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SCIENCE Supplies the SOLUTION A CHEMICAL treatment has been developed that

15th November 1946
Page 40
Page 43
Page 40, 15th November 1946 — SCIENCE Supplies the SOLUTION A CHEMICAL treatment has been developed that
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ensures a transparent chromate film on parts coated with zinc or cadmium, which, it is claimed, does not tarnish. Parts are treated by immersion in a special solution, after which they can be rinsed in a weak caustic solution to produce a higher lustre, and then dried..

A new nitrocellulose lacquer is said to be the most durable ever manufactured. Apart from durability, an unprecedented depth and lustre characterize the finishes, which are available in more than 200 greys, browns 'and greens. The deep lustre is said to result from the high transparency of the film, and the glowing effect is enhanced by small particles of aluminium flake, reflecting and diffusing the light from within. The majority of the new colour shades are made by using a pigment— ferric hydroxide—not previously used for this purpose. This material is employed in the form of extremely fine particles, which accounts for the high degree of translucency.

Recording •Heavy Oil A new unit renders possible the control, integrating, remote indicating and recording of heavy fuel oil. The device is a combination of a piston and pneumatic-type signal transmitter, and is applicable to other liquids, such as viscous fluids, as well, because its accuracy is not affected by viscosity changes.

In addition to the nickel-iron cobaltaluminium magnets for speedometers, etc., already in existence, the first nonmetallic, non-conducting magnet material ever made has been produced. It is a hardened, sintered combination of iron and cobalt oxides mixed in powder form. The magnets so produced are exceptionally light, and their non-conductive properties preve electrical losses. They also have a high resistance to demagnetizing forces. • Another new magnet material of high intrinsic coercive force is suitable for magnets used in strong electrical fields. It is ductile and malleable, and can be punched, rolled, machined or ground. An air-cooled, 8 to 10 b.h.p. twincylindered engine has been designed for efficient operation in a wide range of temperatures and has proved equally successful at from 10 to 50 degrees C. It is adaptable to use with paraffin, and will work on petrol-oil mixtures as well as on straight petrol. A specially designed carburetter is provided, and adequate cooling fins ensure trouble-free operation at high temperature.

Felt" Rubber A new process makes use of discarded rubber tyres for producing a fibrousbase material which can be called felt rubber. It comprises grinding off the tread and wall parts of the tyre, producing a finely divided form of cured rubber, and then grinding the two products with pine tar. This should be so proportioned as to produce a moist powder, which is then slightly compressed into a layer and cooked in steam at about 170 degrees C. for about four hours under an approximate pressure of 100 lb. per sq. in. The material can be used in many ways.

For cutting apertures in surfaces on objects such as cylinders, tanks, etc., where the sheet cannot be flattened, a new tool has been designed with a base having a clamp and a cutter, which is attached to it by a flexible arm. The cutting member may be placed at any angle to the supporting arm, which is made to rotate about an axis concentric to the base. Operation may be manual or mechanical, and the pressure on the cutting element is readily adjustable.

The latest success in powder metallurgy is the production of cemented steels by compressing the particles until they form a porous compact, and then infiltrating a molten copper alloy, the cementing agent, by capillary action. The compact is placed in contact with the copper alloy, and heated in a furnace to just above the melting point of the alloy. This is usually done during the sintering operation required to strengthen parts shaped from the pressed iron or steel powder.

These materials are said to render possible the production of dense, strong metals from low-cost materials at comparatively low pressures. The parts retain the characteristics of both the copper and the parent metal, permitting direct brazing on to other metals without a brazing alloy, facilitating plating, retarding corrosion, and providing bearing qualities for gears and cams. Acid will dissolve copper from the face of the part to any desired depth, and the porous surface will retain lubricant. Special alloys for infiltration, where exceptional strength or wear resistance is required, are in prospect.

Experiments have been carried out in which powdered and pressed stainless steel has been infiltrated with copper and silver. The surfaces obtained by the cementing process resemble those of die castings. If special smoothness be required, later finishing may be needed. The production is most applicable to parts weighing up to 20 lb.

An important advance in the direction of solving excessive piston-ring and cylinder wear is the application of porous chromium. Best results appear to be obtained with a porous chromium in the top groove, and cast-iron rings in the others.

Colour is being given to aluminium by first 'treating it in a special electrochemical bath, then dipping it into a dye. The process increases the decorative uses of aluminium. [This anodizing method has been used for many years.—En.] For sealing small breaks and nail holes in tyres, a new rivet consists of a circular rubber base, and a rubber stem with spiralled steel needle. The stem is first lubricated with rubber cement, the needle pushed through the Me from the• inside and then pulled off. In service the stem shOrtens and spreads against the walls of the hole.

Heating and Ventilating In a new system of heating and ventilating lorry cabs, fresh air is drawn through a weatherproof opening in the cab side panel, heated by a hot water radiator, and then forced by a fan into a plenum chamber formed by sealing off the space behind the instrument panel. Adjustable 'openings in the chamber direct the air up over the windscreen for defrosting, or forward into the cab as desired.

Some experimenfal work has been carried out by American magnesium producers on the application of magnesium to road transport. Satisfactory road trailers, which need a large volume capacity for small mass load have been made and used with excellent results. The importance of non-paying load cannot be overlooked by road transport designers, and in this field magnesium alloys should serve a useful purpose.

