Thinking Outside the Cylinder

In a previous entry, I discussed how linear position sensors are used with hydraulic cylinders to provide continuous position feedback.  While this is certainly one of the most common ways linear position sensors are used, there are many applications for linear position sensors that either don’t involve a hydraulic cylinder at all, or that involve a cylinder only indirectly.

Linear position sensors for external use (not installed into a hydraulic cylinder) offer some very tangible benefits when compared to in-cylinder sensors.  Let’s explore a few of those benefits:

1.  Cost:  A typical externally mounted linear position sensor is significantly less expensive compared to a comparable in-cylinder sensor.  And the cost of the sensor itself doesn’t even tell the whole story.  The cost of the cylinder preparation, such as gun-drilling the cylinder rod and machining the port into which the transducer will be installed, must also be taken into account.

Typical external-mount linear position transducers, shown with floating magnet (left), and mechanically linked captive magnet (right)

2.  Mounting Flexibility:  Given the wide variety of mechanical housing styles available, an externally mounted position sensor can be installed in a variety of places, and in a variety of ways.  Using either a mechanical linkage to the moving part of a machine, or perhaps a bracket with a so-called “floating magnet”, possible installation options are limited only by the mechanical engineer’s creativity.

, 3.  Ease of Maintenance:  If an-cylinder sensor requires maintenance or replacement, it can sometimes involve de-pressuring the hydraulic system, removing the sensor (possibly spilling oil in the process), and installing a new sensor in its place.  And this is assuming the cylinder is in an accessible location.  Generally speaking, an externally mounted sensor is much more accessible, and easier to repair or replace.

4.  Retrofitting:  Perhaps the biggest advantage offered by an externally mounted position sensor is the ability to easily retrofit an existing machine without the need to replace the existing prime mover (hydraulic or pneumatic cylinder, electric motor, etc.) with one with integrated position feedback.

For more information on linear feedback sensors, both in-cylinder and externally mounted types, click here.

One Response to Thinking Outside the Cylinder

  1. Pingback: The True Cost of Low-Cost « SensorTech

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