www.jbj.co.uk/couplings.html #DriveLineHarmony Oxidation protection Even in damp environments, the pressures created along the contact surfaces do not allow for oxidation, ensuring easy removal of the locked parts. No backlash ® Connection in transmissions using SIT-LOCK locking devices are perfectly rigid and there is no backlash that could impair motion transmission or machine precision over time. Recommended for applications subject to continuous alternating loads ® By using SIT-LOCK locking devices, the stresses generated by alternating or sudden loads are distributed over the entire surface of the shaft and not over a reduced section as occurs with traditional systems. Formulas for proper SIT-LOCK® locking device use By tightening the screws to the torque M indicated in the table, an axial force P occurs which generates a radial force N on the shaft and hub contact surfaces. s v The pressure generated on the shaft and hub determines the transmissible torque M indicated in the table. t Therefore: M = N • μ • d t 2 The coefficient of friction μ used to calculate the locking device transmissible torque M is: t 0.12 (oiled surfaces) for internal locking devices. 0.15 (dry surfaces) for external locking devices. This means that for the locking devices with calculated values, with a coefficient of friction μ 0.12, a higher torque can be transmitted without further increasing the screw tightening torque M. Contact jbj Techniques Limited technical office, telephone: +44 (0)1737 767493 or email: info@jbj.co.uk for further s clarifications and calculations. Avoid using molybdenum disulphide based lubricants or greases on the shaft and hub contact surfaces as this would considerably decrease the friction coefficient μ. Calculating the minimum hub diameter Dmin See the following pages. Screw tightening torque Ms Where necessary, the screw tightening torque Ms can be reduced. As a result, the transmissible torque M indicated in the tables decreases proportionally. t The same applies to the axial force limits F and the pressure generated on the shaft P and hub P . ax w n The tightening torque M can be decreased by 30% or 40% of the value indicated in the tables. s Temperature influence The values in the table are typically valid for applications from -20°C to +200°C. In extreme cases, it is possible to use them from -40°C to +300°C. For applications subject to high temperatures, we recommend using shafts and hubs with the same coefficient of thermal expansion. For more details, please contact jbj Techniques Limited technical office, telephone: +44 (0)1737 767493 or email: info@jbj.co.uk Formulas for Correct Use ® SIT-LOCK Keyless Locking Elements 4 Dmin
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