W. A. Robotham, who is in charge of the Experimental Department of Rolls-Royce, Ltd., describes the very thorough tests which have helped to ensure Rolls-Royce and Rolls-Bentley perfection and some amusing incidents associated therewith.—Ed.1

SELLING motor-cars from ta ,500 upwards may be a very satisfactory procedure from the sales department’s point of view, but it Undoubtedly throws severe obligations on the engineering department. The cutith flier — somewhat naturally—expects to have complete reliability and almost infinite durability from such an expensive product. A story is told (which I believe can be substantiated by facts) of a Rolls-Royce customer who, during a motoring holiday with his family, experienced a broken valve spring. He immediately put up at the best hotel within reach, telephoned to Derby, and awaited the arrival of a mechanic with the replacement spring. The company was afterwards asked to settle the hotel bill, whilst, of course, the mechanic’s services and travelling expenses were supplied gratis. In contradistinction to this somewhat autocratic attitude, the owner of the more moderately priced popular car might be expected to call at the nearest garage for a replacement spring. I once asked the managing director of a firm making ” popular ” cars if he had any service valve spring trouble, but he knew of none nor did his service manager. Further investigation, however, revealed that the Storekeeper disposed of thousands of valve springs annually to the company’s retailers.

The problem of satisfying the purchaser of an expensive motor-car is bad enough when the vehicle lays no particular claim to have an outstanding performance, but it becomes worse when the high-priced chassis is supposed to be in the ” sportsear ” class. The obvious reason for this is that if a car has any real performance it can, like a thoroughbred horse, be very easily abused. If, in addition, the car holds the road well, has effective brakes, an unobtrusive power plant and a gearbox that is quiet on the intermediate gears, it is the simplest thing in the world for the unmechanically minded and inexpert driver to do irreparable damage by unintentionally driving in third gear instead of top.

We rarely get any serious trouble from experts like Raymond Mays, E. R. Hall Or EySton, although they frequently use their towing Bentleys for practice under racing conditions, quite apart In ‘in getting the maximum from the vehicle under ordinary touring conditions.

From the foregoing it will be appreciated that no amount of experimental testing can ensure 100 per cent. satisfied owners, but it does seem that the somewhat strenuous schedule adopted by RollsRoyce, and outlined hereafter, has enabled the Rolls-Bentley to satisfy quite a number of people. Since the days when the ” Silver Ghost ” competed with success in the Alpine Trials in 1913, Hulls-Royce have favoured the Continent as a provingground for their products. It was not, however, until after the last war that we set up a permanent establishment in France from which to run continuous experimental tests. Sending a car seas has one great advantage— it .gets ars ay from the factory and calls a halt to the process of fitting new and alleged “improved ” pieces. Apttrt from this, for fast road-work, poor surfaces and mountaineering there is no comparison between the terrain of the British Isles and that of the Continent. It is necessary to supplement Continental testing with running under London traffio conditions, as this throws a peculiar strain on the clutch and transmission anil also empha sises over-oiling and overheating under idling conditions. Such tests, therefore,

are always included in a standardisation schedule of mileage, which tit the outbreak of war consisted of the following :25,000 miles on the Continent (including a comprehensive tour in the Alps).

1,000 miles in London traffic. When we first At:tied our Continental tests it was on a basis of 10,000 miles running, but as road surfaces improved and the standard of reliability expected by the customer increased, we steadily raised the distance to be covered. The average speed of this Continental running is very high, and our records show that

it has progressively increased in spite of the fact that there is probably ten times as much traffic on the French roads to-day as there was 20 years ago. This, of course, is simply an indication of the improved roadworthiness of the car and the increased engine performance. The Continental running is not confined to running-miles alone ; the test station is fully equipped to dismantle the chassis, and when troubles occur—as they are bound to do on all experimental cars – it is up to the staff to recommend a solution to the design department. To do this they frequently have to call upon the engineers from the Derby factory, who travel out to investigate the problems. This investigation work often takes quite

as much time as the actual periods when the car is on the road. Generally speaking, four complete tests are run every rear. It is exceptionally difficult for the testers to avoid occasional accidents. I well remember that -when we first started these tests, although other motorists were few and far between, the hazards of the roads were very considera t il about 1028 the livestock of every farni adjacent to the road made a practice of using this level stretch of ground for recreation. To cover a test-run of 500 miles without some sort of fatality was the exception rather

than the rule. The roads were, of course, untarred in most eases and, in consequence, in wet weather it was not always possible to stop very hurriedly. On one occasion when I was it ri ving one of these test-ears and we had slowed down to about 40 m.p.h. to go through a village a sow of unusually large proportions attempted to cross the road. It was obviously a question of either hitting the sow or a poplar tree, and we, therefore, chose the sow, striking it very close to the tail with the dumbiron. Almost immediately the car was surrounded by a

