Page:Popular Science Monthly Volume 89.djvu/69

 Popular Science Monthly

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��with is one of the most effective systems ever devised. It is in use at three points along the subway route in New York city. It has made possible the employment of huge fifteen-ton motor-tractor and trailer units and has speeded up the entire work of getting the excavated material out of the ground.

The system consists of an elevated platform set up on wooden bents on opposite sides of the street directly adjacent to the shaft Icatling down into the cut, an electric crane on top of this platform, and a double-decked stand on the street beneath it with an adjustable draw- bridge pivoted at one end to a per- manent bum- per to which

���SIX EMPTY CARS RUN OFF TRACTOR BY GRAVITY BRIDGE LOWERED AS ' SHOWN

��buckets are rolled down on it by gravity. The free end of the drawbridge is then raised to a level with the top of the double-decked platform and the loaded buckets run down it on tracks on to the trailer, which is then ready to leave ior the dump.

This entire operation takes five min- utes. By the old method it took twenty-five minutes. The large saving has been made i)\' having the load ready when the vehicle returns to the platform. The use of buckets with wheels has made possible the quick loading on the surface. They have also eliminated the congestion at the shaft bottom when ordinary buckets loaded on mine flat-- cars were used because these, when empty, had to be kept near the bottom of the shaft until an empty bucket was lowered from the motor \ehicle, mean- time held idle. The new system has reduced danger to a minimum and no accidents have yet been directly attributable to it. Thus speed and safety have been combined in this newest method of subway excavation.

���. ^ FOR GUIDANCE M BACKING UP

��TRAILER WITM 6 CARS 2 ROWS 3 IN A ROW

��MOTOR TRACTOR

��Only five minutes are needed to carry the loaded buckets from the cut to an overhead plat- form and load them on to a motor-truck

��the motor-trailers are backed. The buckets used are mounted on wheels. They are loaded in the cut and then moved on tracks to the foot of the shaft where they are picked up by the electric crane and hoisted one at a time and deposited on tracks on top of the double- decked platform. By the time six of the loaded buckets are thus placed, the tractor unit has returned from the dump with its load of six cmiit\' buckets, which arc carried on tracks on the trailer. After the trailer has been backed up to the bumper, the adjustable drawbridge is tilted from the top of the bumiwr to the level of the lower platform, and the

��A Workshop on Every Farm ACCORDING to one of the heads of S\ a western agricultural college a. source of economy that has been neglec- ted in the past is the upkeep of farm tools and implements. To overcome this depreciation a workshop should be erected. It need not be large, but sufficiently roomy to allow for a work- bench, a stove, and a certain amount of floor space where the machinerA' or tools ma>' be repaired or taken apart and re- assembled. This will provide a proper housing for all tools and implements as well as a storage for defective and broken parts.

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