inertia of coupling sides 1 and 2. Axial misalignment ΔK mm Axial misalignment of the coupling halves. a Radial misalignment ΔK mm Radial misalignment of the coupling halves. r Angular misalignment ΔK ° Angular misalignment of the coupling halves. w Factor expressing the real coupling load as a ratio of the Service factor FB nominal coupling load. Factor expressing the frequency dependence of the fatigue Frequency factor FF torque load. Factor taking into account the reduction in strength of flexible Temperature factor FT rubber materials at a higher temperature. Weight m kg Weight of the coupling. Rated speed n rpm Coupling speed. N Maximum coupling speed n rpm Maximum permissible coupling speed. Kmax Rated output on the coupling, usually the output of the driven Rated power P kW N machine. Rated torque T Nm Rated torque as nominal load on the coupling. N Fatigue torque T Nm Amplitude of the dynamic coupling load. W Maximum torque T Nm More frequently occurring maximum load, e.g. during starting. max Very infrequently occurring maximum load, e.g. during short Overload torque T Nm OL circuit or blocking conditions. Torque which can be transmitted as static torque by the Rated coupling torque T Nm KN coupling over the period of use. Torque which can be frequently transmitted (up to 25 times an Maximum coupling torque T Nm Kmax hour) as maximum torque by the coupling. Torque which can very infrequently be transmitted as maximum Coupling overload torque T Nm KOL torque by the coupling. Torque amplitude which can be transmitted by the coupling as Fatigue coupling torque T Nm KW dynamic torque at a frequency of 10 Hz over the period of use. Resonance factor V Factor specifying the torque increase at resonance. R Temperature T °C Ambient temperature of the coupling in operation a Damping coefficient Ψ psi Damping parameter