AN AMERICAN CHASSIS FOR 30-cwt. LOADS.
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Details of the 30-cwt. Mason Chassis, Built for High-speed Work and Marketed in this Country by Durant Motors, Ltd.
OW THAT the lighter types of chassis for commercial use have practically reached the limit so far asreliability n service is -concerned,increasing attention is being turned to the possibility, of developing models which are capable of :attaining eoesiderablY-highersspeeda than those at present sinployedsin obitnesircial: work. Such Chassisrequire greater engine power; higher gear ratios and 'more powerful brakes, combined with comparatively light weight,and at the mane •
time 'their 'upkeep niust ,not be. exceSSively costly,'otherwise, the advantage of high speed may easily be more than counterbalanced.
It is very difficult to meet all these requirements in the one .Vehicle. What, however, appears to be a successful effort to do se has resulted in a new 30-cwt. model of American origin, which is being sponsored in this country by Durant Motors,. W., Trading Estate, Sleigh, Bucks. _We have not yet had en opportunity of testing this vehicle, but it is stated that it has all the strength necessary for heavy haulage on rough roads, end at the same time has ample speed capabilities which should satisfy the most exacting user.
. On top gear the ratio is 4.9 to 1, and the vehicle, which is known as the Mason Road King, • can be operated with full load at speeds in excess of 40 m.p.h., although, of course, such speeds would certainly not be countenanced in areas where there is any considerable amount of traffics J124 To provide the necessary power, the four-cylinder engine with which.the vehicle is equipped has "shore and ;stroke of • 4 ins. and 5 ins. respectively, developing from 35 h.p. to 40 h.p. The crankshaft runs in Timken taper roller bearings. .These bearings, which are a size larger than those generally found in the majority of other American vehicles, are also used for the front and rear axles.
Carburation is attended to by a Johnson instrument of the automatic types and ignition by an Auto-Lite sets Incidentally, the equipment includes electric starting and lighting and an electric warning horn.
The cooling water is circulatedthrough the cylinder jackets , and the extra large radiator by a centrifugal pump. The clutch, which is of 10 ins, diameter, is a Hoosier multiple disc. It can be removed witheut disturbing the engine or transmission, the only part which has to be disconnected being the universal clutch between the clutch and gearbox.
The last-named is of the sliding selective type giving three Speeds in a forward direction and the u,sual reverse. Two universal joints are used on the propeller shafts and the final drive is by spiral bevel gears contained in an axle of the full-floating type, provided with a torque member.
The front axle is an extra heavy drop-forged type with integral forks, and the connecting link between the steering arms is behind the axle. The brakes consist of external-contracting bands operated by foot, and internal-expanding shoes operated by a hand lever and which is treated as the emergency brake. Both these brakes have shoes 3 ins, wide, thus giving ample braking area, which is so essential in a vehicle capable of attaining high speeds.
Irreversible steering is employed, as it is particularly importa,nt :that shock on the wheels should not be transmitted through the steering gear and perhaps cause swerving. Artillery type wheels are utilized, and these are fitted with heavy-duty one-piece demountable rims equipped with Firestone cord pneumatic tyres, 34 ins. by 5 ins., all round. .
The wheelbase is 14 ft. 5 ins., the overall width 5 ft. 6 ins., the loading space from the dash to the end of the frame is 10 ft. 10 ins., and. the width of frame 2 ft. 6 ins. The weight of the chassis with bonnet and mudguards is 2,950 lb., and the equipment, apart from that already mentioned, includes a storage battery, speedometer, ammeter and complete .set of tools.
Special attention has been paid to the question of obtaining a low platform to enable the vehicle to hold the road well.
The springing is also good, the rear springs being 3% ins. long and 2ins, wide, and the front springs 284 ins., long.
The price of this new chassis is £380. In the opinion crf the makers of this new chassis the value of a commercial vehicle to the user is dependent upon three things: (1) The degree of economy with which it can he operated; (2) the ease with which it can be kept in satisfactory mechanical condition without losing time on service; (3) the range of uses which it will meet, satisfactorily.
The average commercial vehicle is, in their opinion, built to meet one only of these three requirements. It is either designed for heavy haulage at slow speeds or for rapid delivery work. In the former case speed is sacrificed, for surplus weight, which increases the operating costs and limits its utility ; in the latter case stability and strength are sacrificed for speed, and it is the claim of the builders of this new model that it meets all,three of these important needs, having the strength necessary for the heaviest work within its load-carrying capacity, a maximum speed which is ample for all purposes, and its units are so built that repairs can be made or replacements carried out with a minimum of time lost.
Whether these claims are justified remains to be seen when examples of the chassis have been in active service for a. sufficiently long period in this country.