I recently ran across an interesting article that explored some of the factors involved in selecting hydraulic cylinders. The article, entitled “3 Steps to Choosing the Right Hydraulic Cylinder” was very informative and helpful. But what if you need a “smart cylinder”, i.e. a cylinder that can provide absolute position feedback? Just as it’s important to select the proper cylinder to match the mechanical requirements of your application, it’s also important to select the right sensor to meet the electrical requirements.
So, to that end, I’d like to piggyback on the cylinder selection article with this one, which will look at 3 steps to choosing the right in-cylinder position sensor. In particular, I’ll be talking about rod-type magnetostrictive linear position sensors that are designed to be installed into industrial hydraulic cylinders to provide absolute position feedback.
Before we get to step 1, let’s talk about the cylinder itself. So-called smart cylinders are typically prepped by the cylinder manufacturer to accept a magnetostrictive position transducer. Prepping consists of gun drilling the cylinder rod, machining a port on the endcap, and installing a magnet on the face of the piston. For more information about smart cylinders, consult with your cylinder supplier.
Step 1 – Choose the Required Stroke Length
The stroke length of the position sensor usually matches the stroke length of the cylinder. When specifying a position sensor, you usually call out the working electrical stroke. Although the overall physical length of the sensor is going to be longer than the working electrical stroke, this is usually not a concern because the cylinder manufacturer accounts for this added length when prepping the cylinder.