. Electric railway journal . Plan. Side Elevation boom located at drawbridge and designed to stop street cars and automobiles 506 ELECTRIC RAILWAY JOURNAL [Vol. XLIX, No. 11 which this requires is provided by having the forked endmade of 3-in. x 4-in. x %-in. angles. The boom weighs1000 lb. and the two posts with counterweights 3000 lb.,making a total of 4000 lb. which must be put in motionwhen struck by a machine. The boom can spring 18 breaking and the tires furnish additional cush-ion, so that the rolling motion should take place withoutdamage. The resistance then increases, with
. Electric railway journal . Plan. Side Elevation boom located at drawbridge and designed to stop street cars and automobiles 506 ELECTRIC RAILWAY JOURNAL [Vol. XLIX, No. 11 which this requires is provided by having the forked endmade of 3-in. x 4-in. x %-in. angles. The boom weighs1000 lb. and the two posts with counterweights 3000 lb.,making a total of 4000 lb. which must be put in motionwhen struck by a machine. The boom can spring 18 breaking and the tires furnish additional cush-ion, so that the rolling motion should take place withoutdamage. The resistance then increases, with the changeto sliding friction, and the stopping action is still furtheraugmented when it becomes necessary to lift the boomand posts a distance of 2 ft. vertically in the last 5 ft. oftravel. There would still be left the 18-in. deflection inthe boom. The gate is designed to stop a 4000-lb. ma-chine going at 30 without injury to its occupants. Movable Switch for Passing Trolley Wires When the boom is raised it must pass th
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