Basic information about torque limiters
Q: What is a torque limiter?
A: A torque limiter is a device that interrupts the transmission of force to the output side when torque exceeding the set (rated) value is applied. It is used to protect equipment and components such as motors and gears from damage due to overload. Depending on the application, it may be used in combination with a clutch mechanism.
Q: What is the structure of a torque limiter?
A: Torque limiters utilize either friction resistance or magnetic force.
- Friction disc (Contact type):
Transmission torque is generated by the resistance of a friction disc pressed by a spring, and slippage occurs when the set value is exceeded. - Coil spring friction type:
Spring is press-fitted around the sleeve’s outer circumference. Power is transmitted with a load applied to the spring’s hook end in a direction that expands the inner diameter. Slip occurs when the set value is exceeded. - Ball detent type (Contact type):
A ball is held in a recess. During overload, the ball disengages, interrupting torque transmission. - Magnetic type (Non-contact type):
Torque is generated using magnetic force. Slip occurs when torque exceeds the set value.We handle two types: the coil spring friction type and the magnetic type.
Usage environment
Q: Are temperature fluctuations and humidity a factor?
A: Depending on the characteristics of the lubricants and friction materials, torque values may fluctuate in extreme temperature environments. Magnetic type torque limiters tend to have higher torque in low-temperature environments and lower torque in high-temperature environments. If the operating environment is harsh, please contact us regarding specifications with weather and moisture resistance.
Durability
Q: Are there any guidelines regarding service life or maintenance?
A: While the product has a long service life under normal operating conditions, repeated operation or frequent high-load conditions will accelerate wear and deterioration. We recommend performing regular torque checks and visual inspections.
Additionally, please check the product specifications, which clearly state the durability for continuous unidirectional rotation.
Q: What is the maximum operating speed?
A: The service life of a torque limiter is significantly influenced by a combination of factors, including rotational speed, operating mode (continuous or intermittent operation, forward/reverse rotation, etc.), and ambient temperature. Therefore, we do not specify a uniform permissible rotational speed. Please refer to the durability test results under unidirectional continuous rotation conditions specified in the product specifications. We ask that you conduct your own evaluation tests to determine suitability for your equipment and to establish the permissible rotational speed.
Applications
Q: Where are torque limiters used?
A: They are used in areas such as paper feeding sections, banknote transport mechanisms, and gear trains, where excessive torque can lead to failures or paper jams. For example, they help prevent machine damage caused by foreign object entrapment or transport jams.
Typical application examples:
- Paper feed roller drive units in printers
- Banknote feeding mechanisms in cash handling machines
- General industrial equipment
- Precision parts transfer devices
- Camera shutter actuation control units
- Compact medical devices
Functions and performance
Q: What is the basic operating principle of a torque limiter?
A: The basic operation is as follows:
- Normal operation:
Torque is transmitted from the input shaft to the output shaft.
As long as the torque remains below the set value, rotation is transmitted normally. - Overload condition:
When the torque exceeds the preset level, frictional force or magnetic force can no longer sustain the load, causing the output shaft to slip (idle). This interrupts and controls torque transmission, thereby preventing damage to the equipment. - Reset:
Once the overload condition is removed, the torque limiter either automatically resumes torque transmission (automatic reset type) or requires manual reset (manual reset type).
Q: Can the torque setting be adjusted?
A: Generally, the torque is fixed at the value set at the time of shipment. However, depending on the model, some types allow adjustment.
Q: Is a restart required after the torque limiter slips?
A: Torque limiters are typically of the automatic reset type, which automatically resume torque transmission after slipping.
However, there are also manual reset types that require repositioning. Selection should be based on the application. TOK adopts the automatic reset type.
Q: Why does slipping occur at a torque higher than the set value?
A: If radial or axial loads are applied, additional friction (sliding resistance) is generated the torque limiter. As a result, the actual slipping torque may become higher than the set value.
When installing the torque limiter, care must be taken to avoid applying direct loads.
If slipping occurs at a higher torque even without any radial or axial load, the torque limiter may be malfunctioning. In such cases, please feel free to contact our sales representative.
Q: Is the torque listed in the catalog the torque at which slipping starts from a non-slip condition?
A: Yes, that is correct. It refers to the starting torque at which slipping begins from a non-slip condition.
Others
Q: Can I purchase samples or small quantities?
A: For quotations and purchases, please contact your distributor or trading company.
If you have any questions, please feel free to contact our sales representative.
