Abstract: A device for detecting the breakage of, and excessive tension in, the thread operating in knitting machinery, the device comprising a case, a first detection lever for detecting breakage of the thread, and a second detection lever for detecting excessive thread tension, both detection levers being pivotally mounted to the case. The second detection lever cooperates with a return spring attached at one end thereof to the lever and at the other end thereof to the case. The location of the points at which the spring is attached to the second detection lever and case respectively are such that the spring provides a force which resists the pivoted movement of the detection lever, such force varying by a small but uniform amount with the angle defined by the lever. The thread is applied to and supported by the second detection means. When the thread is subjected to excessive tension, the second detection lever pivots against the resisting force of the spring until it reaches an angle at which the thread escapes.