GB233158A - - Google Patents

Abstract

233,158. Ollert, G. May 23, 1924. Girders.-To balance the stresses set up in loaded lattice-work structures, extension measuring devices are connected to some of the bars of the structure and on alteration in length of the said bars actuate driving devices which alter the length of other bars of the structure so that the extension measuring devices return to their zero position. As applied to a suspension bridge, a rod a, Figs. 1 and 3, is fixed at its end b to a member c and when displaced relatively to the member c, due to loading or heat rotates the switch lever of a controller k to switch on a motor m, Fig. 2, which alterrs the length of the members t so as to restore the stresses in the member c to their original value, whereupon the switch lever of the controller cuts out the motor m. Wedge, chain or other driving devices may be used instead of that shown in Fig. 2, while the girder may be loaded initially to any desired degree. The devices may be used in cases of overloading due to ground subsidence.