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Show I TENDENCYTO USE TRUCKS OF I LARGER SIZES SPRINGS FROM I ECONOMY OF SINGLE HAULING HI '1 The tendency to usr motor trucks H of the larger sires is due to an eco- H nomic force that cannot b ignored H nor avoided. Experience has proved in every form of transportation that it H is cheaper to move freight in large H quantities than iu small lots. The factor of economy in highway! H J haulage is bound to have great force H in a period of lower prices and small H fr margins ot profit. State legislatures H and highway authorities seek to com- H bat this force in their efforts to pre- H vent rapid destruction of expensively- H built highways. The serious problem H ' ronfronting the country is to find H ' where the descending curve represent- H.':( ing decreased haulage costs crosses ; ihe ascending v representing in H '! j creased road maintenance. This is a H J matter of public economies, because ihe public pays the bill for transpor- H i tation as well as for highway work, fjjj No one appreciates the value of 1 I J good roads more than motor truck and ; 1 1 trailer manufacturers, dealers and j ( users. They know that bad roads de- 1 crease speed and increase operating !j expenses because of greater fuel con H j sumption, heavier repair charges and H 'i I more rapid depreciation of the vetai- llli dee. H Solution of the highway and traffic ',j problem lies in distribution of th- !j gros9 weight over moro wheels and a H i' longer wheel base. Concentration of n excessive weight on one wheel or one Ipt axle Is the cause of the greatest dc- H ; struction to roads. Contributing causes ;; are high speed, unsprung weight and : ; tractive effort, ijjl State legislatures have sought to H '; prevent concentration of excesglvt H 'j weight by limiting the load capacity fl j or the gross weight of vehicles Such H legislation makes It clear that the In- ' tent is to prevent concentration of !. weight This object is accomplished i when a given load is hauled on six or J j eight wheels instead of on four wheels, as when a Beml-traller or four-wheel trailer is used with a motor truck. Ten tons can be hauled on six or eight wheels With a single power unit more cheaply than on two power units. At the same time the grofs weight on any one axle or wheel and 'he weight per Inch of tire width are no greater than when five tons are hauled on four wheels. When present motor vehicle laws wero enacted legislators were not very familiar with the different types of trailers and tho ways in which they were used. This is partieularly true of the semi trailer and the pole trailer. These have but two wheels and the 1 1 .ml end of the trailer body or front end of the load rerts on and is sup 'ported by the rear end of the truck or tractor which draws tho trailer. The, combination forms a six-wheel outfit j that transports a single load. ' The four-wheel trailer, on the con-1 trary. carries its own independent load in addition to tne normal load carried on the truck. Together the truck and trailer form an eight wheel hauling outfit. ! The average distribution of gross! weight on a loaded four-wheel truck is 25 prr cent on the front wheels and 75 per cent on the rear wheels, conse-1 qaently the front wheels of a five-ton J truck carry a little more than 5000, I pounds and the rear wheels more than j I 15.000. The same gross weight on a six wheel semi-trailer combination, ! places about 8000 pounds on the front j wheels, 9000 on the drive wheels nndji a little more than 8000 on the trailer wheels. If the load Is divided between all four wheel truck and a four-wheel trailer, the weight distribution will bell I approximately 3000 pounds on the J I truck front wheels, 9000 on the drivel wheels, 4500 on the trailer front I i wheels and 4500 on the trailer rear I wheels. |