The history behind the Pressductor transducer

How it all started
In 1953, Orvar Dahle, a researcher/inventor working for ABB (then ASEA), developed a transducer for shaft torque measurement, called the Torductor. It was based on the effects of torsion stresses on a magnetic field in the shaft. He was asked to apply similar principles in solving this new problem.
The first attempt (shown right) was a piece of transformer sheet with four holes located symmetrically on the diagonals and some primary and secondary turns of wire, at right angles to each other, through the holes. With a few amperes (50 Hz) in the primary, a small signal (10 mV) was obtained in the secondary by pressing the plate edgewise between two fingers. A promising start indeed!

The first orders
Naturally, for larger loads it was necessary to distribute the load over a number of sheets. To avoid buckling, these sheets had to be bonded together. In the case of the rolling mill at Surahammars Bruk, the space occupied vertically had to be minimized. Which is why multiple stampings were used, bonded together to form a rectangular block, allowing for a uniform load distribution. Shown right is one of two original Pressductor transducers (designed to handle 1,200 metric tons) - the starting point of Pressductor technology.

The development of the Pressductor transducer coincided with the advent of automation in the steel industry. The first major order, 12 Pressductor transducers, at 1,600 metric tons each, came from General Electric and their Geneva Steel Works, a few miles south of Salt Lake City. Experience derived from this order led to the development of a smaller load cell. Indeed, the Pressductor transducer (photo below), became the market standard with more than 10,000 deliveries over four decades.