THE HOME OF CRAFTMANSHIP
THE BUILDING OF ROLLS-ROYCE CARS.
BEHIND an institution as famous as that of the Derby works of RollsRoyce one always finds an interesting history. Even to deal briefly with the present-day routine of manufacture
of the world-renowned cars requires a lengthy article, so nothing more than an outline of the foundation of the firm can be given here, leaving the sporting and technical development of the cars to be treated at a later date. The story opens with Mr. F. Henry Royce who was engaged in making high
grade electric cranes in Manchester. Finding that the competition of lower priced goods from the Continent had undermined the market, he turned his attention to the making of motor-cars. From experience gained with various makes which he had owned and tried, he found out the various faults which beset them, and his first production, a two cylinder car which appeared in 1903, showed such an appreciation of the finer points of control, finish, and silence that
it equalled the four cylinder machines of the day and drew unstinted praise from all who tried it. The Hon. C. S. Rolls, whose name later became the first of the two in the famous ” R.R.” monogram, was at that time running a motor agency in London, and recognising at once the merit of the Royce
cars, arranged to take the entire output. His racing and. commercial experience supplemented the engineering knowledge of Mr. Royce and the cars appeared successfully in all sorts of competitions.
Royce cars were second in the 1905 T.T. race, and first in the race of 1906, and. the business expanded so rapidly that in the following year the Rolls-Royce Company was founded, with plans for moving to Derby to an enlarged factory. The move was completed by 1908, the factory buildings, like every other matter appertaining to the cars, being designed by Mr. Royce. Their area at that time was about one acre, which has grown steadily year by year,‘ncreased of course also by the space required for manufactur
ing aero engines, till it now totals about 16 acres, and between five and six thousand workers are employed there.
Of the firms, two founders, only one remains. Charles Rolls was killed flying at Bournemouth in 1910, though not before the Rolls-Royce car had gained recognition as the world’s supreme automobile production. Sir Henry Royce, who was knighted by the King in 1931 after the Schneider Trophy in recognition of his services to British Aviation, still remains Engineer in Chief, and apart from the new designs and improvements which he still originates, no new departure appears on a Rolls-Royce car or aero engine until it has passed the scrutiny of the engineering genius whose attention to the smallest detail has made the car supreme.
In order to retain complete control of the quality of the components, every part of the Rolls-Royce car, excepting a very few specialised accessories, is made at the L erby factory. The first department we visited was the aluminium foundry, where crankcases, gear-boxes, and various smaller components were being cast. The various alloys are delivered in pigs, and are melted in great oil-fired furnaces, around which red flame is always licking. The molten metal looks rather like solder, and is poured from the furnace into a fire-clay vessel with long handles and is then taken by two men to the place where the moulds have been set up. The temperature of the molten metal is determined by means of a pyrometer, and when it has cooled to the correct pouring heat, the jar is tipped and the
silvery looking metal is poured steadily into the mould until it appears through all the vent holes. The correct pouring temperature has a great influence on the properties of the casting, and proper venting of the moulds is essential to avoid blowholes and weak spots. The moulds and cores are works of art in themselves, the surfaces being finally smoothed over with a mixture of French chalk and water, and the castings when they appear are so smooth that they only require the minimum of cleaning up. We were unlucky in our visit to the iron foundry, as the actual casting is carried on only on alternate days. Instead we saw cores and patterns being made. The men engaged in making the former become so skilled that they can work almost without having to refer to drawings or patterns, their sense of touch
Av.es which shows a centrally driven lathe machining car crankshafts.
becoming so highly developed. The making of moulds is an equally skilled job, and the expert can transfer the imprint of an incredibly complicated pattern to comparatively crumbling sand. Cylinder blocks are the most important components which emanate horn the foundry and the Rolls-Royce engineers have evolved a special chilling treatment which makes the bores unusually tough. They are finished by honing and outlast the car without showing signs of wear. The drop-forging shop is one of the most striking features of the Works. Coming in from the daylight, at first all one can See is the glow of the gas furnaces, where the steel is being heated preparatory to being forged, and the dim figures of men grouped round glowing pieces of metal on the anvils of the drop hammers. The hammer descends and the metal alters shape. It is taken to another anvil where it is hammered between dies of a different
shape, then to a third where the surplus metal is trimmed off. Back again to the first, an application of gauges and a final blow and the finished part, now seen to be a valve rocker, joins the pile below the hammer. The operators develop an uncanny skill in controlling these ponderous tools, and as in the case the foundries, the parts, steering arms or whatever they may be require little more than cleaning up to bring them to the right side.