crowd of gesticulating villagers, who appeared to spring from nowhere, a-nd somewhat heated argument ensued. Any conversation which I have in French is likely to cause misunderstanding and this particular instance was no exception to the rule, since I kept emphasising that le cochon was mort, and a shrivelled old lady, who appeared to be the owner of the sow, would keep referring to it as une truie. We rapidly came to an impasse, which was only surmounted when, by mutual consent, we adjourned to the domicile of the pig-keeper, where I was shown ten small pigs ! No pains were spared to describe the probable death agonies of the infants, robbed of maternal care. However, the clouds lifted somewhat when we got back to the car and found ” mother ” uneasily cantering down the road. The next day I received a bill—a copy of which is printed below—for 1,000 frs.-500 frs. for the mother and 50 frs. for each petit porrel et—which was so obviously a ” try-on ” that I retaliated by another bill for 1,000 frs. for ” damage done to the car.” Before rendering this I took the preeaution of having a very considerable party with the local gendarme . The matter a as satisfactorily ” settled out of court “—no money changing hands!

Another catastrophic accident occurred when one of our drivers ran over ten turkeys at once. The mortality would have been reduced had not the turkeys been walking in line along the edge of the road, which was not sufficiently wide to admit the passing of two vehicles. Had the Continental test section had all its victims stuffed and put in a museum the result would have provided an astonishing spectacle. Not the least of the problems in the early days was that of dust. It is no exaggeration to say that in the summer on certain roads the cloud of dust half-amile behind the car was 80 thick as to completely obscure visibility. The French cyclists, who abounded then as now, showed little appreciation of our activities, and we had to be careful not to use the same road too often. The level-crossing keepers soon came to know us and, in

common with all other employees of the French railways, showed a distinctly sporting instinct. They were always ready to appraise the speed of the approaching train and, if the odds were at all reasonable, took a chance that we would cross the line before the locomotive passed between the gates. The fact that we never hit a train testifies to their sound judgment.

Round about 1925 wheels and tyres were very troublesome. The straightsided rims, which were held on by being sprung on to the wheel, used to come off at maximum speed, whereupon the tyre left the rim and the first indication of trouble which the driver had was that the car became somewhat uncontrollable. It was always difficult to find the rim, although one could usually keep an eye on the tyre as it bowled down the road ahead of the car.

In really hot weather when driving fast on bad roads, which were the rule rather than the exception, tyre-life was very unsatisfactory. I remember leaving a town about 100 miles south of Orleans at 10 o’clock in the morning to run someone to iDieppe and then go on to Paris. I started with a brand new set of five tyres and ran into Paris about 11 o’clock at night with one cover stuffed with hay. It is difficult to over-estimate the value

of having straight, traffic-free roads available for experimental testing, and when, in addition, one is no longer worried by the production departments at the factory it is surprising what useful work can be accomplished.

We had one rather puzzling problem when we first introduced four-wheel brakes on the “Silver Ghost” RollsRoyce. We found that the average petrol consumption over roads which we knew well had dropped by over a mile to the gallon, which, since at the time we were getting only about 11 miles to the gallon, was something which could not be disregarded. The modifications which we had made to the engine in fitting these brakes were insignificant, being confined to a new exhaust manifold. The gear-ratio and the weight of the car remained unaltered. The poor fuel economy, therefore, appeared to be inexplicable. As a last resort, I instructed the drivers to carry out a test-run using nothing but the handbrake, which operated only on the rear wheels. Our mile to the gallon was at once recovered, showing that good brakes increase the average speed of the car and so the fuel consumption. Experience shows that if the bearings of a car will stand up to 20,000 miles of this Continental test they will have a life of 50,000 miles in the hands of the

ordinary British customer, who only crosses the Channel occasionally. The German motor roads have presented an entirely new problem, which has been dealt with by the production of the ” Corniche ” Bentley, the evolution of which was recently described in MOTOR

SPORT. If customers take standard Bentley cars on to the autobahnen they must restrict their sustained maximum speed to about 80 m.p.h. if they do not wish to reduce the life of the engine considerably. We do not apologise for this state of affairs. The winding roads of Britain require a rather specialised type of vehicle and, until they are brought up to date, the standard British car is bound to be much under-geared for modem automobile highways.

As may be imagined, the records of a million miles of Continental motoring provide an immense store of knowledge for future design work. The incidents— humorous and otherwise—which occurred during this testing would fill a book. For the time being, the overseas test section of the Rolls-Royce Experimental Department has, of course, had to close down As soon as the war comes to an end, however, it will re-open, because we believe that, in the past, it has been in a large measure responsible for such degree of reliability as we have attained with our products.