Passing Comments
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David Brown Develops PREE-CUTTING stainless. Easily Machined StainA steel castings have been
less Castings. . . introduced by the David Brown Foundries Company. Measures which were successful in improving the machining characteristics of wrought, corrosionresisting steels have been extended to cast types without reducing, to any marked extent, their mechanical and other special properties. They will no doubt he welcomed by production engineers who have previously had to face difficult machine-shop problems presented by highly alloyed steel castings.
Adjusting the Octane THERE is always something Number to the Engine L fresh in connection with Needs motor vehicles and their power units.. As an example of this, we may refer to experiments carried out by Thompson Products Inc. and the Thompson Vita-Meter Corporation of America. They point out that the anti-knock qualities of fuel, i.e., the octane numbers, are based on the operation of engines at full throttle. Consequently, at times when an engine is not required to give its full power the anti-knock quality is wasted. It was therefore decided to find some way of introducing an antidetonant, or mixture, of these, as and.when required,' thtA varying the octane number to suit the engine. In aircraft engines alcohol-water solutions are fed in with the petrol when unusually high outputs are required, as when supercharging. To cope with motor-vehicle engines, a device called a Vita-Meter was produced. This is, in effect, a special carburetter which supplies such a solution as alcohol-water
tetraethyl lead only when necessary. Thus, there is a great saving in the amount of lead employed, and it is rapidly ejected. It is proposed to use this apparatus with a good, straight-run petrol, but if fuel with a high octane number be employed this can also be stepped up by the injection process to meet the future needs of engines having a specially high compression. The increase in the octane number can be up to 30. It is claimed that there is a considerable reduction of sludge, increased life of valves and sparking plugs, lower oil consumption, less engine wear and greater power.
Should Cylinder Glaze IN the old days an operator be Removed when with any claims to technical Overhauling ? . . . qualifications would. admire
the beautiful glaze often developed on cylinder walls. It now seems, however, that he was wrong in considering this glaze to be an advantage, at least when overhauling a power unit, and particularly when fitting new rings. In a recent analysis of opinions by American maintenance engineers and piston-ring manufacturers, the majority expressed the definite view that glaze should be removed in order to obtain the best seating between new rings and cylinders. At the same time, it was pointed out that the success of re-honing or glaze removal depended very much upon really adequate cleaning, even so far as washing the cylinders in petrol followed by soap and water. Any failure to remove abrasive matter may result in the mating period becoming a wearing-out process. It would be interesting to know what our maintenance engineers think of these suggestions.
THE jointing racket has returned, and this month one of our readers in the Birmingham area has become a victim of it. Some weeks ago a man canto his office and after some sales talk an order was signed for six sheets, the caller saying "You won't want much, just two each of 1/32 in. and one each of 3/32 in. at 7s. 9d per lb" Our friend thought that the total would not be more than £6, but when the bill came it was for over £32. years ago, when the racket started, the general scheme was for the salesman to tackle some small official and boost him into signing the order, for which the firm concerned usually had to accept responsibility. Little or nothing can be done once an order has been signed. The racket lies in persuading the buyer that he is obtaining only a small quantity instead of sufficient to last him for, probably, many years_
Beware of Mow You Buy jointing in Large Sheets
Magnetic Drive for A NOVELTY in connection Fans and Other I—I` with the driving of such
Accessories parts as engine-cooling fans, dynamos, compressors, etc., has been developed by the Eaton Manufacturing Co. of Detroit. It is referred to as the "dynamic drive" and involves, no mechanical connection, use -being made, instead, of a rotor with an electromagnet working in a soft-iron drum. When current is applied to the rotor the magnetic lines of force cause the drum to revolve, thus providing an interesting method of control. For example, the cooling fan can be brought into operation only when the enginettemperature reaches a certain height, a thermostat cutting off the current as the water coots. In a similar way, the dynamo drive can be virtually disconnected if the battery be well charged, whilst fans for heaters can be, brought into action at predetermined temperatures.