A British Designer Looks in at the Paris Show
Page 59
If you've noticed an error in this article please click here to report it so we can fix it.
Striking Appearance of Passenger Vehicles Among Most Outstanding Features, No Major Developments of a Mechanical Nature, but Much Interesting Detail Work BROADLY, this year's exhibit of commercial vehicles at -LP the Paris Salon may be summarized as representing efforts to produce vehicles of large carrying capacity, and the adoption of the oil engine for both light and heavy classes.
It is of extreme interest that many of these power units incorporate English practice, being made under Gardner or •Ricardo licence. This seems highly commendable, in view of the early lead obtained by our continental friends in the compression-ignition field.
One of the outstanding features of the Show was the fact that there have been concentrated efforts to produce large passenger vehicles of striking appearance, with well-raked fronts, curved radiators, grilles and imposing mud wings. It would appear, in fact, that vehicle designers, in competition with their car confreres, have gone " all streamline." However, whilst these features are highly desirable, they do not appear conducive to accessibility or increased carrying capacity.
Neat Oil-engine Design.
The oil engines, which I closely inspected, especially thosd of recent design, present a clean external appearance and are considerably lighter, than the units previously manufactured. Torsional vibration dampers are fitted in most It was of interegt to note that the dynamo in practically every case has at last been mounted at the front of the engine, in the air Stream. from the fan, where it is adequately cooled. This arrangement has been made possible, in many cases, by placing the timing gears at the rear. On some engines the dynamo is positioned in line with the fan, Double or triple V-belt drives for fan, pump or dynamo are generally adopted, so eliminating belt slip at the higher engine speeds—a trouble so prevalent in the pest.
Radiators, in practically all cases, follow private-car practice, having a sheet-metal tube block surmounted by a grille. Whilst being artistic, they are hardly likely to prove so serviceable as the type usually in vogue in this country.
With regard to frames, there does not appear to be much standardization, most manufacturers having apparently their own views on the matter. Samna., Panhard and Chenard-Walcker showed welded frames, and it cannot be disputed that these give a clean appearance, and, in my opinion, a measure of durability far in advance of the bolted or riveted type, because the contact at the weld is distributed over a large area.
Variety in Frame Construction.
Panhard and thenard-Wakker had on view welded Flsection frames, whereas the Samna is of the channel type, with its cross-members butting well to the inside face, Two tubular cross-members, of approximately 9 ins, in diameter, are also attached fore and aft.
A cruciform-type frame was exhibited by only one maker. Others showed frames with top and bottom plates riveted to the main member, a method which would appear to be costly. It seems that higher speeds and heavier loads have again produced problems. I noticed a chassis which had three large box-section cross-members measuring approximately 9 ins. by '2 ins. formed of sheet metal, On the other hand, Lorraine displayed a 5-ton vehicle Of the Tatra type with a central tubular member of about 9 ins, in diameter.
Road wheels, in general, are of the demountable-rim type, incorporating a cast-steel centre, having semi-circular spokes. There appear to be no important changes in the design of front axles, although I noted small advances of a detail nature. Almost every vehicle is equipped with shock dampers. Double-reduction back axles appear to have been widely adopted, especially in the heavier classes. They employ spiral gearing and are of the fully floating type.
It is strange that the worm-driven axle has encountered little favour in France. I saw Only one of this type. Nothing new in clutches attracted my attention.
Opinion seems to be equally divided between unit construction and separate gearboxes. In the case of the latter design it is not so clean as might be desired, there being in evidence too many levers and linkages which must eventually result in wear and backlash.
Universal joints between gearbox and axle are mostly of the needle-roller variety, or made to the manufacturers' own designs. Rubber discs are freely used between the clutch and the gearbox, when independent construction is employed, although on one chassis I observed a steel-plate coupling.
Transmission Brakes Popular.
Transmission brakes are well to the fore, presumabl1. because of the extremely wide brake drums on the rear wheels, Ratchet or windlass-type hand-brake levers are adopted by many manufacturers; they have the advantage that plenty of slack is permissible in the brake connections. It is of interest to recall that this type was put forward and illustrated in The Commercial Motor in 1912.
Brake connections vary, some being of the tape type, others rods or steel cable, or a combination Of both.
Compressed air is popular for brake operation, although the Dewandre vacuum-servo type, also the Lockheed hydraulic system, are well to the fore.
The WilIeme concern exhibited a neat arrangement of braking on itj 9-tonner. Two air cylinders are mounted above the rear axle casing, the pistons being coupled to levers on the rear fulcrum shaft.
Another neat attachment was to be found on the Delahaye chassis, in which the servo motors are mounted at each side of the frame and are coupled to the brake fulcrum lever by rods approximately 3 ft. long.
Most vehicles employ the Hotchkiss-type drive, only two exhibits having torque tubes and spherical joints.
Sliding-pinion gearboxes predominated, but manufacturers have largely adopted the silent third gear.
Unusual Driving Position.
Renaults displayed a Scemia bus chassis, in which the driver's seat is mounted above the engine. The latter struck me as being inaccessible owing to the extreme width of the chassis.
Whilst the Exhibition was most impressive, from a spectacular point of view, I do not consider that it can in any way compare with our o,...+n Commercial Motor Show. British design is cleaner, sturdier and better standardized, yet it bristles with many more proved innovations, The lack of outstanding features at the Salon may be due in some measure to the political and financial difficulties which at the moment are besetting our neighbour across the Channel. On the other hand, however, French conditions of operation as regards speed, loads, etc., are totally different to those obtaining in Britain.