The larger the equipment for a specific job in the earth-moving field, the more quickly and efficiently that job can be done.
Unfortunately, the very size and weight of many present units means that the transportation of them involves a ponderous task. If increased capacity could be obtained with no increase in gross vehicle weight, and with only negligible differences in dimensions, major progress could be made in the equipment field.
Even if physical dimensions involved no problem, the weight and placement of such essentials as tires, wheels, brakes, drive chains and engines, all tend to limit the payload capacity of a given vehicle.
Through the judicious use of aluminum alloys in proved applications, a 10 to 15 per cent increase in payload capacity can readily be achieved at no increase in gross vehicle weight. The aluminum applications referred to have been proved both in over-the-road and in off-highway service.
Aluminum equipment has and is being used on highway and general purpose construction work to move sand, cinders, salt, gravel, bulk cement and earth and rock fill. The weight savings over steel - depending on the size of the unit - varies from 1,500 to 2,500 pounds for dump bodies mounted on a straight truck. On dump trailers, 2,300 to 3,200 pounds of weight can be saved.
As a rule, aluminum will provide a 50 per cent saving in weight over the steel unit it replaces. Only a modest increase in the height of body sides or in the length of a body is required to handle the increased payload.
In off-highway hauls, benefits from using aluminum have been even more spectacular. The weight saving gives the operator 10 to 15 per cent greater payload for the same gross vehicle weight. This means an extra profit yield to the operator of 1-1/2 to 4 cents per cubic yard of material hauled.
Should a fixed number of cubic yards be required in a prescribed time, as in most mining operations, the number of trucks required for the job could be cut 10 per cent. In short, nine trucks equipped with aluminum bodies would do the work ordinarily calling for ten trucks.
Computing ownership and operating costs at approximately $12.50 per hour per truck, the savings in eliminating one truck would amount to $100 in an 8-hour day. On a yearly round-the-clock operation, savings at this rate could exceed $100,000.
Aluminum units have been built and operated to prove the economies claimed. The largest is a 69-cubic-yard bottom dump (more) coal hauler. The use of aluminum in this unit saved 10,000 pounds (5 tons) of weight. This hauler and others like it have been in steady operation since 1953.
Another, a 28-ton capacity rock body has been in operation since September, 1956. The weight savings in this unit was 7,000 pounds. It has operated 600 hours, and has needed no more servicing than would have been required of steel bodies under the same, rigorous conditions. There has been no major difficulty.
Many additional applications of aluminum are being considered for earthmoving equipment, and many are now under test. Experience with both commercial and experimental applications is mounting rapidly. The aluminum alloys and welding techniques have been proved and are available. Further consideration by the design engineer is hastening the day when the use of aluminum in earth-moving equipment will be general, affording increased efficiency to both operator and builder alike.