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8th December 1925
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Page 11, 8th December 1925 — PRELIMINARY NOTES ON THE BERLIN SHOW.
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Leading Features in German Des-gn; Rigid-frame Six-wheelers; Low Frame Levels ; Six-cylinder Engines ; Four-wheel Brakes ; Double-reduction Axles and Light Metals for Wheels, Cylinder Heads and Brake Shoes.

wE must confess that the comtnercial vehicles and chassis which last week occupied one of the three large halls at the Berlin Motor Show have caused us mach surprise and afforded much food for thought, on account of the advanced stages of design displayed by them. There are still many somewhat crude examples, whilst certain of the new products appear something in the nature of freaks, but there is undoubted proof of strenuous efforts to reach the forefront and, in almost every way, the changes effected on the designs for Olympia are reflected here. It is almost startling, for instance, to learn that nearly 500 Bussing six-wheelers are in active operation, not only in Germany, but also in Sweden and other countries, and that a much. improved low-built model is now available. Thjs. will be used mainly for passenger transport, and the older type will be relegated to carrying goods.

So far as competition in the British market is concerned there is, at the moment, little to fear, for the German makers have not built to regulation and but few of their passenger vehicles would meet the requirements of our authorities, particularly in respect of clearance.

One particularly important point is the great attention which is being given to the employment of lighter materials

elektron, silumin, duralumin and other alloys were to be found in great quantities, not only on the stands of those marketing diem, but actually on the vehicles. The saving in weight can be enormous, and huge cast wheels can now easily be lifted by one man (the tubular-spoked elektron weighs 32 kg.), which means far less unsprung weight and a consequent saving of the roads, which vital transport factor will also be influenced by the-ahnost general use of pneumatic tyres on everything up to five tons and some above that weight. The largest tyres we noticed were 40 ins. by 10 ins, and, naturally, the majority are of Continental make.

We had expected to find considerable progress in the use of Diesel engines, but, despite the fact that many concerns have done much experimenting, there was only one chassis shown with this type of power unit, this example being a M.A.N. of 45 b.h.p. to 50 b.h.p. The M.A.N. engine is a really neat unit, which is started by a Bosch machine mounted above the gearbox. The oil is supplied to the cylinders by a small four-cylinder pump driven from the timing gears and connected by small-bore pipes to the injector valves.

There are many difficulties to be overcome in the designing of a small-type Diesel motor, of which the greatest is to make it sufficiently flexible in its speed capabilities. It is fairly simple to design for a constant speed of, say, 800 r.P.m., but the problem is to raise this or lower it when required, for the quantity of liquid fuel to be injected at each firing is most minute and does not lend itself to easy control—the slightest wear causing appreciable differences in running. In this connection it is of interest to note that the Benz Diesel motor, which was popularly supposed to have great potentialities, hag been dropped, so far as road vehicles are concerned.

Of the many new chassis the most remarkable is undoubtedly the low-framed D.A.A.G., which can be supplied with a four-cylinder engine of 60 b.h.p. or a six-cylinder unit of 80-100 b.h.p. The frame is downswept at the dash and raised over the axle ; it has side members of box section, 11 ins, in depth, welded from plate and with a channelsection tension member, with the open part down, welded into the lower part of the box. All the rivets are hollow and resemble boiler tubes with the ends splayed outwards; within the side members each is surrounded by a tubular distance piece. This form of riveting is used throughout for spring brackets, etc.

The power unit is a six-cylinder with overhead valves

operated through tappets and rockers, the cylinders are in a block, but the heads are in pairs. Tandem drive is employed for water pump, Bosch dynamo and magneto. The final drive reminds us forcibly of the old-type Austin except that a separate casing is employed for the differential. This is carried at its front end by a spherical housing on a crossmember, whilst extension tubes bolted to the differential casing extend to the wheel centres, and in them are the two driving shafts with bevels at each end.

The whole axle assembly is constructed of 8 ram. steel pressings and weighs, without the Fischer steel wheels, 510 kilos.; it reduces the unsprung weight and also serves as a torque and radius rod. It is interesting to note that British Timken bearings are used throughout this chassis.

We have not yet exhausted its novel features ; the springs, for instance, are arranged in pairs of quarter-elliptics at each side, stretching inwards towards the axle and resting on slides on the last-named ; in the case ,of the front axle, this is tied to a universal joint on the front cross-member by a triangulated radius rod.

Both the clutch and the four-wheel brakes are operated through hydraulic cylinders, the plungers of which replace conventional pedals. A third cylinder affords a means for replenishing the control cylinders with oil. It is placed into connection with them through a neat hand-operated valve. The hand brake acts on the rear-wheel shoes through broad steel tapes.

