Wire drawn linear position transducers, also known as string pots,
string encoders or yoyo pots are devices that detect and measure linear position
by using a flexible wire and a spring loaded spool.
The transducer is mounted onto any fixed surface and the flexible wire attached
to the movable target object. When the target object moves, the wire is
extracted from the transducer, which in turn generates an electrical signal proportional
to the length of wire extracted from the transducer. This signal is then sent
to a panel meter, PLC or data logger.
Wire drawn transducers consist of four main parts: measuring wire, spool,
spring and rotational sensor.
The stainless steel wire inside the transducer's housing is wound on a
precisely machined constant diameter cylindrical spool that turns as the
measuring wire is extracted and retracted. The wire tension is maintained by
coupling a spring to the spool, which in turn is coupled to the shaft of a
rotational sensor (an encoder or potentiometer). The spool and sensor shafts
rotate as the transducer's wire extends along with the moving target object,
with the rotating shaft generating the electrical signal output. An integral
dust wiper ensures the wire rope stays clear of debris as it is extracted and
UniMeasure offers a choice of commonly used industry-standard output
signals: Potentiometric (Voltage Divider); 0...10 Volts DC; 4...20 mA (2-wire);
0...20 mA (3-wire); Incremental Encoder (Quadrature).
Wire drawn linear position transducers are designed as a simple solution
to measure the position and movement of the target object. Easily installed,
the transducers can be positioned in tight or difficult to access areas without
requiring perfectly parallel alignment. Compared to other linear position
sensing solutions, wire drawn transducers tend to be more cost-effective.
UniMeasure wire drawn linear position transducers deliver excellent
linearity and repeatability at full scale, making them perfect for a wide
variety of applications such as industrial automation, high-tech medical
devices, structural and locomotive testing, and hydraulic cylinder control
among many others. Measuring ranges in the UniMeasure devices are available
from 0-50mm, all the way up to 0-50.8m.
UniMeasure wire drawn transducers are available in Australia from ADM Instrument Engineering .