Class II — The "Insulated Unit" Type.
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The only example of this interesting class, which had materialised at the recent Olympia Show, was the muchdiscussed Austin, for which the Austin Motor Co., Ltd., of Longbridge Works, Northfield, near Birmingham, is responsible. The amount of careful thought expended on this design, compares very favourably indeed with any .other model so far produced exclusively for cab or light-van %veld:, The E igine, clutch, and gearbox are all mounted on the subsidiari frame, which itself is suspended at three points through rubber buffers, from the main chassis frame. It will be at once seen, therefore, that the more delicate portions of the mechanism are completely insulated from road shocks, the while they are rigidly connected by the stiff little underframe. This compact •arrangement is quite original, and promises excellent results. To secure a short wheel base and maximum lock, without undue width of track, the arrangem.ent of the engine—centrally under the driver—is eminently suitable. The steering gear is arranged centrally, and the position of the driver in the middle of the chassis enables him to obtain a clear view behind on both the near and off Fide of the vehicle, which is, of course, impassible on the more usual type of cab. By the provision of folding shelves, the driver can carry luggage on both sides of this machine.
The engine is even . more accessible than on the ordinary bonneted chassis, as there are no mudwings to mask the engine. Large, detachable, side panels, and a forward-hinging driver's seat, render it possible to get at every portion of the engine without the slightest
inconvenience. The whole design is
full of interesting and cleverly:thoughtout details, but we only have space to mention the non-jointed gearbox, and the beautifully-constructed, live, back axle. We have already fully described this machine in our isside of the 26th March last.
Class III—The "Separate Unit" Type.
Under this heading, the vehicles manufactured by most makers and agents fall. They include : The New Arrol-Johnston Car Company, Limited, of Princes Street, Regent Street, W.; Belsize Motors,Limited, of Manchester ; Berna Motors, Limited, of 3, Lombard Street, E.C. ; S. F. Edge, Limited, of
14, New Burlington Street, W.; Humber, Limited, of Coventry; J. A. Lawton and Company, Limited, of 35, Hardman Street, Liverpool; Mann and Overtons, Limited, of 7a, Lower Belgrave Street, S.W.; Stephen A.
Marples, of 335, High Holborn, W.C. ; Renault Freres, Limited, of rg, Newman Street, W.; The Star Engineering Company, Limited, of Frederick Street, Wolverhampton ; Sidney Straker and Squire, Limited, of Nelson Square, BIackfriars, S.E. ; and The Wolseley Tool and Motor Car Company, Limited, of York Street, Westminster, S.W.
The type of motorcab chassis made or sold by each of the above concerns consists, as shown in our third diagram.of a two-cylinder or a four-cylinder engine (Al, which transmits its power through a clutch (B) to a gearbox (C), and thence, through a propeller shaft, to the differential gear and live axle (E). TwO of these companies, viz., Mann and Overtons and the Woiseley Company, supply cabs having either two or four cylinders. On the engines of all makes, the valves are mechanically operated, and the ignition, in all cases except on the Arrol-Johnston, the Humber and the Star vehicles, is by hightension magneto. The Arrol-Johnston has a low-tension magneto, and the Humber and Star cabs are fitted-with a coil and accumulator. The cooling of all these engines is effected by means of a radiator of the gilled-tube or the honeycomb type, and, with three exceptions, the circulation of the water is maintained by means of a geared pump. The three exceptions are the Marples, the Renault and the Straker-Squire, in each of which types the thermo-syphon system of circulation of the water. is relied upon to effectively cool the cylinders. The leather-faced, cone-type clutch appears to be the one in most general use on this class of chassis, and the threespeed-and-reverse gearbox, with sliding gears, appears to be equally in favour; the only exception to this type is the Arrol-Johnston which is provided with four forward speeds, and the clutch on this machine is of the HeleShaw type.
