Piezoelectric actuator for magnetostrictive linear displacement measuring device

A position transducer of the type which comprises a housing, a magnetostrictive wire disposed within the housing and mechanically anchored at opposite head and foot ends and defining a position measurement range between said ends, a magnet displaceably mounted on the housing for linear displacement along the wire, and signal process means for producing a signal representative of the position of the magnet along the wire, wherein the improvement comprises:

• actuator means for imparting a torsional strain to the wire adjacent the head end, the actuator means comprising a piezoelectric crystal, clamping means frictionally holding said wire to said crystal, said clamping means including a first lower pad of elastomeric material between a base portion and said crystal, a second upper pad of elastomeric material and a removable clamp plate, and means for applying an actuation signal to the crystal to translate a surface of said crystal transverse to the linear axis of the wire thereby to twist the wire in the locale of the crystal.