From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'The Autocar' detailing the rigorous testing methods for vehicle components and performance, including endurance, brake, and handling analysis.
| Identifier | ExFiles\Box 160\3\ scan0230 | |
| Date | 10th February 1939 | |
| February 10th, 1939. The Autocar. SCOTLAND 217 Research by means of single cylinders—the “clinic” where various cylinder designs are tried. “ Third Degree ” The equivalent of pedal pressure. As the tank fills, the water flows into the annexe, puts the tank out of balance, and causes it to tip over and empty itself. Thus a pedal pressure is obtained which gently rises to a maximum, is then released, and then gradually builds up again, repeating the process without cessation if necessary. “ Physical Endurance ” Then there is the large R.{Sir Henry Royce}-R.{Sir Henry Royce} physical laboratory where luckless components are taken for test to destruction. Imagine the whitewashed interior of a large building, rows of queer machines along the sides, brilliant lights down the centre, and the ceaseless movement of gleaming cranks and wheels all around you. Here you see a silent sleeper, absorbing what must seem to it to be all the shocks in the world, there an axle shaft receiving irresistible twists from end to end, or perhaps a steering wheel having its rim persuaded to part from its spokes. Close to the floor over in that direction is a large connecting rod securely held at some points, and enduring intolerable squeezes on its big-end. Behind is a great metal box with windows, vapour issuing from a funnel in the top. Inside you can see a water pump apparently trying to pump the ocean dry. On your left is a steel cage covered with torpedo netting, which is placed over components such as flywheels or clutches when they are run up to speeds at which they may perhaps burst. One hundred and one tests are going on all the time, to ascertain the working life of this and that, to determine its factor of safety by pushing and pulling and prodding and twisting and rotating relentlessly until the truth is dragged forth. Every single new component has to go through it. To exact the truth, in its unity, about certain aspects of road performance, a most intriguing instrument has been devised and is in regular use. It consists of a chronograph with a choice of some four recording pens which apply their marks upon a moving strip of paper. Suppose an accurate brake test is required. The instrument is placed in the back of the car, and electrical contacts are provided on the brake pedal and on cams attached to the road wheels. The clockwork of the chronograph moves the strip of paper. One pen makes a mark for every second. The car is driven at the desired speed, and the second pen marks each revolution of the road wheel, or a part thereof, on the paper. The brake pedal is applied, and the third pen records the exact happenings of a complete stop are marked down. When the strip record is examined it shows all details of time and distance, and thus provides unassailable testimony of the whole of that test deceleration. Acceleration can be accurately measured by the same instrument, and it eliminates speedometers and human error. It was made to R.{Sir Henry Royce}-R.{Sir Henry Royce} specifications by the Cambridge Scientific Instrument Co., and adapted by the test section to their needs. Besides this extensive physical laboratory, there is also an electrical laboratory, wherein research into present and future equipment is carried out. It is not generally known that Rolls-Royce and Bentley make their own dynamos, starting motors, distributors and coils, and do it with that care for details so typical of their search for durability. If you make a car with no real springing and fit the wheels with extra hard tyres, it may perhaps go round corners at high speeds exactly in accordance with the movement of the steering wheel. But if you desire a car which has pre-eminently comfortable springing and soft tyres, and safe into the bargain, and you expect to be able to drive equally fast and steadily round curves and corners, the proposition is much more difficult to tackle. As an example of extremes imagine a car on full lock being driven round at a speed of 2 m.p.h. The car will follow its steering fairly accurately, but if the speed were increased to 20 m.p.h. it would begin to roll and the tyre treads to creep, so that the turning circle became much greater and the vehicle would be to a considerable extent out of control. In order to study this waywardness, and thereafter exorcise the evil influences which cause it, Rolls-Royce and Bentley have constructed a large concrete arena about 80 yds. in diameter at a cost bordering on £4,000, which is called the “skid pan.” On this flat surface the problems of under-steering and over-steering are examined. “Under-steering” means that when rounding a fast curve the front of the car has the greater tendency to swing outwards, and hence the driver has to increase the helm he is applying. “Over-steering” is brought about when Testing frame torsion—“thumbscrews” are being applied to a competitor's frame. A 31 | ||