The neatness of the arrangement of the gearbox on some of the makes which we mention under this class is worthy of special mention. Amongst these we should include the Berna, in which the shafts are extremely short; this particular gearbox is a good example of careful and economical design. The final drive, from the gearbox to the road wheels, Th all but one of the vehicles in this class, is taken through bevel gearing. The one vehicle which differs in this respect is the Napier, handled by S. F. Edge, Limited, and on this cab, with a view to securing an extremely silent vehicle, worm gearing has been adopted. The Arrol-Johnston cab is fitted with that company's horizontal engine, which has four pistons working in two cylinders; by an ingenious arrangement of -connecting rods and rocking_levers, each_pair,of pistons work on to one crankpin of a doublethrow crankshaft.
Class 1V—The "GearDriven, Fixed-Axle" Type.
There are only two makes of vehicles included under this heading, and these are : the toh.p., two-cylinder cab by De Dion-Bouton,Limited,of io, Great Marlborough Street, W., and the two vehicles by A. Darracq and Company (19o5), Limited, of Walnut Tree Walk, Kennington, S. E. Strictly speaking, the De Dion cab should be included under the third class (that of separate units), as it is undoubtedly the finest example of that type. In this particular vehicle, accessibility of all the parts, and the independent-unit system of design, has been carried to such an extent as to make it an extremely cheap vehicle to maintain. As, however, the differential gearing is combined in the . same casing as that of the change-speed gearing, we are obliged to place it in the same class as the two Darracq vehicles.
The diagram for Class IV shows the disposition of the parts in this class of chassis. Up to, and including the disposition of the clutch, the chassis does not differ from those described under Class III, but, from the clutch, the drive is transmitted, through a long propeller shaft, to the change-speed and differential gear, and, from the differential gear, by means of two short shafts, direct to the road wheels. These two makes differ from each other in one essential feature : The gearbox in the De Dion vehicle is suspended from the main frame, and the two short shafts from the differential gear (which are provided with universal joints) take account of all the spring deflection, whilst, on the Darracq vehicles, the gearbox is mounted on a live axle, and it is arranged in such a way that the centres of the differential-gear shafts coincide with the centres of the two road wheels. The two shafts, therefore, in the hitter case, need not necessarily give universal motion. The two Darracq vehicles, like most of those included under Class III, are fitted with leather-faced cone clutches, but the De Dion cab chassis has a plate clutch, and this vehicle's engine is fitted with the well-known De Dion type of dual ignition, which employs that maker's special high-tension magneto and coil.
Adams.
The Adams Manufacturing Co., Ltd., of Bedford, has secured a considerable reputation for its distinctive, " pedalsto-push " machine, amongst users of moderate-powered pleasure ears. Many of our readers will remember that it was the Adams car which, not long ago, secured a first prize for appearance at Ranelagh, and a silver medal for ease of manceuvring in the Town Carriage Competition of the Royal Automobile Club.
This company is now producing a motorcab of which the chassis is practically identical with the machine that secured such gratifying results in the town-carriage branch of the pleasurevehicle trade. Either a two-cylinder or a four-cylinder engine is fitted, as desired. The standard ignition is hightension magneto, and the cooling equipment is of the thermo-syphon description. The change-speed gear is of the company's patent, enclosed, epicyclic type, and furnishes three speeds forward, and a reverse, all pedal-operated.
The interesting vehicle which weillustrate—by means of a general ar-rang .ment drawing—at the foot of page 239 is the only friction-driven metorcab with which we deal in this issue. This machine is made by the" Certus (Gearless) Company, Limited, of 48a, Gillingham Street, Eccleston Square,. S.W., and it is driven by means of a two-cylinder, to-12h.p. Aster engine..
The power is transmitted, from the engine to the rear wheels, through a pair of friction discs, a differential countershaft, and side chains. The driving disc is connected to the flywheel of the engine by a propeller shaft and a corrugated, sheet-steel, clutch plate, the latter of which is securely bolted to the face of the flywheel. One of our smaW illustrations shows this interesting detail. The corrugations on the plate serve a double purpose. First, they allow, by reason of the distortion of the corrugated plate, of the driving discs. beingwithdrawn from contact with the corresponding disc, and they act more or less as a universal joint between that part and the engine. The driving disc is. withdrawn by means of eccentric rods and eccentrics, the latter of which are mounted on a cross-shaft, and this is operated by means of a pedal.
