Scammell.
Page 31
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F'DOUR of the familiar Scammell tractor-trailer vehicles are on view, one being of the frameless type designed for the transport of 3,300 gallons of fuel oil. By reason of the strength of the tank, with ribs riveted on, the necessity for a 'frame is overcome, so far as the trailer portion o the vehicle is concerned.
The four-cylinder engine is Mounted, together with the gearbox, in a: subframe, and the large differential hdusing is mounted to the rear of the gearbox, , supported by both the main and aubframes. The cross-shafts carry sprockets from which the drive is transmitted to the rear wheels of the motor section of the outfit. Twin solid tyres are, of course, employed on the driving wheels, also on the wheels of the trailer portion. Internal-expanding brakes operate on the central and rear wheels.
Suspension in all eases is by semielliptic springs, The construction of the turntable is interesting, and the arrangement by which the weight of the load is borne by the axle, but not by the frame of the motor unit, should be studied, separate springs being used for the two sections. Driven from the front end of the crankshaft is a three-cylinder radial air compressor by which the whole load of 12 tons can be discharged in a quarter of an hour.
Mounted on a trailer having, however. a channel-steel friune in this instance, is a 2,500-gallon tank wagon with elliptical tanks in five compartments. Only the trailer portion is shown.
Another interesting model is the 12ton vehicle with a dropped chassis frame, equipped with a winch and loading ramp to facilitate the handling of cable reels. The front wheels have pneumatic tyres.
Having a high-level frame is another Scammell for the transport of beer barrels. This is finished in dark blue and has stanchions and chains for the said transport of barrels. The driver's -cab is partially enelnsed and the driving chains are of the-twin roller type as opposed to single rollers on other maehines.
Originality in design is shown in the case Of the Autovan, which has a 24-ton load-carrying capacity, and is intended for short-distance hauls in suburban areas. The drive is taken to the front wheels from the three-cylinder radial engine; the crankshaft is mounted vertically, and the starting handle is situated on the top of the unit within easy reach of the driver. This is one of the most interesting exhibits in the Show.
In view of the novelty of this particular machine considerable attention may be devoted to it with advantage. Going
into _further details, w find that the bore is 4 ins, and the stroke approximately 4 5-16 ins., but, owing to the design of the engine and the fact that there is only one crankpin on the crankshaft, the stroke varies slightly in the different cylinders. Rated at 19.2 h.p., the engine should be capable-of dealing with the loads it is deatined.-te pull, particularly in view of the .faot. that the vehicle is intended for operation principally, in suburban areas. The cylinders are cast-iron, with aluminium heads, each of which is extended and webbed to form a cowl open at the top and end. Above the cowl is a six-bladed fan secured to the top of the crankshaft and rotating at the same speed. From this a blast of air passes between the cowls and the cylinders proper, providing each of the cylinders with a cooling draught over the effective area of 2 sq. ft.
Large bearing areas are employed and lubrieation is thoroughly carried out. It is interesting to note that the connecting rods are of stamped Duralumin, and a feature of the clutch design, unusual so far as commercial vehicles are concerned, is that Ferodo plugs are used in the single disc.
The gearbox is vertically mounted, and special provision has to be made for its lubrication in view of the position of the shafts. A double screw pump, resembling the familiar screw. of Archimedes, is Used, leading the oil through the layshaft to the constant-mesh gearwheel teeth, whence it drops over the rest of the rotating parts.
Scammell Lorries, Ltd., 14-18, Holborn, London, E.C.1.