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Power transmission capacity

Torque transmitted by the OKC coupling is directly proportional to the surface pressure between the inner sleeve of the coupling and the shaft after the outer sleeve has been driven up axially. The necessary drive-up, which is reached when the diameter of the outer sleeve has increased by dimension ΔD for OKC, OKCS and OKCX couplings, and the stated drive-up length for OKF couplings given in the tables, will ensure a pressure of 120 N/mm2 for OKC and OKCS couplings, 70 N/mm2 for OKCX couplings and 100 N/mm2 for OKF couplings.
The table lists the maximum torque which can be transmitted calculated using the equation:
Mtmax = π da2 B p μ / 2000

Mtmax=maximum transmissible torque [Nm]
da=shaft diameter [mm]
B=effective pressure length (equal to da) [mm]
p=minimum surface pressure between shaft and inner sleeve [N/mm2]
  • 120 N/mm2 for OKC and OKCS
  • 70 N/mm2 for OKCX
  • 100 N/mm2 for OKF
coefficient of friction (0,14, for OKCX 0,3)
If the coupling is subjected to axial forces, their effect on the power transmission capacity is generally insignificant. The transmissible torque is obtained from the equation

Mt = √(Mtmax2 - ( Fa da / 2000)2)

Mtmax=maximum transmissible torque [Nm]
Fa=axial force [N]
da=shaft diameter [mm]
The permissible torque is obtained from:

M = Mtmax or Mt / f

M=permissible torque [Nm]
Mtmax=maximum transmissible torque [Nm]
f=safety factor, which can be selected from the table
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