The process of producing pistons from pressings has, for some years, been developed in both the United States and Germany, and, latterly, in England, the deep-pressing technique has been considerably developed. Experiencz gained in this country with pressed pistons has been applied to heavy-duty oil engines in Which, although the duties are different, the combined mechanical and thermal stresses do compare, and sometimes exceed the combined stresses to which ordinary engine pistons are subjected.

The most suitable material for pistons is aluminium, which has a low specific gravity, and which, when alloyed with such elements as copper, nickel, magnesium_ silicon, etc., gives a material of suitable properties. The strongest known piston material is Y alloy, whilst a 12 per cent. siliconaluminium alloy has a slightly lower coefficient of thermal expansion and has comparatively high hot strength values. To meet the higher mechanical and thermal stresses, hydraulic pressing is undoubtedly a distinct step in the right direction, and when conditions of service are equal, the process gives increased piston life.

New Permanent-magnet Alloy

Sheffield has produced a new permanent-magnet alloy known as Alcornax 11, which has the highest energy value of any magnet alloy commercially available. A new plastic has been developed which, it is claimed, has a greater toughness or high impact strength than any other cellulose ester. Cellulose propionate, from which it is made, has been a laboratory plastic for many years, but only recently has a method of producing propionic acid, from natural gases in commercial quantities and at reasonable prices, been developed. Present produetion is on a pilot plant scale, but it is anticipated that large-scale production will begin in 1947. It is colourless, can be printed and lacquered without fear of tackiness and takes any colour, or can be produced mottled or with intricate designs. The specific gravity is said to he about 1.2 or less. It is suggested that it may make a very good material for steering wheels.

Passenger-bus tyre carcases are being made at the rate of one every two minutes without skilled labour by a semi-automatic machine. The tyre is built around a rotating cylinder, the tread material being dropped into position from overhead rolls. The only manual operations consist of placing the beads into position, cutting the breaker strip, and removing the tyre. Production is five times that achieved by hand, and twice that of other machines.

Sufficient advantages in performance and economy are expected from the application of petrol injection to bus and truck engines to outweigh, by far, the high first cost. This system permits of the use of large intake manifolds, and gives the designer a free hand with intake and exhaust valve timing. 'especially important with supercharging. There can be extensive overlap in the valve timing and this promotes good scavenging, whilst evading backfiring and loss of fuel, as well as reducing erratic idling. If fuel be admitted early in the intake stroke, much of it can be evaporated before the intake is completed. This cools the residual gases and the fresh-air charge, thus the pressure in the cylinder is decreased, so that a greater volume of mixture is drawn in. Moreover, the incoming air can be cold. which means greater weight per unit volume.

Injection also allows of equal fuel distribution to the cylinders, gives quicker response to the throttle, improves cold starting, reduces the risk of fire, utilizes lower grade fuels, shuts off automatically in deceleration, and is free from altitude effects. Apart from the first cost, injection has the disadvantages of being more complicated, causing higher maintenance cost, and being most suitable for engines designed for it.

Cylinder blocks are to be machined with the continuous process, in which each block is carried automatically from machine to machine. Such processes call for high production, but offer important man-hour economies. Tyre changing and track checking are easy on a new vehicle by jacks that raise the wheels off the ground. The rear jack is a tubular frame connected to an hydraulic three-link hitch. The forward end of the frame is fitted with U-shaped yokes that cradle the axle.

Tyre Changing Made Easy

When power is applied, the frame is pulled backward to raise he rear treads 4 ins. The front end jack is-a smaller frame, one end being placed under the axle, the other against the ground. It is hauled to a lifting position by a chain which is hooked to the rear unit for the lift.

Two colours of special baking enamels are sprayed at one and the same time with a new spray gun. The idea is to achieve new finishing effects in a single operation, such as simulated hammer finishes and spatter effects. This gun differs from the one-colour types principally in having two inlethose connections.

Synthetic rubber tyres have been improved to the point where they outwear the pre-war product made of natural rubber, it is claimed. A wider tread and flatter profile, together with the use of OR-S 10 material, have

proved successful in this respect. In this material, a resin-base soap, rather than a fatty acid soap, is used as an emulsifying agent in the latex.

Among the new features of the latest passenger vehicles are portholes at thc eye level of those who stand, and thermostatically controlled fans exhausting air through roof louvres. The vehicle is equipped with glass that filters out 60 per cent, of the sun's heat, and a wide-vision windscreen, placed at a sharp angle, reduces glare.

A spherical self-aligning bearing consists of a hard chromium-plated steel ball with a hole for a shaft through its centre, and a one-piece bronze outer race press-formed around the ball. As the bail projects beyond the race, misalignment to c. considerable extent causes no trouble.

Extra Power on Hills

The use of an auxiliary engine in a bus, to supply extra power for acceleration and hill-climbing, is under consideration. Two types of installation are being tried out. One contemplates a main engine for ordinary service, with a smaller auxiliary engine which will cut in automatically when the demand exceeds the capacity of the main engine. The other employs two engines of equal size.

Designed particularly for heavy offthe-road tracking, a new wire-cored tyre is said to be virtually blow-out proof, and to increase tread mileage by 25 per cent. Thinner walls, the result of fewer plies, help towards cool running. Crankshafts (particularly for heavy use), gudgeon and other pins, in which distortion causes trouble, are being made from nitrided steels. Nitrided .austenitic steels have been used for sleeve valves and poppet valves. Nitrided cast irons, containing aluminium and chromium, are being employed for cylinder liners.

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Locations: Sheffield

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