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TANK LOCOMOTIVES FOR THE BROOKLYN BRIDGE.
Engineering News, June 13, 1895

On the Brooklyn Bridge cable railway tank locomotives are used for switching the trains from the incoming to the outgoing tracks, and also for hauling the trains at night (from 1 a. m. to 5 a.m.), when the cable driving plant is stopped for inspection and overhauling. For about ten years all the engines were of the four-wheel type, with saddle tanks, the weight increasing from 10 tons in 1883 to about 22 tons in 1893, and six of these heavier engines are still in use, As these engines had 33-in. wheels and 6 ft. wheel-base, and rapidly wore out the rails and wheels at the switches and the extremely sharp curves (100 ft. radius) over which they have to pass, and as it required two of the engines to haul a; train of three cars over the bridge (the maximum grade being 3¾), it was decided to try a heavier and more powerful engine. A "double-end" type was adopted, and the first was built in 1893 by the Baldwin Locomotive Works (Eng. News, Dec. 7, 1893). It has four 42-in. driving wheels, with 5 ft. driving wheel-base, and has a pony truck at each end, making the total wheel-base 17 ft. 7 ins. The weight is 68,000 lbs., with 53,000 lbs. on the driving wheels. On dry rails and under favorable conditions of track it can haul a train of four partially, or three fully, loaded cars up the maximum grade at the speed of the cable trains, or 10.3 miles per hour, this load being equivalent to about 85 to 100 tons, the heaviest cars weighing 20 tons empty.

Two more engines of the same type, but somewhat larger and heavier, have recently been built by H. K. Porter & Co., of Pittsburgh, Pa., and one of these is shown in the accompanying cut., These engines can haul six empty cars or four loaded cars in regular service. The bank capacity is increased by extending the saddle tank over the smoke-box, and the smokestack is made wider at the top than at the base, instead of being a cylindrical stack, as in the other engines. The engine is fitted with the vacuum brake, the same as the cars, and the Lappin flange-bearing brake-shoes of 50% hardness are used. The driving wheel tires are 3 ins. thick, and the truck wheel tires 2½ ins. thick, all 5½ ins. wide and flanged. The coiled bearing springs were specified to be of 7/8 in. rods, and the flat springs to have not less than 14 leaves 3½ ins. wide for the, driving wheels and 8 leaves 2¼ ins. wide for the trucks. The three spark arrester plates are 1/8-in. thick, with holes 1½ x 3-16 in., and there is also a steel wire netting. The feed is supplied by a Korting injector and a force pump, each capable of supplying the full amount of water. A boiler compound pot is also attached, and lubrication is provided for by two Detroit automatic sight-feed lubricators in the cab. The discharge from the brake ejector is muffled, two 2½-in. Coale mufflers being fitted.

The specifications make the following provisions as to quality and tests of material: Boiler plates to be of open-hearth steel, with a tensile strength (unannealed) of 55,000 to 65,000 lbs. per sq. in., and an elongation of not less than 20% in 8 ins. Stay-bolt iron to be capable of bending double both ways without crack or flaw. The tubes to be rolled strictly to gauge throughout their length, to show a perfect weld, be free from pitholes and other imperfections, and to be expanded when fitted into place without crack or flaw, while a 2-in. length must withstand flatting closely down under the hammer without appearance of fracture. The iron for stay-bolts and tubes must have a tensile strength of 50,000 lbs. per sq. in., and an elongation of 25% in 8 ins. The flues to be tested with a hydraulic pressure of 500 lbs. per sq. in., and copper and brass pipes 300 lbs. per sq. in. Springs to be oil tempered, and to sustain without set a weight equal to 1½ times the extreme working load. The boiler to be subjected to a test of 240 lbs. per sq. in. by hydraulic pressure, and 185 lbs. per sq. in. under its own steam. We give below, in our standard form, the list of dimensions and particulars of the engine:




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