FAQ >> Moving the earth

Moving the earth

THE small boy with his pail and shovel and the tractor-bull- dozer combination have something in common-they both move earth. But where the boy works by handfuls, the dozer works in big yardages. And does this at a speed that often rivals a landslide. Road making, road-alinement work, canal construction, dam construction, paving and road surfacing, mining, terracing, channel deepening and tunneling are some of the projects on which the total amount of earth moved is beyond conception of the human mind.

The development of labor-saving equipment for gigantic earth movements, such as that at Grand Coulee dam, has been as remarkable as the tasks themselves. Because methods of a decade ago did not move earth fast enough, a contractor designed and built a scraper and other allied tools while working on big highways, railroad, dam and levee contracts. Then come the present fast-operating, big-capacity carryall type of scrapers, bulldozers, angle dozers, sheep-foot tampers, rippers and similar apparatus.

But these tools must be pulled, pushed or otherwise operated. The track-laying type of tractor usually does the pulling or pushing on tough jobs.

The precipitous Jack-Rabbit Trail in Riverside County, Calif., was done entirely with Diesel tractors, scrapers, bulldozers, rippers and tampers. In five months this equipment moved 650,000 cubic yards of earth. The total was something like 1,200,- 000 cubic yards. Only a few years ago cuts like this would have necessitated power shovels and much hauling equipment. The same fleet used on Jack-Rabbit Trail then moved on to work on a huge dam.

Precision is the chief characteristic of tractor and earth-moving machinery production. Unlike automobiles this equipment has no break-in period.- Tractors must be built to endure the relentless torture that goes with vast earth-removal projects. From the moment contractors put them on the job, tractors must pull or push and rip through gumbo, trees, hard- pan and rock.

The onlooker does not see the accurately balanced crankshaft of the huge Diesel; the oil seals for critical bearing protection to retain oil and keep out grit, dust and moisture; the phosphor-bronze bushings that guard against wear, nor the fuel injector parts held to an ac- curacy of two and onehalf millionth of an inch. Operators get a big pay load because the design of the bowl, set of the cutting edge and the front carrying apron speed the filling of the bowl through a minimum movement of dead dirt. The entire weight of the scraper can be thrown onto the cutting edge. Both the front apron and tail gate can be manipulated to facilitate the loading process.

The speed of the power control unit enables the operator to instantaneously raise the cutting blade when stumps or rocks are hit; thus the tractor need never be al- lowed to lug down to the point of inefficiency.

The front carrying apron forms a part of the scraper bottom; in other words the bowl fills from the middle both ways, to the back and onto the apron. The carryalls are mounted on big pneumatic tires and heavy- duty over-size roller bearings, consequently of great strength and resiliency, arc welded, reduce weight to a minimum, yet make for stout construction. As a result, the tractor pulling a carryall scraper wastes no power hauling the dead weight of heavy castings and bulky steels and so can ban- die-bigger pay loads.

A long wheel base, coupled wite instantaneous cable control, makes for fractional-inch accuracy in spreading with these carryalls- so accurate that blade graders usually can be dispensed with on finishing work.

The forepart of the load dumps automatically as the front apron, is raised, the remainder of the load is forced forward and out by the sliding tailgate-there is no chance for sticky material to re- main in the bowl.

And loading, hauling or spreading, the carryall is one-man operated-all operations sight and controlled from the tractor seat. When a road is to be made on a side hill that is too steep for a fold. The check valve automatically opens a line directly to the source of vacuum that is the great- est. When the motor is idling, this would be the intake manifold and when the motor is under load, it would be the vacuum pump. The combination 过the two sources of vacuum assures a aepenaaoie and constant supply of vacuum, which means that the windshield wiper will operate at an even Speed regardless of the load. The pump is easily installed without drilling by means of bracke inside of the pump re- quires no oiling, and the bearing is lubricated with a standard grease gun.

Almost exactly four years elapsed in the grinding and polishing of eighty-two inch telescope mirror recently completed for the new McDonald Observatory in Texa. The last stage was the application of a chromium and aluminum bath in a vacuum chmber. The three-ton reflector is made of Pyrex glass twelve inches thick.

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