www.jbj.co.uk/couplings.html #DriveLineHarmony Applications with simultaneous torque and axial force SIT-LOCK® locking devices can simultaneously transmit torque Mt and tolerate an axial force F . The table shows the maximum permissible values. Where ax both values are present simultaneously, the transmissible torque M value decreases. t Below is the formula for calculating transmissible torque: 2 2 M = M+(F •d) tam t AXR 2000 M = permissible torque (Nm) tam M = torque stated in table (Nm) t F = required axial force (N) AXR d = shaft diameter (mm) Radial force influence The radial force F affects the contact pressure on the shaft and hub generated by the locking device. Radial force generates an increase in pressure P R n generated on the hub. It is highly important to calculate this value as it must be used to verify the minimum hub diameter D . min Δ = F Pn R D • H Δ = additional pressure on hub (N/mm²) Pn F = radial force applied (N) R D = external diameter of the locking device (mm) H = locking device outer ring width (mm) Safety factors The transmissible torque Mt and tolerable axial force F values stated in the catalogue must not be exceeded. The design phase should take any service ax factors into account. Applications on shafts with bores For use on a shaft with a bore corresponding to the pressure P , the maximum bore diameter d should be: w B d ≤ s • P • d B 0.2 - 1.6 w s0.2 The maximum bore dB will depend on the elastic load σ of the shaft material and the surface pressure P generated by the locking device (see table 0,2 w values). For hollow shaft applications, locking devices that generate low pressure are recommended. Calculating the minimum hub diameter Dmin ® To guarantee the torque transmission Mt indicated in the table when using a SIT-LOCK internal locking device, the screws must be tightened to a specific torque Ms. Tightening the screws creates a pressure on the shaft Pw and on the hub Pn. To calculate the minimum hub diameter D , the min formula generally used for measuring the thickness of thick-walled cylinders subject to high internal pressure is used. The formula for calculating D is: min D ≥ D • K min D = outer diameter of the locking device in mm K = application coefficient See table below. The coefficient K is given by the following formula: K = s +(X•P ) 0.2 n s -(X•P ) 0.2 n Where: σ = hub material elastic limit in N/mm² 0,2 X = factor depending on hub shape and width P = surface pressure on the hub n Formulas for Correct Use ® SIT-LOCK Keyless Locking Elements 5 ( (
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