Yet Another New Napier.
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First-published Particulars of a 2-ton Model, in the Design of which many cf London's Motorbus Lessons have been Incorporated.
A fortnight ago we were able to afford our readers an indication of the forward policy of D. Napier and Son, Ltd., in regard to its business-vehicle policy. We then described and illustrated at sonic length the company's latest 30-cwt. model. We promised on that occasion, within the next few issues, similarly to deal with the company's even more interesting 2-ton design. We now propose to redeem that promise, in spite of exceptional pressure upon our space which is incidental to our advance treatment of the Manchester Show, and to the many requests we are receiving for manufacturers to give first publicity to quite a crop of new models.
Based on Recent Experience.
This latest Napier, as will be seen from our fullchassis photograph which is reproduced below, is entirely unlike previous models for which the famous Acton factory has been responsible. As we suggest in our sub-heading to this article, the Napier management has decided to offer to users a chassis, of medium-load capacity, with a considerable portion of its design based on recent motorbus experience. Provided that any such adaptation be most carefully considered in the light of the very-specific nature of motorbus service, no finer lessons can he applied. Our personal examination of the first of the new
Napier two-tonners impresses us with the fact that its designer has made no slavish copy of the B-type, although he has obviously been influenced by it. Had a e been asked to classify this new machine, we should have called it a 2-tonner at least, but the Napier authorities are perhaps well advised to offer it for the carriage of net loads of 40-cwt.—no doubt with full knowledge of the fact that most users overload to an appreciable extent. We only trust that it will be allowed to remain a 2-tonner—with an inviolate reputation for regularity and that it will not eventually be dubbed—as seems the indeterminate fashion nowadays, a 40-50 cwt. chassis.
A Chassis of Bold Outline.
There are many details of design which deserve particular mention, and we will indicate some of these at a later stage. Briefly, we may describe this new chassis as having a four-cylinder 30 h.p. engine, a single-disc clutch, a four-speed gearbox and a worm-driven live axle. Cast-steel road wheels and a tubular radiator with cast headers, the latter of somewhat monumental outline, we may say, help to impress one with its family resemblance to the Btype and other machines of the same "breed."
The engine has a. relatively long stroke for an industrial model--5 in. to a bore of 4 in. Napier engine construction has been adhered to in the main ; the well-known and equally well-tried twin-jet carburetter is employed. The lubrication system appears to be all that. could be desired in regard to thoroughness ; an oil pump, operating in a sump, delivers to the drilled crankshaft; troughs are not employed. A special overflow and drain arrangement is a useful fitting.
A Good Clutch.
Imongst our useful selection of detail photographs, it will be found that we have reproduced one of the clutch. This component is frankly a copy --and we consider an improvement in regard to its arrangement—of the much-tested De Dion singleplate clutch, with the important improvement of a fabric, face for the original steel disc. Multiple leather rings are again in this model employed for universal-joint purposen. Similar devices, concerning the longevity of which there has been much discussion, are being employed, we are told satisfactorily, in London motorbus service.
The gearbox is characterized by its simplicity. Generously-proportioned spur gears on short stiff shafts, which latter are mounted on annular roller bearings, provide for three reduction ratios, and one, the top, direct drive ; in addition there is, of course, a reverse train.
A Sturdy-looking Axle.
Another leather-coupled shaft drives to the wormdriven back axle. The particular aim of the designer appears to have been to embody the maximum of accessibility in this important component. A massive pot casting, with hollow-forged flanged sleeves, assumes all stresses arising elsewhere than from the power transmission for which the propor tions of the differential shafts are ample. The lowest of our group of detail illustrations reveals the manner in which it is possible to lift the worm, its casing and the complete differential grouping, without taking down the axles proper, and without even jacking up one of the wheels. These last run on floating bushes of chilled phosphor-bronze, the journals themselves being sheathed with separate hardened-steel sleeves. A pressed-steel torque .bar controls the twisting effect on the axle, its front end being spring-mounted in a pivoted housing that is located close to the rear of the gearbox.
Two sets of brakes are installed, one, which is pedal operated, at the back of the gearbox, the other, controlled by a pull-up hand lever, on the hind-wheel drums. Special care has been taken with the arrangement of the engine control, a simple throttle, regulated by a small pedal, being all that is within reach of the driver for this purpose.