One of the upsides to locking assemblies—especially compared to traditional keyways—is their ability to safely transmit combined loads in heavy equipment. This feature recently came in handy for an impact crusher—a machine that uses striking instead of pressure to reduce the size of rocks and other hard materials.

Here’s how we modified one of our standard locking assemblies to tolerate the bending moments and radial loads in an impact crusher.

How Impact Crushers Operate

First, a spinning rotor equipped with blow bars catches the material. Next, the machine accelerates and hurls the material against the breaker plates, which serve as the stationary impact wall. The machine then feeds the material back to the rotor.

Material fragmentation continues in this way until the material is small enough to pass through the gap between the rotor and breaker plates.

Application Requirements

A German-based construction company consulted us for locking assemblies that could reliably absorb its impact crusher’s combined loads—including bending moments and radial impact forces.

To meet these requirements, we paid special attention to the yield point of our locking assemblies’ individual rings. Our goal was to avoid plastic deformation in the locking assembly. Doing so would prevent the impact crusher from incurring damage—even under extreme circumstances, such as overloading.

At the same time, we had to avoid reducing the minimum pressure, which could cause axial rotor wandering—or shaft breakage—due to fretting corrosion.

Building On Our Standard Locking Assemblies

At Ringfeder, if one of our standard components can’t fulfill a customer’s requirements, we develop a custom solution that will. In this case, we adapted our RfN 7012 Locking Assembly to have a higher yield strength, narrower taper angle and wider thrust rings. Thanks to these modifications, our locking assemblies were a success in the impact crusher.

Designed to Tolerate Bending Moments

We design our locking devices to tolerate bending moments by using materials with a 40-percent higher yield strength than standard locking assemblies. Our wider designs also have a higher resistance to moment forces. And finally, we optimize the number and location of bolt holes in the assembly’s pressure ring—reducing the working stresses the assembly can tolerate.

Thanks to these design features, our locking assemblies are a perfect fit for demanding applications like impact crushers. In addition to securing the rotor, you can use them to secure the belt pulleys. These pulleys must be fastened onto the crusher shaft in such a way that torque is safely transmitted until the pulley slips or the shear pin breaks.

To learn more about our locking assemblies, visit our product page.

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