A load-indicating device, e.g. an overload detector adapted to be placed between a load and a hoisting cable of a crane, consists of an annular member (I) of a high tensile steel, which is stressed by the load along a given axis - within its elastic limit - and is provided with an electric displacement transducer (III) placed between the portions of the annular member (I) with its displacement axis at right angles to the load vector (F, F′). The member (I) is elongated in proportion to the load acting on it, whereby the distance between the portions associated with the transducer (III) decreases, thus changing the output from the transducer (III) which obtains an input from a voltage source. This output is fed into an electric circuit (IV) adapted to indicate the actual weight of the load and/or to produce a warning signal and/or to stop the machinery at a dangerous overload.