Limit Switches
Limit switches are contact proximity sensor devices that consist of an actuator mechanically linked to a set of output contacts. When an object comes into contact with the actuator, the device operates the contacts to make or break an electrical connection.
Components of Limit Switch
Limit switches are made up of three key components.
Actuator Head
The actuator is the part of the switch that makes physical contact with the object. In some limit switches, the actuator is attached to an operating head that translates a rotary, linear, or perpendicular motion to open or close the electrical contacts of the switch.
Switch Body
The switch body is the component containing the electrical contact mechanism. The contacts within the body open or close the electrical circuit when the actuator is activated.
Receptacle/Terminals
Receptacles or terminals are components containing the terminal screws or screw/clamp assembly necessary for wiring purposes.
Types of Actuators
Limit switches are available with a wide range of actuator types. The type of actuator used can be determined by the mounting position, the force required, and the objects to be detected.
Rotary Lever
With lever actuators, a cam or plate hits the end of the lever arm, which in turn rotates a shaft and operates the contacts in the limit switch. The rotation may be spring returned (momentary) or maintained.
Plunger
Plunger types are best where short controlled machine movements are present or mounting space does not permit a lever type.
Cat Whisker or Coil Spring
Meanwhile, cat whisker or coil spring actuators are longer actuators with a coil wire that can be moved/bent in multiple directions. These are typically used in conveying applications to count objects as they pass by.
Forked
Forked actuators are used with maintained contacts and consist of two roller levers. One roller will trip the limit switch, and when the second is moved in the opposite direction, it will reset the limit switch.
Applications and Industries
There are several ways limit switches are used in industrial settings in New Zealand:
- Automation: Automation micro switches are engineered to respond to a small force. These switches feature an actuator, typically a small lever, which activates the switch upon being pressed. Known for their high precision, automation micro switches can detect even minor changes in force or position. This enables them to help control parameters within automated systems, including robotic arms, conveyor belts, and assembly lines.
- Industrial Manufacturing: Mechanical limit switches, such as micro switches, are frequently used as position or presence sensors within industrial systems. They operate electromechanically, meaning these switches are activated through physical contact with an adjustable actuator when an object comes into proximity. This enables them to help detect the position of machine components, monitor their speed, or manage their movement. They are commonly found in environments like assembly lines and conveyor systems. Meanwhile, optical limit switches are used in applications where precise control over valve positions is necessary, such as regulating the flow of liquids or gases, especially in high-temperature and dusty environments.
- Safety Mechanisms: Limit switches can also be used as safety interlocks to prevent machine parts from moving any further when a specific point is reached, enhancing workplace safety for operators. A good example of this is an automatic garage door. Without a limit switch that stops the door when it reaches the bottom rail, the door would keep moving downwards and eventually crash, causing serious damage.
How to Order Safety Limit Switches from RS?
Understanding the importance of limit switches in industrial settings is only part of the equation; knowing where to source reliable switches is equally crucial for seamless operations. RS New Zealand addresses this need with our extensive assortment, which includes compact mini switches and products with a wide range of voltage options from 12v to 690v. This variety ensures you can find dependable offerings that perfectly match your operational requirements.
Our products, which are affordably priced, are also sourced from trusted brands like Honeywell, Telemecanique Sensors, and our very own RS PRO, ensuring that you get quality and value with each purchase. Shop our selection of limit switches and other tools, such as electrical relays and din rail power supply, and take advantage of our free delivery service today.
For approved RS business account holders with a valid NZBN, enjoy free delivery on online orders over $40 (excluding GST) and offline orders over $80 (excluding GST). If you are using a private account or making a purchase as a guest, you can benefit from free delivery on all online and offline orders over $80 (excluding GST).
Delivery Information for New Zealand
Orders for items stocked locally in New Zealand or Australia placed before 5 pm NZT and 3 pm NZT, respectively, will be delivered the next working day.
While RS endeavours to deliver your limit switches and other items ordered on the following working day between 8 am and 5 pm local time, some items may require longer lead time. These include:
- Global Stock and Extended Range products.
- Orders containing hazardous materials.
- Products over 20kg, with a cubic weight exceeding 20kg, or longer than 1.5 metres.
Extended lead times may also apply to non-core products and deliveries to specific regional areas. For further information or to arrange consolidated delivery, please reach out to Customer Service.