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).
Technical review of the Bentley Mark V chassis, along with articles on plastic bodies and a new magnetic alloy.
| Identifier | ExFiles\Box 160\5\ scan0330 | |
| Date | 1st May 1941 | |
| 152 AUTOMOBILE ENGINEER THE BENTLEY MARK V CHASSIS (Continued) Occupying the centre of the frame is a massive cruciform cross-member extending from the dashboard to the rear axle, as shown in Fig. 2. It is built up of two long channel-sectioned members, riveted to the side-members and joined at the centre by two plates also riveted on, forming a tunnel through which passes the propeller-shaft. A fourth cross-member of channel section is arranged behind the rear axle and just in front of the petrol tank. Behind this member the side-members are reinforced by additional channel-sectioned pressings riveted on to form a box section. The length of the chassis over bumpers is 15ft. 11in., while the overall width is 5ft. 9in. The wheelbase is 10ft. 4in., the track 4ft. 8in. in front and 4ft. 10in. at the rear. The ground clearance is 6½in., and the turning circle is about 42ft. PLASTIC BODIES Interesting Developments by the Ford Motor Co. IT is reported that Henry Ford has stated that some time this year he will have an automobile the entire superstructure of which will be made of plastic except the welded tubular steel frame of the body. The plastic, composed of 70 per cent. cellular fibres and 30 per cent. resin binder, and moulded under heat and pressure, is, he said, superior to steel in all properties save tensile strength. It is half as strong in tension and has ten times the resistance to impact without denting as automobile body steel. Mr. Ford demonstrated the claim by swinging the blade of an axe with all his strength against an automobile door panel made of plastic without affecting the appearance. A similar blow on a door panel of steel cut through the metal, bent the edges of the cut and indented a large area of the surface. Although mud fenders made of the plastic are breakable, the ductility is so low that they are not crumpled or dented by those minor collisions that account for so many damaged steel fenders. The rigidity and impact resistance of the body structure will be an important safety factor in the new car, which will be lighter and more economical to operate than present all-steel cars. Research men in the Ford plastics laboratory have been working for ten years on the development of industrial uses for farm products, which is one of Mr. Ford’s particular interests. The experimental work is in charge of Robert A.{Mr Adams} Boyer, a young research chemist, who has twenty-eight assistants. Body panel plastics Of most interest and importance is the development of body-panel plastics, for which the company has a number of formulae. Having developed various plastics for many non-structural extruded, moulded and injected parts of the automobile, attention is now centred on producing panels that will form an integrated part of the car structure. A complete set of dies was being made at the beginning of this year to be used in pressing panels and other parts of bodies for the first road-test models. Mr. Boyer states that the best plastic sheets weigh only half as much as corresponding steel sheets. A problem on the solution of which the chemists are reported to be making good progress is the incorporation in the plastic of suitable colours at low cost. When this is accomplished there never will be any need to refinish the plastic bodies to restore the colour. A high percentage of resin was needed in earlier plastics to enable them to be drawn and formed between dies in a press, and this made the sheets more expensive than steel sheets. This requirement for a high resin content has been overcome by the laboratory development of a pre-forming process. The fibrous materials suspended in a liquid which is passed through screens of the approximate shape of the panels, fenders and others parts to be produced. The fibres deposited on the screens are then saturated with a low-cost soya bean resin binder and finally the semi-formed part is pressed in hot finishing dies. Plastic seats for the new Ford farm tractors are made by this method. The particular fibres used in the plastic for car bodies are not disclosed, but the cellulose portion of a typical experimental plastic consists of 50 per cent. southern slash pine fibre, 30 per cent. straw, 10 per cent. hemp and 10 per cent. ramie—this last the fibre of an Egyptian plant that grows well in many parts of America. Larger proportions of ramie increase the tensile strength of the soya bean plastics, which is about one-half that of mild steel. On the basis of 1,000,000 cars a year with plastic bodies, Mr. Ford said the Company would consume at least 170,000 tons of agricultural products and 50,000 tons of synthetic chemicals. The necessary materials would include 100,000 bales of cotton, 500,000 bushels of wheat, 700,000 bushels of soya beans and 500,000 bushels of corn (maize). The wheat, corn and beans are interchangeable (as a source of binder resin). Smaller quantities would be needed also of flax, pitch pine, sugar-cane, alcohol, cork, rubber, tung oil, lard, glue and hides. Nearly 280 lb. of farm produce now go into every Ford car, and 200 lb. more will do so when plastic is substituted for sheet steel, but the car will be 300 lb. lighter. The company’s plastic moulding plant now uses 21,375 tons of soya beans per year. Synthetic wool A synthetic wool which seems to have great possibilities has been produced in the Ford laboratory from soya beans, 57,665,000 bushels of which were grown on 7,789,000 acres in the United States in 1938. This soya bean wool is the only protein fibre that has yet been made from vegetable matter, all others being of animal origin. By a proved method of chemical and mechanical processing, it can be produced in industrial quantities much cheaper than sheep’s wool and with the fibres always of the same kind and quality. It can be used in upholstery or matted with rubber to make springs, durable padding for motor cars, bus and truck seats. Instead of reducing the demand for natural wool, the synthetic wool would increase it, for the two must be used together in fabrics, as exemplified by a suit of clothes, woven of 75 per cent. sheep’s wool and 25 per cent. soya bean wool, which is owned and highly prized by Mr. Ford. The lower cost of fabrics made of a mixture of the