Locomotives with Trailing Bogies.

New designs of locomotives for American Railways are continually being made to meet changing conditions and developments (says “The Engineer,” 15/1/26). The increasing size of fire-boxes and the consequent great overhang and weight at the rear end led to the introduction of two-wheel trailing bogies several years ago, and this arrangement is practically universal on modern engines. With further increase in size and weight of locomotives, the weight on the trailing axle has become so great that, in combination with heavily loaded driving axles, the engines were very severe on the track, in spite of flexibility in taking curves. To meet this condition, four-wheel trailing bogies are being introduced and the Texas and Pacific Railway has recently put in service some ten-coupled engines of the 2-10-4 class, with the additional feature of a booster or independent engine geared to the rear axle of the bogie. The front cross frame of the bogie has an attachment for a pin connection in a transverse casting between the main frames. These engines, using oil fuel, can handle trains of 3,000 gross tons on divisions 200 and 270 miles in length, having ruling gradients of 1 in 66 and curves of 286 feet radius. The 63 in. driving wheels carry 300,000 lbs. or nearly 27 tons per axle, and the total weight of the engine is about 220 tons. The boiler, 8 ft. in diameter, carries 250 lb. pressure and has a radial stayed fire box, 12 1/2 ft. by 8 ft., with thermosyphon partitions carrying the brick arch.