Strain-responsive visual indicator

A strain-responsive visual indicator comprising a pair of overlapping members adapted to be mounted to a substrate such that strain in the substrate causes relative movement between those members;

• the proximal member comprising a set of windows alternating with separators arranged in the direction of said relative movement;
• the distal member comprising or being adapted to reveal indicia elements of at least two visually distinguishable types alternating in the direction of said relative movement;
• and said windows, separators and indicia elements being configured such that in a first relative position of said members a plurality of the windows of the proximal member register with indicia elements of a first said type and in a second relative position of said members said plurality of windows register with indicia elements of a second said type;
• and wherein said windows and indicia elements are inclined relative to each other in said direction of relative movement and means are provided for restricting the view of said members to a selectable transverse portion thereof.

A strain-responsive visual indicator comprising a plurality of pairs of overlapping members adapted to be mounted to a substrate such that strain in the substrate causes relative movement between each said pair;

• the proximal member of each said pair comprising a set of windows alternating with separators arranged in the direction of said relative movement;
• the distal member of each said pair comprising or being adapted to reveal indicia elements of at least two visually distinguishable types alternating in the direction of said relative movement;
• and said windows, separators and indicia elements of each said pair being configured such that in a first relative position of the respective pair a plurality of the windows of the respective proximal member register with indicia elements of a respective first said type and in a second relative position of the respective pair said plurality of windows register with indicia elements of a respective second said type;
• and wherein the windows and indicia elements of the respective said pairs are of different respective pitch.

A strain-responsive visual indicator comprising a pair of overlapping members adapted to be mounted to a substrate such that strain in the substrate causes relative movement between those members;

• the proximal member comprising a set of windows alternating with separators arranged in the direction of said relative movement;
• the distal member comprising or being adapted to reveal indicia elements of at least two visually distinguishable types alternating in the direction of said relative movement;
• and said windows, separators and indicia elements being configured such that in a first relative position of said members a plurality of the windows of the proximal member register with indicia elements of a first said type and in a second relative position of said members said plurality of windows register with indicia elements of a second said type;
• and further comprising means for retaining said members in the position of maximum relative displacement attained over a period of use.