THE N.A.G. LORRY.
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Post-war German Lorries now in this Country.
BEFORE AND DURINGthe war, probably one of the most outstanding features in the construction of German mechanical products was thoroughness.; so much so in fact that the words "Teutonic thoroughness" came commonly to be used in our language, when criticising any production or -manufacturing method in which more than the average amount of care was displayed. TS no lees extent does this now apply in post-war days, and the new N.A.G. lorries now in this country, and recently inspected by The Commercial Motor, are still noteworthy for this quality, although it is apparent from even a cursory examination that many lessons in various, directions have been learnt as a result of war service. This applies more particularly to the capabilities of the lorries, since the present models are designed to do as was required of them on active service, viz., to pull -big loads, and to "get there," but not necessarily at a high speed. Two types, similar in design, are being made, and examples of both have been imported by Thos. A. Rowley, Ltd., 83, Colmore Row, Birmingham, who are sole concessionnaires for them in Great Britain and Ireland. One is a lorry of three tons capacity, supplied with chain or cardan drive and for use either with or without trailer, and the other has a capacity of four to five tons, with chain drive, and can also be used with a trailer if so specified. On the 'basis that the fewer parts that are made by one concern the better will they be made, the N.A.G. Co. has specialized in one size of engine only, and the same motor is, therefore, fitted to both lorries. It has four cylinders, each with a bore and stroke of 130 mm. and 160 mm. respectively., and, at 900 r.p.m., develops about 45 h.p. All valves are mechanically-operated, and are interchangeable, the cylinders being T-headed and having the inlet valves on the one side and the exhaust valves on the other.
The crankshaft is housed in three main hearings, and, since inlet and exhaust valves are on opposite sides, it follows that there are two camshafts, one on each side of the crankcase, which is split across the centre line of the main bearings. The bottom half of the crankcase serves as an oil sump, and also carries the brackets for the main bearings. It would appear from the construction of the engine that the manufacturers do not anticipate having any trouble with the bearings, since no inspection traps are provided. Moreover, in eider to obtain access to the big-ends, it is necessary to remove the complete engine from the frame, as the bearer brackets are cast on the bottom half of the crankcase.
The lubrication system is automatic,
and depends upon the driver forno further attention than the filling up with oil, the lubricant being circulated by means of a. gear pump driven off one of the camshafts through pipes to the main bearings. A trial cock is fitted, Which enables the driver to satisfy himself that the pump is functioning correctly. The Pallas carburetter, with a hot-air muff, is employed, and it is claimed that petrol, benzoic, alcohol, or any mixteres of these fuels can be used with extreme economy. The hot-air muff, which should be very • effective in practice, is quite simple in form, and consists of a metal sleeve round the exhaust pipe, having holes in either end, through which air is drawn and passed across the surface of the exhaust Manifold, and thence to the carburetter through an intake pipe connecting the two.
Ignition is assured by a Bosch magneto, which automatically varies the point of ignition, and, inctependently of the driver, fixes this paint according to the number of engine' revrolutions per minute. *Reverting to the question of carburation, it should be stated that, in order to prevent the over-running of the engine either under load or when running light, a throttle governor is fitted, which limits the speed to a maximum of about 10 m.p.h. The cooling water is circulated by a rotary pump, and passes through a massive radiator carried in the conventional position, behind which is a large three-bladed fan running at slow speed off the _half-time shaft. The N.A,G. designers are, evidently, amongst those who do not think that water itself is a sufficient lubricant for rotary pumps, since they have provided a large grease cup to the pump spindle.
The question of .efficient cooling seems considerably to have exercised the minds of the designers, since, in addition to the water pump, the large radiator, and the three-bladed fan ; the flywheel and the clutch arms are also vaned in fan form. A commendable point in connection with the cooling system is the extreme accessibility, of all the water pipes and joints; in fact, it may be said
that accessibility is quite a feature of the whole design. 'This, perhaps, is not sur
prising, since it is one of the points which was insisted upon in the German war subsidy specification, which is closely followed in the N,A.O. lorry. In order, as far as possible, to eliminatetthe ill effects of.vibration and the risk of misalignment of the transmission, through distortion oft the chassis frame when traversing rough roads, the complete power unit is mounted in a frame on flat mild steel .straps between the crankcase bearers end, frame members, a method ef assembly which, whilst being perfectly rigid under ordinary conditions, provides a certain amount of spring in the attach. merit.
