Safety couplings are always used where moving masses can cause considerable damage in the event of sudden breakdowns. These are, for example, the electric motors, which can completely destroy an extruder gear with the inertia of a twin-screw extruder in the event of a sudden blockage of the extruder screws.
Safety couplings are also called torque limiters, as they reliably protect inadmissible torque overshoots.
In addition to slipping clutches, load-releasing disconnect couplings have proved their worth.
The product range of the safety couplings is divided into compact couplings series 400 and series XG as well as in module couplings series 820.
The AUTOGARD company is one of the market leaders here and has created a reliable coupling system with the 400 series. This coupling is very compact and is available in different versions for a torque up to 24860 Nm.
The operating principle is simple: with spring loaded several balls transfer the torque from the drive to the output. In the event of an overload, the balls are pushed out of their seats and the clutch is released. The spring force is linear to the transmittable torque and very accurately adjustable.
The couplings of the 400 series is re-engaged by reversing the driving direction, this can be done manually or controlled by the drive motor.
Compact couplings are the 400 series described above and the new XG series optimized for extruder applications.
Typical applications include, in addition to extrusion plant for example rotary valves, tunnel boring machines or screw presses.
For the highest torques and a wide variety of applications, Autogard has developed the 800 series.
Here, the torque is transmitted by modules. These modules are calibrated to a specific torque and then lock in case of overload. The clutch is in the freewheel.
This module coupling is engaged manually by aligning the coupling flanges and generating a pulse on the module with a rubber hammer.
Modular couplings are used, for example, on scissors drives and can be combined with toothed couplings, cardan shafts but also with all elastic and torsionally rigid couplings.
Torques up to 1 million Nm are possible.