Feedback options abound for pneumatic cylinders

摘要

A big difference between pneumatic cylinders and their hydraulic counterparts is that pneumatic cylinders usually have a barrel constructed of aluminum or some other non-ferrous alloy. This allows a magnet to be embedded within the piston so that the location of the piston can be detected through the barrel wall. With most hydraulic cylinders, though, the steel barrel makes this impractical. Potentiometers, linear displacement transducers (LDTs), reed switches, and Hall effect sensors all can provide electronic feedback of piston position in pneumatic cylinders. But there are circumstances where some should be used and others should not. If you only need to know when the piston reaches either end of its stroke, or a specific point along its stroke, then discrete switches provide the most practical solution. However, if continuous feedback is required for closed-loop positioning, then an LDT should be considered.