The drive is ,taken through a cone clutch to a four-speedand-reverse gearbox. In this clutch the male member is a steel pressing, whilst the fabric lining is carried on the inside of the flywheel. The gearshafts run in ball bearings and the gearwheels are made of chrome nickel steel, whilst the control lever operates through a gate, mounted on the right side frame member and conveniently situated to the driver's right bald. In the case of the ehain-drive models, the transmission rearwards from the gearbox is by an openS propeller shaft to a differential shaft near the rear wheels, and thence by chain from a large sprocket on each end of this shaft. The drive to the cross shaft is through bevels; this type ofigearing is also employed in the case of the three ton live-axe' type. The differential housing is anchored to a ll-section cross member of the frame, which member is, in turn, strengthened by the 'useof two tubular piekes which connect and brace the two branches of the U. The brakes arooperated by the usual 'perlahand side lever, and consist, in the former case, of a,contracting, band on a, large,drum iminediately at the rear of the gearbox, and,lin thedatterkcase, of internal expanding shoe. brakes at each rear wheel. 'The foot brake may be water-cooled on long descents from a tank mounted on the dash,land the hand brakes are compensated to give an equal
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pull from the one lever. The steering gear is of the worm-and-sector type. The main fuel Leek is situated under the driver's seat, and fuel is supplied to
the carburetter by gravity: Provision is made, however, for fueling the petrel -under pressure should' the natual piesmire be instificient, as in .the case of climbing a steep gradient.There is also an additional tank mounted on the driver's side of the dash, which may be used simply for a source of fuel supply when starting up. That is to say; if the engine normally is. running on a poor quality of fuel a small supply of better.
class spirit to facilitate starting can be carried in this small tank.
There are many mieor points in con. nection with the design of the N.A.G. chassis, which, by reason of the obvious attention that has been paid to details, justify our opening paragraph on "Teutonic thoroughness." For instance, provision is made for lubricating the moving ends of the radine.rods without giving the driver the necessity of crawling on his hands and knees with . an oilcan... In an easily accessible position, near the forward end of each radius rod, is mounted .large oil cup, from which the lubricant is conducted to the axle bush by means of a pipe. In the end of each shackle pin is a threaded plug, and a grease gun is provided, which screws into the thread exposed by removing this plug. end, consequently, permits of simple lubrication for the spring shackle pin. Incidentally, -the shaelles arc bridged with a middle -web, which should materially decrease the possibility of the development of weakness at this part.
The N.A.G. catalogue illustrates a variety of types of body, but the particular ones fitted .tc the chassis at present in this conntry are of the open lorry type with drop sides and four hoops, over which a canvas cloth can be fastened if desired. The driver's cab is quite an elaborate affair, and provides absolute protection from the elements.
As regards the mechanical features of these vehicles, there is apparent through out the design a tendency to consider utility before appearance. That is to say, although the design of the details cannot be termed crude, it is evident that the designers have net placed the same importance upon or made the same efforts to obtain an artistic appearance, as many engineers have done in this country. In this respect the design of these vehicles is partictisatly worthy of study by heavy veluele manufacturers. It is ;wily very questionable whether the commarcial-verecle buying public really appreciates ultr.secleanainess in ‘design, and places as much importance, as many people appear to imagine, on the outward "looks of mechanical details. Nevertheless, some heavy vehicle constructors are very obviously influenced by the tendencies in touring car design, and it would seem that German engineers are not influenced by ititinothe same way.
In 'general principles, the three and four tremors are very similar, and only
• differ as regards their load capacities, and in. one or two mechanical details. Suspension is the same on both types, namely, semi-elliptic all round • the rims are the. same size, and are Siod, after arrival over here, with 1,030 mm. by 140 min Avon solid rubber tyres.