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Reviewing the present transportation problem in regard to its demand for larger motor-vehicle units of transport, the author says that the motor truck is proving to be successful in the movement of practically all local freight and that the motorcoach is meeting with greater and greater favor as the logical vehicle with which to meet the demands of the traveling public for better transportation facilities. Although the present types of motor vehicle are serving present needs in a more or less successful manner, when strict economics becomes the standard for measuring road transportation a demand will be made for vehicles that will accommodate the maximum freight or passenger loads in the minimum of street space. At speeds governed within limits of safety they will offer the utmost comfort for passengers and will haul perishable goods over long distances in quantities large enough to assure strictly economic operation.

Substantial reduction of motorbus depreciation by materially increasing the useful life of the vehicle is an important problem now facing the automotive engineer. The author contrasts present motorbus life with that of street-cars; he finds a probable life of 4 or 5 years only for the former and 20 to 25 years for the average type of trolley-car. This, in the case of the motorbus, he says, is too short a period of usefulness and directly affects operating costs, since the increased cost of motorbus maintenance offsets its lower initial-cost. Demand for maximum comfort, safety and speed from the public and for economical operation from the operators has renewed interest in the six-wheel motorbus and given its design an impetus, although present four-wheel motorbuses of 25 to 30-passenger capacity have, and will continue to have, a very definite field and will not become obsolete due to replacement by other types.

The purpose of the tests described was to subject various models of truck to shocks far in excess of anything likely to be encountered in actual service, to study the effect of different spring and tire equipment on impact and the effect of unsprung weight upon road impact, as well as the effect of varying speed on these impacts. A series of “jumping tests” for motor trucks was conducted and a new system of motion pictures, capable of being afterward slowed down for analysis, was used to record the results. Trucks were run at speeds of from 15 to 18 m.p.h. along a straightaway course and over a sharp incline. The trucks sprang into the air and struck the ground as from a vertical drop of several feet. The apparatus and the five trucks used are described fully, the data obtained and the method of computing results are presented, and the analysis and conclusions which follow are sufficiently detailed to afford much constructive information on this subject.