Draw wires sensors

A draw wire sensor is a device designed to measure linear motion. Its operation is based on a spring‑loaded retraction mechanism, in which a steel cable drawn from the sensor drum follows the movement of the measured object. As the moving part attached to the end of the cable is displaced, the cable rotates the sensor drum and is smoothly retracted in accordance with the motion.

Draw wire sensors are particularly well suited for applications where the use of traditional linear sensors is challenging due to limited space, long measurement distances, or harsh environmental conditions.

In FSG draw wire sensor series, the measurement ranges vary by model from 1 meter up to 60 meters. Gefran’s draw wire sensors (GSF series), in turn, offer standardized measurement ranges between 1.8 and 12.5 meters, covering many typical industrial applications.

Draw wire sensors are available with both analog and digital output signals, enabling easy integration into a wide range of automation and control systems.

Most draw wire sensors are designed with durable aluminum or plastic housings, and for demanding operating environments, stainless steel versions are also available. In FSG’s premium and heavy‑duty sensor series, the typical protection classes are IP66 or IP67, ensuring reliable operation in dusty, humid, and mechanically demanding industrial conditions. In special versions—such as explosion‑proof designs or housings made of V4A stainless steel—the protection class can reach IP68 or IP69K, enabling use in extremely harsh environments and applications requiring resistance to high‑pressure washdown.

Many modern draw wires are also designed for safety-critical applications. For example, FSG’s premium and analog sensors are available in redundant versions that meet up to PLd and SIL2 safety levels.

FSG’s range of draw wire sensors covers several product series designed for different application requirements. The Basic series is the most compact option for short measuring distances (0–1.25 m) and uses a plastic cable. The Compact series offers a cost-effective solution with an aluminum housing and standard protection. The Premium series is designed for demanding industrial environments and long measuring ranges of up to 60 meters, featuring a steel cable and extensive interface options such as PROFINET and CAN bus, as well as optional ATEX protection.