Advantages compared to conventional systems ® SIT-LOCK Keyless Locking Elements 3 www.jbj.co.uk/couplings.html #DriveLineHarmony Interference Fit Interference fit shaft-hub connections can be achieved by cooling the shaft or heating the hub. This type of connection is not widely used for the following reasons: » Requires tight tolerances. » Difficult to remove. » Locking area temperature changes. » The effect of the centrifugal force created by the hub can decrease transmissible torque. » Increased stress concentrated on the edges. Shaft strength depends on the type of coupling used As an example, we look at the following data. For a shaft with a diameter d equal to 50 mm, its shaft strength would match the diameter of: » 39 mm feather key coupling. » 35 mm splined shaft coupling. » 46 mm interference fit. » ® 49 mm SIT-LOCK coupling. Note Incorrect calculations that do not account for all the stresses in a shaft-hub coupling can cause irreparable shaft breakage. Below is an example of fatigue failure caused by shaft-hub locking using a feather key. SIT-LOCK® locking device coupling Simply by tightening the screws, SIT-LOCK® keyless locking devices create an axial force on the shaft and the hub that is spread over the entire contact surface. Unlike traditional systems, they offer numerous advantages. The main ones are listed below. Calculation ease All the information, transmissible torque, axial force limits, etc., can be found in the catalogue. No additional calculations are required. Installation and removal Quick and easy. When installing, the screws simply need to be tightened to the Ms value indicated in the table. For removal, however, the screws need to be loosened evenly. In addition, there are assembly threads that allow the coupled parts to unlock even under extreme conditions. Shaft and hub tolerances and surface finish Tight tolerances are not necessary. h8/H8 tolerances are typically used. Some products may allow for h11/H11 tolerances. All the information is available in the catalogue. Operating temperatures The values shown in the tables are valid for temperatures from -20 °C to +200 °C. For uses lower or higher than these values, please contact the jbj Techniques Limited technical office, telephone: +44 (0)1737 767493 or email: info@jbj.co.uk Simultaneous loads possible Using SIT-LOCK® locking devices allows simultaneous torque, axial force, bending moment and radial force. For further information or calculations, please contact the jbj Techniques Limited technical office, telephone: +44 (0)1737 767493 or email: info@jbj.co.uk Increased shaft strength The shaft has no slots and the pressure generated by tightening the screws does not cause any reduction of the shaft’s strength. This enables the diameter of the shaft to be reduced with the same stresses applied, leading to considerable savings on costs. Easy axial and angular adjustment ® Unlike conventional couplings, SIT-LOCK locking devices simply require placing the hub in the desired position relative to the shaft and tightening the screws. DMi DAe DMe DF
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