Passing Comments

2nd May 1958, Page 64

2nd May 1958

Page 64

Page 65

Page 64, 2nd May 1958 — Passing Comments

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Internal Spraying of Petrol Tankers

THE table under the heading "Tank Loads and

Materials," published in the Bulk Traffic Handling Number of The Commercial Motor dated March 14, created much interest, but there is one reference in this table which has raised a question. For petroleum spirit it was suggested that the protective lining of mild-steel tanks could be sprayed Epikote or Prodorfilm; for aviation spirit, however, to this was added "spraying with aluminium."

It now seems that the use of aluminium in this way may not prove satisfactory as applied to the conveyance of highly combustible materials. It is just possible that, if rust be present, this iron oxide and the aluminium, in the presence of oxygen, might give an incendive spark, if given a sharp blow, as could conceivably result from dropping a dipstick into an empty tank.

Research associated with this subject has been carried out in connection with safety in mines. It would, therefore, be advisable for readers who are making use of this table to strike out the reference in the table to aluminium spraying for this particular purpose.

Balancing Wheels Electronically •

5OMETHING unusual in wheel balancers has been announced by the Alernite Division of the StewartWarner Corporation, Chicago. It is an electronic type, built especially for goods vehicles, coaches and buses, and it deals with all sizes of wheel without the need for removing them from the .vehicle. Moreover, it will not become obsolete with changes • in the sizes of rims or tyres. It corrects both up and down and side-to-side unbalance

c20 and has a dual-control vibration pick-up which registers at all speeds tremors as small as 0.002 in. Forming part of the equipment is a 5 h.p motor spinner which turns the wheels at the speeds required.

• The balancing of front wheels is particularly important, for not only does it reduce vibration throughout the vehicle, but it can lower maintenance costs 'at the front end, lengthen tyre life, help in obviating driver fatigue and increase safety.

No Visible Means for Support

1HE versatility of air when applied to transport seems to be unlimited. The pneumatic tube and cover were followed by the tubeless tyre and air suspension. Now the Ford Motor Company of Detroit have demonstrated an experimental scooter called the " Glideair." It has no wheels and, instead, is raised a fraction of an inch above the ground by a film of compressed air, approximately 0.0003-in, thick, driven through apertures beneath the "scooter." There is therefore no road friction to overcome.

Present disadvantages are said to be difficulty in steering and restriction to highly polished roads because of the, small clearance. Ford designers hope to overcome these disadvantages and have already built a scale model of a wheel-less car. When powered by a gas turbine or' jet engine, they estimate it could travel at up to 500 m.p.h.

With the wheel close to its maximum speed capabilities, the designers consider wheel-less travel will be a reality well before A.D. 2000.

If that is correct is seems a pity, that so much time was spent by ,the Monopolies Commission in reporting on the supply of pneumatic tyres.

New Method of Weight Reduction

WHERE extreme lightness in certain parts is a major consideration, the familiar balsa wood has been eclipsed by a new moulded product. This is composed of plastics foam resin contained in glass-fibre shells.

In the production of such parts the mould is first waxed to prevent sticking and the glass-fibre shell laid within it. Liquid resin and a catalyst are then poured into the shell. The results are said to be stronger and less costly than the wooden parts which they replace.

More Use for Permanent Magnets

IN many toy electric motors considerable use has been , made of permanent magnets. Now, however, it has been claimed by an American concern that their magnets, known as " Indox," have become a practical possibility for d.c. motors, ranging from fractional to multiple horse powers. It is claimed that the specific advantages of the substitution of permanent magnets for those with wound-field coils are higher efficiency, cooler operation and less use of expensive materials, such as copper. Other qualifications are simplification of construction and economy in manufacture.

I-lot and Cold Plugs

THERE are many people who still have only a vague I conception of what is meant by " hot " or " cold sparking plugs arid their relative advantages or advantages. Actually, there is no connection between the heat range and the intensity of the spark. The hot or cold refers only to the temperature of the insulator at the firing end. A hot plug retains the heat, thus tending to burn away oil and carbon deposits which form when an engine is running under light service conditions.

On the other hand, a cold plug assists in obviating overheating or pre-ignition when the power unit is operating Under heavy loads and at high speeds.

• Even with high-quality fuels, long periods of slow running in city work may cause deposits which will result in shorting and misfiring, although at least one petrol contains a material which will convert a " shorting " deposit into a substance which acts as a non-conductor.

Ribbing the upper part of the insulator of the sparking plug is not done with the object of cooling it, but to provide a longer—and thus more difficult—path for the ht. current, particularly when the plug is wet or dirty.

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