Two New Commer Light-lorry Chassis
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TO be added to the list of new commercial vehicles that can now be
purchased by civilian • operators engaged on work of national importance and able to produce the requisite Ministry of War Transport licences to acquire are two new Commer models, having pay-load ratings of 15-cwt....and 25-cwt. respectively.
They are Superpoise forward-control four-cylinder chassis, and are based on the design of the similar machines with semi-forward control that were introducedat the beginning of this year. Both the latest models have almost identical specification's, bat outstanding differences are in the tyre equipment and the axle ratios.
Whilst the 15-cwt,' chassis is shod avith 6-18 tyres on all wheels, the 25cwt. machine has 6-20 tyres at the front and 32 by 6 truck tyres at the rear. This affects the chassis weight, the figures being 201 cwt. and 212 cwt. respectively. As for the maximum permissible gross weight, 50 cwt. is quoted for the 15-cwt. model and 6:3. cwt. for the 25-cwt. machine. Regarding the gear differences, the respective ratios-are 6 and 7 to 1; we, give the intermediate gears later.
The following facts relating to the general specification' are common to both models. With a piston displacement of 1.944 . litres (75 mm. by 110 rum.) the engine is rated at 13.95 h.p. and develops 40 b.h.p., the maximum torque exerted being 79 lb.-ft. Cylinder block and crankcase form a compact nickel-chrome-iron casting, the detachable head incorporating high-efficiency combustion chambers. Of silicon-chrome steel, the valves work in renewable guides, whilst the tappets are operated by a hardened and ground three-bearing camshaft. There are dual valve springs and the exhaust valves seat on replaceable hardened iron inserts.
Light cast-iron pistons with 24-mm. gudgeon pins and I-section connecting, rods impart power to "a sturdy crankshaft which is statically and dynamically balanced and V runs in three
58-ram. white-metal, steel-backed bearings. Driving the camshaft is a duplex roller chain, whilst distributor and oil-pump are operated through a skew gear. • A large-section belt runs the fan, water pump and dynamo.
• Incorporated in the lubrication system are two filters, and there is an efficient crankcase ventilating system. From a 10-gallon tank an A.C. pump feeds,petrol to a Solex "self-starting" up-draught carburetter, mixture entering the cylinders "via a hot-spot manifold. Wide-gap 14-mm. sparking plugs are standardized, and the ignition system also includes a Lucas c2i1 and automatically controlled distributor. A .thermostat is incorporated in the engine-cooling, systern. Among other items • of electrical equipment. may be named Lucas 12-volt, ventilated dynamo, starter of the ,same make and 63 am.-hr. battery.
, Behind the flywheel is a 9-in, singledry-plate clutch, which conveys the drive to a four-speed gearbox. The complete power unit is mounted at three points on rubber-cushioned supports.
Connecting the gearbox with the bevel-drive axle is a Hardy-Spicer shaft incorporating needle-roller universal joints. , .
Adequate strefigth, in the case of the 15-cwt. model, and ample strength M that of the lower-rated machine, is afforded byframe side members measuring 5 ins. by 21 ins. by 5-32-in. These are well braced and the whole constitutes a robust structure. Measuring 47 ins, long and built up of 21-in.
plates, the rear springs are of silico-manganese steel and are fitted with renewable bushes. Except for the dimensions, which are 36 ins. by 2 ins., the front springs are similar.
To ensure rapid retardation, brakes are employed affording a total frictional area of 193 sq. ins.; they are Bendix products. Both the front and rear pairs of drums are Millenite castings, the respective dimensions being 11 ins. by 1/. ins.
and 14 ins. by 2 ins. ,5? Here are some of the principal chassis dimensions: Wheelbase, 10 ft.; overall length,' 15 ft. 3i ins. (the larger model is 15 ft. 41 ins.); width, 6 ft.; body space, 11 ft. 161 ins.; and frame heights, laden, (15 cwt. ) , 2 ft 0/ in. and (25 cwt.), 2 ft. 2/ ins. Overall gear ratios are (15 cwt.), • 28.7, 17.3, 9.96 and 6 to 1 and (25 cwt.), 33.5, 21.8, 11.62 and 7 to I.
Generally speaking, the new chassis is designed and built on workmanlike, straightforward lines, and, like its. fellows, should enjoy the popularity that , Commer products have earned.
Good appearance is a pronounced characteristic, and the advantages of the Superpoise design are unquestioned. Furthermore, the big body space in relation to moderate wheelbase permitted by forward control is a definite attraction.