Reverting to the springs, these are all arranged in their brackets so that their effective length shortens under load, and they are consequently progressive in their action. Tfie drive to the differential is taken through a two-piece propeller shaft with laminated steel joints.

It is claimed that the special back-axle construction gives good clearance, both between axle and road and between axle and body.

The hollow-sided triangle forming the driving unit is provided with vanes so arranged that when they are revolved the lubricating oil is kept circulating round the triangle.

The height to the top of the frame is 67 cm. This is with 36-in. by 8-in, pneumatic tyres, but 38-in. by 0-in. can be fitted.

Another exceptional chassis is the six-cylinder N.A.G. lowframe model, with side members humped over the axle and with platform extensions at a much lower level. The engine has two blocks of three cylinders with side valves, sparking plugs set horizontally, pump cooling and oval radiator with detachable vertical honeycomb blocks of different lengths and the silencer underneath it. Front-wheel brakes of the Perrot type with adjustment by adjoining serrations are employed. In the model exhibited, which is the Berlin type for open and enclosed double-deckers, the front axle is set back some 4 ft. to allow a shorter turning circle. In the ordinary course this makes driving difficult, as the wings are no longer a guide, so a wide spring bumper with upturned ends of the same width as the vehicle and visible-to the driver is fitted.

A quadrant change-speed is used, but there is a neutral position between each two gear positions.

An unusual point is that the drive to the two-cylinder air pump is obtained by sliding a bronze pinion into the starter ring of the flywheel. Also the internal-clutch cone is faced with compressed paper fibre—a war-time expedient which has proved so successful that it is preferred to a friction fibre. Hardy_ type discs are used on the clutchshaft, which is long, but is moved bodily forwards to press out the clutch cone ; in doing so it brings a clutch brake into action.

The aluminium gearbox is carried on two dropped crossmembers and there is a loco-type foot brake, behind which is an enclosed Hooke's joint and open propeller shaft taking the drive to a bevel and spur double-reduction axle in which the line of drive is dropped about 6 ins, below the axle centre line. Two large rubber-ring bumpers are mounted on each spring carrier of the axle.

Cast-iron shoes are used for the rear brake, but each of these shoes is bolted to a special carrier and can thus be easily removed.

In a heavier-model axle, which was shown separately, a triangulated torque member with a ball-end is secured to the axle and has a cross-member in which the forward position

of the double-reduction case is carried. Double-row ball bearings are fitted in the wheels. This axle is, used on a 5-tonner which hauls two 5-ten trailers, but in this case the axle is reverSel, so that the drive line is above, instead of being. below, the axle centre.

At this point it may be of interest to refer to the fact that the majority of the axles are of the double-reduction or dual type. Worm gearing is only used in a few vehicles.

We have already feferred briefly to the Bussing six-wheeler

and its success. The new model has a frame height of 60 cm. It is practically identical with the 5-tonner, except that two shafts take the drive from the gearbox to the two axles at the rear end. The longer shaft is carried in a steady bearing. Each axle is an ordinary single-redaction type, with,, a torque tube ending in a ball carried in a spherical housing on a cross-member and mounted at the ends of two rocking beams carried by fulcrum brackets bolted to the centres of two laminated scull-elliptic springs.

The advantage of this method of construction is that each axle drives direct to the frame, so that there is no tendency to tip a semi-bogie. The springing remains compensated and, the axle " centres " being well offset, can be accommodated more easily under seats or extended wheel arches. The wheelbase is 5 tn. 62.5 cm., but a six-cylinder model with 6 m. 62.5 cm. is also made.

It is this six-wheeler which has the 40-in. by 10-in. Continental pneumatics.

Bussing have also produced a special low-framed chassis for Berlin buses with covered upper decks. A feature of this chassis is its very light weight, attained partly by the use of Elektron metal for such parts as brake shoes.

Many • other new and interesting chassis and vehicles will be dealt with in our next issue. some of these are illustrated now.

An interesting development of thewell-known Wood tipping gear Was to be seen for the first time. The cam pieces, which were formerly secured to the underside of the body, are now pivoted on the same fulcrum bar as is the body. The cams merge into a socket carrying a ball and, when tipping to the rear, no difference is to be noted, but, when the body is held at one side and released at the other, the ball, in lifting, slides along a curved steel track on the body and lifts it absolutely smoothly. To take the side stresses the parts have been suitably strengthened.


Locations: Austin, BERLIN

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