Page:EB1911 - Volume 18.djvu/953

HEAVY] Gordon, A Treatise on Elementary Locomotion by Means of Steam Carriages on Common Roads (London, 1832, 1834 and 1836; Gore, Propulsion of Carriages on Common Roads by Power other than Animal Power (London, 1893); Graffigny, Manuel pratique du constructeur et du conducteur de cycles et d’automobiles (Paris, 1900); Grand Cartaret, Le Voiture de demain (Paris, 1898); Gray and others, The Motor Year Book (London, 1905 and 1906); Guerdon, Manuel pratique du conducteur d’automobiles (Paris, 1897); Gurney, Steam Carriages on Turnpike Roads (London, 1832); Hancock, Steam Carriages on Common Roads (London, 1838); Jenkins, Power Locomotion on the Highway (a guide to the literature; London, 1896); E. H. Knight, American Mechanical Dictionary, “Road Locomotives,” vol. iii. (New York, 1876); J. H. Knight, Notes on Motor Carriages (London, 1896); Lardner, The Steam Engine (7th ed., pp. 419–440; London, 1840); Lavergne, Manuel théorique et pratique de l’automobile sur route (Paris, 1900); Lavergne and Hasluck, The Automobile (London, 1902); Lieckfeld, Die Petroleum- und Benzinmotoren (Munich and Leipzig, 1894); Little, Automotor and Horseless Vehicle Journal (London, 1898); Lockert, Traité des véhicules automobiles (4 vols., Paris, 1896–1897); Petroleum Motor Cars (London, 1898); Maceroni, Facts concerning Elementary Locomotion (2nd ed., London, 1834); Powers and Qualities of Maceroni’s Steam Carriage Demonstrated (London, 1835); Steam Power on Roads, &c. (London, 1835); Mann, New Method of Propelling Locomotive Machines (compressed air) (London, 1830); Medhurst, A New System of Inland Conveyance for Goods and Passengers (compressed air) (London, 1827); Milandre and Bouquet, Traité de la construction, de la conduite et de l’entretien de voitures automobiles (4 vols., Paris, 1898–1899); O’Gorman, Motor Pocket Book (London, 1904); Perissé and Godfernaux, Traction mécanique sur rails et sur routes (Paris, 1900); Rose, A Record of Motor Racing (London, 1909); Salomons, The Horseless Carriage (London, 1895); Saunier, L’Automobile théorique et pratique (2 vols., Paris, 1899–1900); Sennett, Horseless Road Locomotion (London, 1900); Smith, History of English carriages and Motor Cars Tunbridge Wells, 1876); S.P.T.A. (Self-Propelled Traffic Association), Trials of Motor Vehicles for Heavy Traffic (Liverpool, 1898, 1899, and 1901); Sir H. Thompson, The Motor Car: its Nature, Use, Management (London, 1902); Wallis-Taylor, Motor Cars or Power Carriages for Common Roads (London, 1897); R. B. Whitman, Motor-car Principles (New York, 1909); Witz, Moteurs à gaz et a pétrole, vol. iii. (Paris, 1899); Yarrow, “On Steam Carriages,” ''Proc. Soc. of Eng. (London, 1863); Young, The'' Economy of Steam Power (London, 1860); Filson Young, The Complete Motorist (London, 1904); vol. xxxvi. (Head) “Steam Locomotion on Common Roads,” Proc. Inst. C.E. (London, 1873); Reports of Select Committees of the House of Commons (London, 1831, 1834, 1835, 1836, 1859, 1873, 1881).

Heavy types of motor-cars are now widely employed for commercial purposes. The earliest British-built type was the steam-propelled wagon, and its evolution was largely encouraged and hastened by important competitive trials, at Liverpool, in the years 1898, 1899 and 1901, which were conducted by the Self-Propelled Traffic Association. Other series of trials were held by the Royal Agricultural Society of England and the Royal Automobile Club.

From the end of 1896 to early in 1905 no commercial motor vehicle was legal in England if its unladen weight exceeded 3 tons, and this limitation caused much financial loss to purchasers who overloaded them. The Heavy Motor Car Order of 1904, which came into force on the 1st of March 1905, increased the maximum unladen weight to 5 tons, whilst limiting the gross weight to 12 tons; by the same order, the combined unladen weight of a motor wagon and the single trailer which it is allowed to draw was fixed at 6 tons. In effect, the gross weight of a trailer and its load may not exceed 8 tons, thus yielding a total gross weight, for loaded wagon and loaded trailer, of 20 tons. Excesses in any particular cause a commercial motor to be treated as a “heavy locomotive,” or traction engine, when its freedom of movement, speed, &c., are restricted more severely.

Miniature traction engines, constructed to comply with the requirements of the Motor Car Acts and Orders, have progressed since 1905; they are chiefly used where it is a convenience to separate the power and carrying units, as by furniture-removal and other contractors.

The working cost of a steam wagon with a 5-ton load, in Great Britain, inclusive of provision for interest on capital, depreciation and maintenance, varies from 7d. to 9d. per mile

run, on an average basis of 180 m. a week; with a trailer carrying another 3 tons the corresponding figures vary from 9d. to 1s. per mile run, according to nature of roads, gradients and fuel available. The inclusive working cost of a tractor, on macadamized roads, is generally about 15% less than for a 5-ton wagon, but a standard tractor cannot haul more than a gross load of 8 tons behind the drawbar—except on dry and level roads. On granite setts the extra vibration often causes undue wear and tear, unless the suspension of the tractor be very good.

Vehicles in which the power is derived from internal-combustion engines are commonly known as “petrol” vehicles. Petroleum spirit of 0·700 specific gravity is usually the fuel, but many are now supplied with spirit of 0·760 specific gravity; the range of boiling points is the criterion of satisfactory use—not the density. Petrol vehicles are, practically, stoutly-built motor-cars, and some of the models now in use have been developed from accepted designs of lighter types. There are, however, numerous manufacturers who construct solely for utility purposes. Below net loads of 2 tons, the petrol-propelled vehicle has a virtual monopoly of use in England; above that, it shares the trade with steam. A tabular statement of current working costs of approved petrol vehicles is published herewith.

Before proceeding to describe and illustrate representative types of vehicles, tractors and special machines, a brief summary of the outstanding points in the English statutes and orders which apply to heavy motor-cars may well be given. Any motor-car with an unladen weight in excess of 2 tons is held to be a “heavy motor-car,” and a “trailer” means a vehicle drawn by a heavy motor-car. The expression “axle weight” means the aggregate weight transmitted to the surface of the road or other base whereon the heavy motor-car or the trailer moves or rests by the several wheels attached to that axle when the heavy motor-car or trailer is loaded. The expression “weight,” in relation to a heavy motor-car or trailer when unladen, means the weight exclusive of the weight of any water, fuel or accumulators used for the purpose of propulsion. All heavy motor-cars have to be registered with a county council, county borough, or other registering authority, and owners have to declare, on suitable forms, the unladen weight, the axle weight of each axle, and the diameter of each wheel. When a registration certificate is issued it bears these data, in addition to a statement of the width and the material of the tyre on each wheel, and the highest rate of speed at which the heavy motor-car may be driven. The owner, after registration, must cause to be painted, or otherwise plainly marked, upon some conspicuous part of the offside of the heavy motor-car, the registered weight unladen, and the registered axle weight of each axle, whilst, upon the near side of the heavy motor-car, he must similarly cause to be painted the highest rate of speed at which it may travel. Width of tires, which in no case may be less than 5 in., varies in relation to imposed load and wheel diameter, and a table of these is issued by the local government board. It is specified that “the width shall not be less than that