The two-ton steam hammer which was housed in the same buildings as the drop hammers was even more impressive, flattening a six-inch billet into a mushroom shaped forging ready for making into a propellor boss with a couple of blows which shook the building. In a nearby bay we saw the first signs of anything which suggested car construction. Side members for the various
chassis were arranged on the floor and were linked up by the front and rear cross members. Then each in turn was laid on -a suitable platform, a cord was run from the centre point of the back crossmember to the front one, and the process of checking alignment began. Before the holes are drilled in the side-members, the dimensions of each is checked and those which are not perfect are rejected. Once again when the side members have been connected, the unhurried inspector with his trammels measures up the distance either side of the centre cord a score of times, and it is not until he has satisfied himself that every part of the frame is symmetrical about the centre line that it is allowed to return to the erectors for the fitting of the sturdy tubular cross-members which re-inforce the centre part of the frame. Almost every tool in the machining shop, which comprise anything from auto
matics making nuts and bolts to milling machines for finishing crankcases and the like is worthy of mention, but we can only refer here to a few.
The finished Rolls-Royce crankshaft is a beautiful piece of work, machined all over. It is first turned on a centrally driven lathe, and the webs are then ground all over by a more than human machine in which the grinding wheels swing backwards and forwards as the crankshaft revolves until the exact contour is reached. Cams are ground on camshafts in the same way, the rocking arm carrying the grinding wheel following the shape of a master cam at the rear of the machine.
The centre of the crankshafts are drilled, also the camshafts, using drills about four feet long. This centre passage is used as an oil channel, and also lightens the components.
The big-end journals of the crankshafts are also hollow, the three throws being drilled simultaneously. Channels are then drilled through the webs to carry the oil from one journal to another, and tapered aluminium caps close the outside of the holes through the journals.
An immense amount of care is devoted to perfect gear-cutting, and the teeth of every gear-wheel are ground all over. The formation of bevels is a most interesting process, etas being taken from either side of the tooth by two knife-shaped cutters, which work in an inch-wide jet of oil, and when they have finished the formation of one tooth, lift up and pass to the next. The gears are then heat-treated to normalise any stresses which may have arisen in machining, and are cooled in oil-baths under pressure to prevent them warping. Then like the straight tooth type they are taken to the grinding department, where thin specially shaped stones bear on all the working surfaces. The grinding wheels are re-faced after each gear has been treated, in order to make sure that they shall not vary, and in the case of the timing wheels, the teeth are finished off by hand to ensure complete silence of operation.
Checking for accuracy.
Although the material from which the various engine and other parts are made is very carefully selected, and samples from every batch undergo tests in the laboratory, slight flaws are bound to occur, and in the machine shop as in every part of the factory, a considerable part of the department is devoted solely to examination of each article which is used. Each component is checked with delicate gauges and micrometers and every part of it examined under a magnifying glass. Even this scrutiny cannot always detect hair-cracks almost invisible to the human eye, so additional tests are undertaken. In the case of material such as iron or steel, which can be magnetised, the part to be examined is placed within the field of a powerful electric magnet. It is then dipped into a bath of paraffin containing very finely divided iron filings and taken out and allowed to dry slightly. If there are any flaws in the metal, the iron filings collect along the line of the defect and
reveal the otherwise undetectable weak spot.
This method of testing is of course not applicable to parts made of non-magnetic metals, such as brass or aluminium. In this case the object to be tested is placed in a bath of warm oil, and then as much as possible is wiped off. French chalk is dusted over the surface, and in a short time any crack which may exist is revealed by an oil speck in the chalk dust. The Cloudburst process is used for checking over the hardness of such components as valve rockers and it also increases the hardness produced by heattreatment. The rockers are clamped with their hardened surfaces upwards under a vertical shaft, and steel shot is allowed to fall continuously from predetermined heights. The slight hammering effect caused by the falling shot closes up the pores of the metal and increases the hardness. On the other hand if the heat
treatment has been unsuccessful, the falling shot produce a mottling effect which is easily detected by the practised eye.
