TOK Torque Limiter web site

A torque limiter is an overload protection mechanism incorporated between the shaft and output side components to protect against overloading of the output section components when a certain torque is exceeded. When an overload is applied to conveyance devices or measuring instruments, the internal parts slip, preventing malfunctions and protecting the safety of the user. There are many other ways to utilize torque limiters that will benefit you.

In this article, we introduce how to connect torque limiters, which are overload protection mechanisms, and how they can be utilized.

Please check our product list if you know which torque limiter you need.

How to connect a torque limiter

First, you need a shaft to which you connect the torque limiter. This shaft must have a pin to connect it to the torque limiter, and the pin should be a parallel pin or a spring pin. Then, you insert the shaft so that the pin fits into the groove of the torque limiter and connect the output part to the convex part on the torque limiter. Note that if the torque limiter and output component are attached directly to the motor shaft, the torque limiter will not be effective, so separate shafts must be used for the motor and output component.
If the load on the output side is less than the torque limiter’s default torque, the inside of the torque limiter will transmit power to the output side without slipping. When you put an overloaded condition by holding the output side by hand, you will find that the torque limiter will slip inside and shut off the power.

You can check the connection procedure and actual motion in this video.

How to utilize a torque limiter

The first way to utilize torque limiters is to protect against overloading of the conveyance device. It slips when the specified torque is exceeded, preventing damage to equipment, preventing expensive equipment from breaking down, and extending the life of equipment. Torque limiters are often used in conveyance devices, but they can be also used in high precision measuring instruments. When the measuring instrument is pressed against the object, it destroys the tip of the measuring element, so that it slips and prevents further torque from being applied when more than the certain torque is applied. In particular, the magnetic type torque limiter is characterized by its high precision and quiet functioning without any unusual noise.
Also, it can be used as a free stop hinge. Since the torque limiter will not slip unless a certain torque is reached, it can be stopped at a desired angle by applying less torque than the specified torque.

Main usages

〇Pharmaceutical packaging machines
A pharmaceutical packaging machine is a machine that automatically performs the entire process of bagging medicines one by one and scanning them for errors. After this machine automatically packs the medicines into bags, labels with the necessary patient information must be attached to each bag, but the uneven surface of the bags prevents the labels from being attached properly. However, by selecting and installing a torque limiter suitable for the specifications required by the machine from a wide range of torque lineups, the labeling problem can be eliminated.

〇Electric screwdriver
When a torque limiter is mounted on an electric screwdriver, it helps to tighten screws without putting a strain on the object.
Without a torque limiter, the torque of the motor will continue to be transmitted to the screw even after the screw has been tightened, resulting in damage to the object. However, if a torque limiter is installed, it slips even if excessive torque is generated, so the motor torque is not excessively transmitted to the screw and can be installed without problems. You can check the motion with a gif video here.

〇Cash machines
Torque limiters are also used in ATMs and other cash machines. ATMs equipped with a torque limiter prevent the roller on the wound up side from turning too much when the motor winds up the bill, so that it is taut and not bent. The balance between the torque of the motor on the wind up side and the torque of the torque limiter is important, and the magnetic type torque limiter, in particular, is highly accurate and has a wide range of torque lineups, so you can select the right one for the strength of your motor.

Summary of How to use a torque limiter | Overload protection mechanism

Torque limiters can be used to retrofit an overload protection function to motors even if they do not have it. This is effective when you want to make the size of the motor foundation smaller. Torque limiters also have unlimited possibilities, such as being used not only for motors but also for free stopping hinges.
Since it is necessary to select a torque limiter according to the required torque, please feel free to contact us using this form if you have any questions.