Does your facility deal with critical infrastructure/ equipment with rotating parts? If you answered “yes,” it is vital to take every caution to help keep the equipment secure. These critical facilities or equipment can fail or even break from a single incidence. Such incidents happen when rotating components experience torque beyond what they are made to handle (mechanical overload). This excess force can result in breakdown to the facility, plus related accessories, such as couplings, shafts, and gearings. To avoid or reduce this danger, you need to use torque limiters.

Keep reading as we dig deeper into torque limiters to determine what they are, how they work and areas of application in industrial facilities.

What is a Torque Limiter?

A torque limiter is an automatic device designed to help protect mechanical equipment from damage caused by torque overload. They are also deployed to prevent crashes and jams in industrial machines. The limiter may limit the torque by slipping or uncoupling the load entirely.

Torque limiters can work independently or combined with other sensors to help increase efficiency. At times, you might find the limiters being referred to as overload clutches.

During normal operations (when there is no torque overload), the limiter uses a friction disc to transmit torque from the driving shaft to the driven member, such as pulleys and sprockets. When the torque limit is exceeded, the friction force is no longer strong enough to transmit the torque, and the driven member slips between the friction discs. After the torque level goes down to the recommended rates, the friction plates resume transmitting rotating motion automatically.

Types of Torque Limiters

Torque limiters can be classified into two; disconnect type (this category uncouples the drive so that little or no residual torque gets to the load) and torque limiting type (this one reduces the torque getting through to the load through slipping). Let's look at them closer:

Disconnect Torque Limiters

• Shear pin torque limiter: This type of limiter works by sacrificing one of the mechanical components, the pin, to help disconnect the shafts when the torque limit is exceeded.
• Synchronous magnetic torque limiter: This torque limiter utilizes permanent magnets fitted on each shaft (driven and driving) and also features an air gap. Although very fast-acting, they experience more backlash compared to shear pin torque limiter types.

Torque Limiting Types

• Friction plates: In the case of over-torque, the fiction plates slip. A good example is the spool fishing reel, where the slipping torque is set with a hand nut to allow the reel to turn and the line to unwind before it can break when the fish starts pulling.
• Magnetic Particles: This type of clutch can also be used as a torque limiter. The torque setting approximates a sort of linear relationship with the current that is running through the windings. This can be set depending on your equipment needs.

The above four torque limiters are the most common today. Others that you might want to know about include, ball detent, and magnetic hysteresis.

The Main Applications of Torque Limiters

As we indicated earlier, torque limiters can be used to protect any machinery that has rotating components. Industries that commonly use torque limiters include:

• Machining and equipment manufacturing industries
• Printing and converting industries.
• Forest products.
• Textile manufacturing.
• Specific applications include conveyors, generators, motors, and gearboxes.

Torque limiters are very important when you have facilities or equipment that are unable to absorb full torque from the driving shafts. By disconnecting the critical facility or limiting the torque, the torque limiter reduces the risk of equipment damage, expensive downtime, and regular replacement. Remember to also ensure the torque limiter plus all other machinery, especially the motors, are maintained in top condition all the time.