MRO Magazine

Ultra-precise spring-loaded LVDT linear position sensors

Pneumatic devices are used in material handling and processing systems to push, pull, lift, and close and open doors. They are also used to hold and remove materials and position pieces for manufacturing. Compressed air is used to move a pneumatic cylinder. When compressed air enters the base of a pneumatic cylinder, it pushes on the piston and makes the piston rod move out. Air on the other side of the piston is vented into the atmosphere. A pneumatic cylinder simply converts air pressure into linear motion. To ensure proper operation, pneumatic cylinders employ Linear Variable Displacement Transducers (LVDTs) to measure range of motion. A spring-loaded LVDT is typically installed on the cylinder tip area to make measurements when the cylinder is fully extended. 


December 1, 2015
By PEM Magazine

Macro Sensors offers the BBP Series of Air Extended, Spring-Loaded LVDT Position Sensors for these types of applications. The position sensors features a probe that moves out and makes measurements only near the very end of the probe movement when it is almost fully extended and then retracts so the probe gets out of the way of damage.

These 3/8” inch diameter pencil type gaging probes measure the position of a target surface with an unusually high degree of accuracy. Because probe measurement is made only near the very end of the probe movement, such as when it is almost all the way extended, a short range LVDT can be used to get high resolution. In this configuration, a short range LVDT linear position sensor (0.050” to 0.125”) that measures a short distance can be used to get highest resolution as the full range of the cylinder stroke often does not have to be measured. 

Macro Sensors has found that many users do not want to measure the total range of the cylinder; they just need to get the probe out of the way of damage.  In these applications, a one or two-inch stroke cylinder can use a short range spring-loaded LVDT to measure a nominal plus or minus one millimetre at full probe extension before the probe retracts. And because the LVDT does retract when not making measurement, the cylinder is retracted to get the ram and the gaging tip out of the way for manually loading parts, parts coming in from transfer lines, heavy parts getting banged and bounced in a foundry, etc.

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