Thursday, 31 May 2018

How To Use An External Limit Switch Kit With A Linear Actuator

Linear actuators come in many different stroke lengths to suit a variety of needs. That said, you may find yourself needing to customize your linear actuator by reducing the stroke. Usually, the simplest and fastest way to achieve this is by installing a linear actuator limit switch kit.


What is a linear actuator limit switch kit?


By default, many linear actuators have a means to either stop the actuator when it reaches its end of stroke, or prevent it from damaging itself. The most common ways of accomplishing this are by adding stall protection, to prevent the device from trying to push against its end-limit until it burns itself out, or an internal limit switch. On devices with limit switches, the moving mechanism within the actuator physically contacts a switch within the actuator that cuts power to the device.


linear actuator limit switch kit
Actuonix Limit Switch Kit


Some larger actuators have adjustable end limit switches. With Actuonix devices, the tiny size of the actuator makes this impossible. This is where an external limit switch kit comes in.

A limit switch kit is a set of two simple switches that when wired into your actuator's control circuit, replace the function of the internal switches. This kit is mounted externally and requires that the moving part of your mechanism actually makes contact with the switch on the retraction and/or extension strokes.

It can be the rod or block of the actuator itself, or any moving part of your mechanism that contacts the switch, your choice.


Pretty simple right?

Using one of these kits, you can customize the stroke of your actuator to whatever you want below the maximum, factory stroke of your device.



How do limit switches work?


External limit switches are used to break an electrical circuit when activated. Our limit switches have a sprung bar that when depressed, breaks the electrical connection that is driving the actuator, causing it to stop. Using a diode in the circuit allows the actuator to move in the opposite direction.

There are many different types of limit switches out there in a variety of sizes to accommodate everything from micro linear actuators to heavy duty linear actuators.



Pros and cons of installing an external limit switch kit


Pros:

  • Makes it simple to customize your actuator's stroke below the factory setting
  • Much cheaper than ordering a custom linear actuator (which must be done at higher quantities)
  • Simple to wire up and effective

Cons:
  • It increases the complexity of your project and may make your wiring a little more messyTakes a little more time to set up than just plugging your actuator in
  • Makes your design slightly more complex

Which actuators are compatible with a limit switch kit?


You can install limit switches on any -S or -P Actuonix linear actuator. The -P series does not have internal switches, instead it has stall protection when used with the LAC board. This means that if you're not using it with an LAC it's possible to burn the device out if you run it to it's end limit and continue to apply power.

If you're planning on using a -P actuator without an LAC, it's a good idea to use a limit switch kit as well to avoid damaging the actuator.



How To Install A Linear Actuator Limit Switch Kit


A limit switch kit must be wired into the control circuit of your actuator. Here are some things that you will need:

Parts:

Actuonix -S series or -P series micro linear actuator
External limit switch kit
Control switch of your choice
Power source
Heat shrink tubing (if you're soldering the connections)


Tools:

Wire stripper
Soldering iron or connectors with crimping tool

All you need to do is simply wire the limit switches into your control circuit following the wiring diagram below.


how to install limit switches


Summary


Installing an external limit switch kit is a cheap and easy way to build a custom linear motion solution that meets your exact needs. Our kit comes with almost everything that you will need to install your kit including two switches and diodes.

Have a question? Feel free to reach out to our sales team. We are in the office Monday through Friday from 7:30am to 2:30pm Pacific Standard Time excluding Canadian and provincial holidays. If you leave a message or email outside of those hours we will get back to you the next business day.


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