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Passing Comments
Page 64
Page 65
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Carrying the Torch Farther
ANEW principle has been adopted in the Linde Plamsa Torch for arc welding. In this the arc column is confined within a small-diameter tube through which pass both a part of the arc and a flow of gas. By making the nozzle smaller than with a normal unconfined arc, the latter fills a substantial part of it so that much of the gas flow must also be through the arc.
The advantages are said to be flame stability, concentration of power—which is particularly important in metal cutting—and concentration of the ability to accelerate metal particles for coating or blowing molten metal from the cut. Material passed around the arc is heated only a little compared with that passed through the arc, consequently the nozzle is kept comparatively .cool.
Any gas or mixture of gases which does not attack the tungsten cathode may be used, these including the rare gases, argon and helium, plus nitrogen and hydrogen. The power range can vary from a few watts, for welding thin metals, up to several megawatts.
Now a Transistorized Coil
-" RIEF details of a transistorized system of ignition for
petrol vehicles, which is being tried out by the Electric Auto-Lite Co. of America, were given in The Commercial Motor dated December 19, 1958. More recently they seem to have concentrated on a special device known as the Transicoil, which replaces the conventional type of coil and makes a unit little larger than this which can be installed in any battery-ignition installation in a few minutes. It transforms the equipment into a high-voltage, transistorized ignition system which is said to be completely compatible with the other normal electrical components and practically maintenance-free, whilst eliminating condensers.
The distributor contacts work in a normal manner, except that they carry a much reduced current, but through the action of the transistor, set up what is termed a chain reaction and give increased voltage at the sparking plugs.
This new coil will be in production in America in about five months.
c26
More Synthetic Rubber
ESTS with tyres are said to indicate that a new 1 synthetic rubber, Diene, developed as a rubber " extender " by the Firestone Tyre and Rubber Co. of America, can be used to replace a substantial portion of the natural rubber in tyres for commercial vehicles. It is said also that this results in improving to a marked degree the crack resistance, reduces running temperatures and adds considerably to skid-resistance as a result of the new material's pliability at low temperatures. In fact, when blended with natural rubber the temperature rise is comparable with that of tyres made entirely with natural rubber.
Diene is made with butadeine as the base material, using lithium metal derivatives as a catalyst, similar to those employed in the Coral rubber system—also developed several years ago by Firestone—which is similar to natural rubber, and is made with isoprene as the base. The Diene rubber thus obtained is substantially different in polymer structure from that produced with catalysts of the Ziegler or modified Ziegler type. It seems, however, that rubbers prepared from butadeine by the various catalyst systems give approximately the same performance when blended with natural Hevea rubber and used in tyres or other rubber products.
The system and catalyst chosen by Firestone make the new rubber readily adaptable to the 500-ga1, reactors in the Coral pilot plant. The hysteresis of Diene appears to be intermediate between natural rubber and GR-S.
A Million Miles on Gas
RECENTLY a ship laden with liquefied gas arrived at a British port. Although it seems that the cargo was not intended as fuel for motor vehicles, it does open up some interesting possibilities. Many vehicles in America make use of liquefied petroleum gas, which appears to be even more satisfactory than petrol. In this connection Transport Topics, the national newspaper of the motor freight carriers, as road hauliers are termed in the U.S.A., refers to a report from the National LP-Gas Council of
hicago describing how an articulated tanker using this lel had run more than a million miles without a major verhaul and was still going strong. It was actually trrying the same liquefied gas as it used as fuel.
The vehicle was an Autocar with a Hall-Scott Model 48 tgine, and was put into service in October, 1952. About )0,000 miles were run in a mountainous area, always ith heavy loads as its average cargo was 7,650 gal. In idition, the engine worked 3,564 hours in powering the amp for unloading. It is added, however, that just over 1.000 was spent on maintenance during the period.
:ngine and Transmission Additives
70R some 20 years the Slip group of companies has been developing specialized lubrication techniques, and (ports a wide range of industrial and other products to 5 countries, in many of which wholly owned subsidiaries .e maintained. Now Slip Products and Engineering Co., td., 34 Gt. St. Helen's, London, E.C.2, have announced their latest product a lubricating-oil supplement, based .1 molybdenum disulphide, which they have named lot yslip.
"the basic material, which has become well known in the field of lubrication, is not a synthetic material, but is extracted from the mineral, molybdenite, found chiefly in Colorado, and for lubrication its purity must not be less than 98.5 per cent. It is claimed that Molyslip embodies 20 per cent, of this material in colloidal form. It will be marketed in two forms, the ordinary for supplementing engine oil, and Molyslip G for the transmission and steering box.
A simple explanation of how the basic lubricant works is as follows: The tiny, flaky particles are so thin that 40 together will give a thickness of about a millionth of an inch. The sulphur atoms have a strong affinity for metals. but the bond between them is weak, so that whilst the lowest flakes bind themselves to the surface, the upper ones slide freely. It is said that the material actually plates the surface of metals with a film which becomes stronger than the metal, and the material remains stable at high and low temperatures. The main problem, however, is to disperse it uniformly throughout the lubricant, and it is said for Molyslip that it rcmains evenly distributed at all times.
The retail price for a 10-oz. tin of either type is 15s., and in engines it must be used at every second oil change.