How Torque Limiters Protect Equipment from Mechanical Overloads and Excessive Torque

How torque limiters protect equipment from mechanical overloads


The cement and mining industries rely on powerful equipment to grind down rocks and earthen material. These machines use a lot of power to generate the torque necessary to get the job done. However, too much power in the form of an uneven torque load can damage equipment and lead to downtime. The best way to protect equipment is by using a torque limiter.

A Crushing Job: Two Types of Mills 

Two of the most common methods of breaking down rocks and other materials are ball mills and semi-autogenous grinding (SAG) mills. Ball mills crush material by using balls in a long-angled rotating cylinder. SAG mills are similar, but with the addition of relying on the material itself to help grind the aggregate into a smaller size.  

Ball and SAG mills work with material of different sizes and densities, and both take a lot of power to do their jobs. The power required for the work leads to the possibility of uneven torque loads on the system. Uneven torque loads lead to mechanical overloads, and mechanical overloads cause unplanned downtime and damaged equipment

Mechanical Overloads: Too Much Torque 

When the rotating components of a mill experience torque beyond what the system is designed to handle, you’ll get a mechanical overload. Excess force from a mechanical overload can cause: 
  • Damage to couplings, drive or motor shafts; 
  • Gearing damage;  
  • Ring gear jamming; and 
  • Broken drive trains and enclosed gear drives.

A single overload could cause a fracture or complete failure of critical drive components. Damaged equipment means less uptime, lower productivity, and increased maintenance costs.

Torque Limiters: Protecting the System  

Torque limiters are the best way to protect high-powered equipment from excess torque and the resulting mechanical overloads. Torque limiting couplings are typically added to high-speed shafts.  

When a torque overload happens on a system with a properly installed torque limiter, the limiter will slip and stop the system. The torque limiter disconnects the drive shaft from the components it powers. The torque limiter acts like a circuit breaker, allowing the energy to dissipate without causing excess damage. When in place, a torque limiter reduces the likelihood of gear drive damage.  

After an overload, the torque limiter can be reset and normal operations can resume immediately. Torque limiters are essential for reliable power transmission in heavy duty environments.

Autogard: 80 Years of Overload Protection 

Rexnord Autogard 820 Torque Limiter

Torque limiters provide the protection heavy industry applications need. With more than 80 years’ experience in providing overload protection, Regal Rexnord's Autogard Torque Limiter is the optimal solution for heavy duty high-shock loading applications. Autogard attaches to a high-speed drive shaft and guards equipment by providing disengagement protection. With a wide range of mounting configurations, Autogard makes it easy to fit a standard torque limiter onto a new or existing drive without having to re-engineer the drive train.  

Acting like a mechanical circuit breaker, Autogard protects the drive train and reduces or eliminates downtime. The Autogard can be easily reset after tripping. By reducing the likelihood of gear drive damage during an overload, Autogard makes operations less costly over time. Combine Autogard with Falk V-Class Gearboxes to enhance your uptime and productivity. Request an expert consultation here


Autogard and V-Class in Mining/Ball & SAG Mills 

Learn more about the power of combining Autogard and V-Class in this case study:

Ryan Schuller-Rach

Ryan is the Commercial Operations Leader for Regal Rexnord's Industrial Powertrain team. He is a Professional Engineer in the state of Wisconsin and has been with Rexnord Power Transmission since 2011, where he has held leadership roles in new product development, product management, and engineering technical services. Ryan graduated from Bradley University with a Bachelor of Science in Mechanical Engineering and a Masters in Business Administration from Marquette University.