[1] With In-cylinder Linear Displacement Transducers (LDTs), the hydraulic cylinder’s piston rod must be bored through its center to accommodate certain elements of the LDT — usually the waveguide tube of a magnetostrictive transducer.
[2] The machining and additional production steps associated with “gun drilling” the piston rod can add cost to the finished cylinder.
Magnetostrictive LDTs provide extremely high accuracy, down to one micron.
[3] External linear displacement transducers (LDTs) eliminate the need for a hollow hydraulic cylinder rod.
This magnetic field provides a locating signal to an external sensor.