EM-126 | Hanging Rope Apparatus

Free-hanging cables and ropes are often used to support a structure, such as stay cables. On suspension bridges they are the load-bearing element of the structure. In many calculations the influence of the dead-weight of the cable can be ignored, because it is low compared to the other loads. In the case of overhead power lines, however, the dead-weight of the cable is relevant to the design of the pylons. A free-hanging cable under the influence of its own dead-weight is investigated. A roller chain serves as the cable, and is mounted on two ball bearing-supported chain wheels. The chain wheel units are fixed to a cross-arm. The spacing between the chain wheel axles can be adjusted horizontally and vertically. Weights can be attached to both ends of the chain. The maximum sag is measured using scaled rules, and can be compared with calculated values. The sag is the distance between the connecting line of the supports and the catenary (see also illustration: “Actual applied cable forces”).