Another of our illustrations shows the two friction discs, as viewed from the inside of the cab when the floor-boards are removed. The friction disc may bc. moved along the differential shaft, and the latter is provided with aelong, stout feather. The change-speed lever, with its quadrant, provides fc the driving disc's being temporarily .'ecured in any one of seven positions, s‘x of which are for forward driving. Both the shaft on which the driven disc slides and the differential shaft are mounted on ball bearings, and the thrust on the main driving disc is absorbed by a similar bearing of very large diameter. The construction of this vehicle is extremely
Pullear.
The only front-driven vehicle, amongst the 31 cabs with which we deal in the present issue, itthe Pullcar, which is manufactured by the Pullcar Motor Company, Limited, of Kay Street, Preston. The engine and the whole of the transmission gear of this chassis are arranged on a forecarriage,, which is steered on the fifth-wheel principle. The engine is situated underneath the driver's seat, and the crankshaft is parallel to the leading axle. The drive from the crankshaft to the gearbox shaft is by means of spur gear, ing,. and from the gearbox to the differential shaft it is transmitted through a silent chain. The gearbox provides two speeds forward and a reverse, and it is of the epicyclic type. The differential shaft is carried on the front axle, and the front wheels are driven through universal joints, the centre lines of which coincide with the centres of the leading wheels. This novel vehicle created a considerable amount of discussion at a recent meeting of the Institution of Automobile Engineers.
The arrangement of mounting the whole of the transmission gear on a pivoted forecarriage enables back wheels of very large diameter to he used, and these naturally tend to add to the comfort and easy riding of the cab. Pneumatic tires are employed on the front wheels, but solid tires on the back wheels have been found to be sufficiently resilient to insure smooth riding for the passengers.
The four-cylinder engine develops from 14 to toh.p., at its normal speed of goor.p.m. Foot levers are employed to operate the low speed, and the reverse, and these, being of the epicyclic type, are brought into operation by the application of band brakes. Starting from the left, the depression of the first pedal applies the top speed; the depression of the second pedal will bring the reverse into operation; and the right-hand pedal actuates the brake. On the top • speed, the drive is direct through a metal-to-metal cone clutch, which locks the crankshaft and the gearbox shaft.
Lotis.
A chassis, Jic1t properly merits separate classifi Lion, is the " -Lot's," a machine of quite unique features, produced by Sturmey Motors, Ltd. The works are si,ttiated at Widdring-
ton Road, Coventry. The designers have not allowed themselves to be trammelled by considerations of convential constructional practice. They have aimed at the production of a vehicle of maximum carrying capacity on a minimum wheel base.
The engine, which is of the unusual, inclined, twin-cylinder V-type, is located beneath the driver's font-board. With a deep-rooted objection to the employment of the traditional sliding gears in the change-speed mechanism, this Coventry maker has embodied in its design an epicyclic form of reduction. Whatever our opinion may be as to the necessity of superseding the simple sliding change-gears on these light machines, we must admit that, providing the clutches on the epicyclic mechanism are kept well adjusted, a change of speed effected in this manner is a soft
and efficient operation. The maker tells us that it costs nearly twice as much to fit these epicyclic gears as ii would to employ the ordinary form Poi sliding gear, but that it considers thf end justifies the means. Great store h set by the designers of the" Lotis " or the method of control employed, which it is claimed, effectively eliminates al possibility of a careless or ignoran driver's reducing the mechanism tc wreckage through mis-handling of th4 control gear. Two speeds only, in the forwan direction, are normally provided or these cab chassis, but the manufac turers are quite agreeable to fit a thin speed, if the purchaser considers th, local conditions with which he has t■ deal warrant such an addition to tb. standard design. This cab has an un usually large luggage platform.