The next stage is the engine-assembly shop, and here unhurried workmen erect the engine and gearbox units. “Always be certain,” said a notice-board, and. ” above all thorough” said another. The finish of all the parts is amazing and we stroked them out of sheer admiration. The crankshafts are especially notable, and those used in the 25 11.p. engine are fitted with balance weights owing to the higher speeds at which this engine runs. Crankcases and gearboxes have a peculiar brown appearance inside. This is caused by the boiled-oil process, which seals the pores and prevents the formation of the sludge which one usually gets on new cars. In another part of the shop, car steeringgears are being “run in.” The worm is first of all polished with French chalk and then its shaft is fixed vertically in a machine which rotates it alternately first in one direction, then the other. The nut which is the other steering member is
threaded on, and then weights totalling nearly half-a-ton are fixed to it. With chalk and oil as a lubricant the worm is rotated backwards and forwards, raising and lowering the weights each time. After a period of such treatment any stiff spots are eased, giving light and perfect steering throughout the life of the car. After the engines have been erected, they are given a five-hour run. A continuous supply of oil is forced through the bearings, flushing out any foreign matter, and is cleaned and filtered before being used again. Coal gas is used as the fuel, to avoid any chance of washing the oil from the cylinder walls. After this flushing process the engine is taken down and the parts washed and examined. Coming satisfactorily through this inspection, the unit is re-assembled and brought to the engine test house, where it is given seven hours’ running. Horse power readings are taken at various speeds. The
” 25 ” gives 85 h.p. at 3,500 r.p.m. and the Continental about 135 at 2,500, which goes far towards explaining its phenomenal pick-up on top gear.
The gear-boxes are built up with the same care as the engine, particular attention being paid to silent running. They are then fitted to the engines, and the unit is erected into the chassis, ready for the chassis dynamometer test. In this the chassis is fitted with solid tyres at the rear, which bear on steel drums. The shaft on which the drums rotate can be braked to varying extents by adding or removing weights to balance the pull exerted. The chassis is fixed in position with chains and blocks, and the engine is then started. It is tried in turn on all gears, and the readings attained show up any tightness or other defect in the transmission. As in every other department of the Rolls-Royce works, the most extreme precautions are taken against errors of any kind, and the barometric reading, the diameter of the driving tyres, and the variation of tension of the brake band are all allowed for.
. After the dynamometer test, which is equivalent to about 100 Tiles running, the chassis is allowed on the road for the first time carrying simply a seat and a wooden box which contains weights equivalent to that of the body for which the chassis is intended. In this way the tester is able to find out whether springs of the correct stiffness have been fitted, in addition to the usual carburettor and other adjustments which have to be made on a new car. After 150 miles the car is brought in again and fitted with a special body known as a test-rig or more disrespectfully “bread-van,” designed to magnify any mechanical noises which may be present. It is taken over the worst possible roads for 50 miles, and if no complaints are forthcoming the car then passes to final test, where a similar trial takes place. The Quality Department refuse to pass a car which does not seem to them perfect in every respect, even if it has gone successfully through all the preliminary tests, so that when a Rolls-Royce chassis receives its final approval, it is as perfect as human skill and craftmanship can make it.
Any article on the Rolls-Royce Works would be incomplete without a mention of the aero-engines produced there. The standard of workmanship used in manufacturing the cars is so high that no special precautions need be used in making the aircraft units, and the same tools and the same operatives work indifferently on one or the other. The engines are tested in a great row of test-houses, and even when their exhaust gases are led away through enormous water cooled silencers it is almost impossible to hear oneself speak and the testers wear cotton wool in their ears. Nearby are special open air test beds which can be tilted or inclined to give the conditions under which the engine works in the air, and tremendously strong wire torpedo netting protects workmen from the possibility of a broken propellor.
Radiators and Tanks.
In an article of this length it is impossible to do justice to the various subsidiary activities which play a part in the perfection of the cars, but one must mention the tank shop, in which sheets of tinned steel are double-rivetted and sweated to form the immensely strong petrol tanks and other articles of this sort. The famous Rolls-Royce radiators are also made at Lerby, dozens of copper tubes being fitted in a frame and dipped in molten solder to a depth of inch, the same treatment being then given to the other end. The tubes are hexagonal at the ends and circular in the centre and have a series of projections inside. These projections break up the air stream and greatly improve the efficiency of the radiator.
Every department of the Derby Works reveals its own example of the care and skill which go to the production of the finished car, and the elimination of any possible sources of trouble or wear. The silence, long life, and perfection of performance and control of the Rolls-Royce arg the inevitable result of this craftsmanship and attention to detail.