Engineering Wonders of the World
Volume I

126 ENGINEERING WONDERS OF THE WORLD. must be allowed for, are shaped like an in- verted U, having vertical sides. The frames are set about 30 yards apart. Every 200 or 300 yards is a rigid frame, incapable of move- ment in any direction, whereas the inter- mediate frames rest on ball-and-socket bear- ings, and are able to rock in the direction of the axis of the line. This arrangement makes upper cross member and the vertical member are rectilinear on curves between supports, whereas the lower cross member with its rail-bearers follows the curve. The girder is braced in all directions. A carriage, about 40 feet long and 6 feet wide, is suspended from two two-wheeled bogies having wheels 35 inches in diameter. INTERIOR OF THE DOPPERSBERG STATION AT ELBERFELD. allowance for the expansion and contraction of the girders of the permanent way, which are provided with expansion joints half-way between every two fixed frames. The two wheel rails for the bogies from which, the carriages on the two tracks hang run along the outside edges of girders which, viewed from the end, have, roughly, the shape of an H turned on its side. The up- right member takes the vertical forces, and the cross members give lateral stiffness. The Track Girders. On each bogie is a 36 horse-power motor, which through spur gearing drives both of the track wheels. Hook-shaped frames , K , ,, Carriages. connect the bogies to the carriage. The clearance between the under part of the hook and the lower side of the track rail is so small—| inch—that the wheels cannot possibly jump from the rail. Should a wheel axle break, the bogie would fall —though a small height—and rest on longi- tudinal projections of the hook which nor- mally just clear the rail.