Abstract: The tensiometer is designed to measure the tension in cables from extremely heavy loads as might occur in large cranes and in oil well rigs. The tensiometer utilizes a pair of spaced tandem pulleys bearing against spaced points on the cable and a central pulley engaging an opposite point intermediate the spaced points so as to force the cable laterally. The tension in the cable tends to straighten the cable and thus exert a load on the central pulley and by measuring this load, a force is developed constituting a function of tension in the cable. The central pulley is removably mounted from the frame structure on an arm. One end of this arm is thus arranged to be pivoted to the frame structure after the cable has been received against the first and second pulleys.