natural and artificial fibres would extend their use widely where pure animal wool is too expensive. Keen interest is felt in Detroit automobile manufacturing circles in the progress toward plastic bodies, particularly in view of the possibility of a steel shortage and high prices if the European and Asiatic wars continue for two or three years. Commenting on this, George W. Walker, an industrial designer and stylist of a prominent make of car and many automobile appointments made of plastics, said that plastics can make a distinct contribution to the cause of national defence by enabling the steel industry, now operating at capacity, to devote more and more of its output to urgently needed war materials. Shatterproof windscreens and windows He mentioned the opportunity for improvement in cars that plastics will make possible. Curved windscreens and windows of transparent, shatterproof plastic, in limited choice of colours and shades, are the material itself, which can need no rust and will not fade or have colour rubbed off by cleaning and polishing. There may be moulded clear sunshine tops that admit health-promoting ultra-violet rays and exclude hot infra-red rays, and immunity to shocks that dent and crumple fender and body steel, ruining the appearance of so many cars. A NEW MAGNETIC ALLOY AT a recent meeting of the American Physical Society, reported in The Engineer, Vol. 170, No. 4,423, E.{Mr Elliott - Chief Engineer} A.{Mr Adams} Nesbitt and G.{Mr Griffiths - Chief Accountant / Mr Gnapp} A.{Mr Adams} Kelsall, of Bell Telephone Laboratories, New York, N.Y., introduced a magnetic alloy possessing remarkable qualities. It will be known as “Vicalloy,” because its contents are vanadium, iron and cobalt, the percentages varying from 6 to 16 per cent. vanadium, 30 to 52 per cent. iron, and 36 to 62 per cent. cobalt. After melting, it is cast into an ingot, which is hot swaged to ¼in. diameter. It is then drawn into wire or rolled into tape as desired. When in final form, it is heat-treated to develop its magnetic qualities.—Air Ministry Abst. 84/24. (948) MAY, 1941 AUTOMOBILE ENGINEER 145 Fig. 4. Near side of engine, showing grouped accessories. of five gears were used, three only are now employed to drive the camshaft, which runs in seven bearings. Constant acceleration cams are employed, unchanged from the previous model. At the extreme front end of the camshaft a small coil spring is fitted. Its function is to keep the camshaft thrust always in one direction to prevent noise. Overhead valves are employed, operated by push rods and totally enclosed rockers, and the tappets take the usual cylindrical form and operate direct in the crankcase. They have a semi-spherical recess in the base to take the bottom end of the push rod. At its upper end the push rods are enlarged to accommodate a semi-spherical bearing for a similarly shaped stud in the end of the rocker arm. A square end and locknut provides for adjustment. Tulip-shape valves are fitted, the exhaust valves being faced with Stellite, and it is stated that they will run for 100,000 miles without regrinding. An interesting feature in the valve guides is that they have glands at the upper end, formed in the lower washer retaining the single coil spring. Inserted valve seats are not employed. Particular interest attaches to the shape of the combustion chambers in the cast-iron cylinder head. It may be described as an elongated lozenge, that is, semi-circular at each end with straight sides. Its greatest width is slightly larger than the cylinder bore but in cross-section considerably narrower. At its base the chamber slightly narrows where it merges into the cylinder bore and the top of the piston is formed with a lozenge-shaped top about ¼in. deep, exactly fitting the neck of the combustion chamber, but with a small clearance space all round. At the top of the stroke a certain amount of the mixture is trapped against the flat portion of the head and travels at high velocity through the space between piston crown and combustion chamber neck, setting up considerable turbulence. As shown in Fig. 4, most of the driven accessories are arranged on the near side of the engine. Gears drive the distributor, on the casing of which are mounted the oil relief valves. Close up to the distributor is the lighting dynamo, the drive being continued through a light shaft having a universal joint at each end to the centrifugal water pump. Carburation Two special type S.U. carburettors are fitted as standard, one of which embodies the S.U. thermostatically controlled starting device. No hand control for the mixture strength is provided. Fuel is supplied to the carburettor by a specially modified S.U. dual electric pump from a 19-gallon tank at the rear of the chassis. As shown in Fig. 7, the pump is mounted on the off side of the frame between the arms of the cruciform frame member. A green warning lamp lights up when the supply is down to about two gallons. There is, of course, an electric fuel gauge on the instrument board indicating the total quantity of fuel in the tank. To enable both halves of the dual fuel pump to be checked separately, a change-over switch is arranged on the instrument board in addition to the ordinary ignition switch which is marked “both,” and which also controls the pumps. The other two positions, marked “A” and “B,” should occasionally be used for a few miles’ running when it each half of the pump is in working order it should make no difference to the running of moderate throttle openings. The S.U. starting device is now quite well known, and the controlling element is a thermostat, exposed to the engine cooling water. This actuates a switch that controls a solenoid, which in turn opens up or closes off the starting carburettor. On starting up from cold, as soon as the water in the engine reaches the predetermined temperature the thermostat opens the switch, re-energises the solenoid and puts the starting carburettor out of action. The starting carburettor is embodied as part of one of the main carburettors. A very large intake air silencer and cleaner for the carburettors is fitted above the cylinder block. This is connected by a large T-shaped member to the two carburettors, which are positioned between the head of the T and the induction system. This is a straight tubular member with six short outlet pipes. At the two junctions between the manifold and Fig. 5. Off side of engine, showing induction system and two coils. | ||