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Moulding Tyres to Halve Deformation Stresses

10th April 1942, Page 36
10th April 1942
Page 36
Page 36, 10th April 1942 — Moulding Tyres to Halve Deformation Stresses
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Which of the following most accurately describes the problem?

A Risunid of Patent Specifications that Have Recently Been Published

ARUNNING tyre is" Continually

• being flexed between two states, an unloaded condition in which the cross-section is approximately cular, and a state in Which the crosssection is shortened radially and lengthened in a sideways direction, the latter Occurring wills ground contact is made. Manufactiffers calculate the maximum permissible value of this deflection, and define the air pressure accordingly, but according to patent No. 543,286, a considerable improvement can be effected by modifying the

usual shape. The patentee is Tyresoles, Ltd., Bird Hall Lane, Cheadle Heath, Stockport, Cheshire.

It is proposed to effect the curing operation on the carcass while it is constrained to a shape ril'dway between the two extremes mentioned "above. The effect of this treatment is that during use, instead of the tyre being flexed between zero and full deflection, it is subjected to only half the stress thusrepresented, alternately in plus and minus directions. The load on the cords, therefore, is halved, resulting, it is Claimed, in cooler running and longer life. The patent covers also the processes used in carrying out the invention. • Our group of diagrams comprises a side view, and cross-sections on three

radial lines. On AA the tyre is unloaded and, in accordance with the new scheme, distorted in one direction, on AB it is fully loaded and distorted in the other, whilst on AC it is half loaded and undeformed from the shape to which it is moulded.

SPLIT ROLLER BEARINGS MADE FROM STRIP

I NEXPENSIVE manufacture and widened application are objects cif 'a design for a toner bearing detailed in patent No. 543,180 from C. Ablett, Cooper Roller Bearings Co., Ltd.,

King's Lynn. It is of the diametrically split type so that it can be assembled on a shouldered shaft and does not have to he put on endways.

Inner race, roller cage and4puter ring are all formed in halves, the first-named having bolts for re-uniting the parts. To avoid the formation of a sudden ridge•in the raceways, the inner member is-split helically, the line being virtually on a plane at an Atingle to the axis, whilst the •outer nee is provided with plating V-notches. The design not only permits assembly in places inaccessible

to a one-piece race, but also allows the various parts to be bent from strip. This,, indeed, appears to be the essence of the patent.

In these days of economy in materials, such construction is a considerable improvement upon the usual Method of machining from the bar.

INJECTION TIMING BY AIR AND EXHAUST PRESSURES

A CCGRDING to patent No. 542,872, ritneither the centrifugal nor the suction-operated type of automatic advance gives, in the case of .oil engines, a sufficiently correct variation of injection timing, and an improved method is disclosed in this specifica

tion, Limited to engines employing pressure charging, the scheme comes from A.B. Atlas Diesel, Stockholm, Sweden.

It is proposed to vary the timing in accordance with the pressure of the scavenging-air supply. Advantages claimed are that this pressure varies directly with the engine speed, and that even with a constant engine speed the pressure can he made to vary with the torque by the simple method of opposing it with, the exhaust pressure. The effect of adjusting the timing to suit both of these functions gives a,n early injection for both high-speed' loads and low-speed loads, combined with a late injection for idling, a factor tending fowards smooth running when the engine is ticking over. Referring to the accompanying diagram, there is a spring-loaded piston (3) ,which is subject to the scavenging air pressure via pipe 4 and to the exhaust preSsure via pipe 2. The piston moves a helical-And-straight splined collar (5) on the pump '(1), which adjusts the timing in: the usual manner.

JET NOZZLE FOR PETROLINJECTION ENGINE PETROL engines with ' fuel introduced into the air charge by injection, instead of by forming the gas-air" mixture in a carburetter, may power the commercial motors of the future, hut there is little indication yet of :ally impending entry, on their part, into our industry.

That the matter is receiving:attention, however, in quarters asSociatecl with road transport, is evidenced by patent No. 543,378, from Scintilla, Ltd., Soleure, Switzerland, in which a nozzle for the delivery of petrol, kerosene or gas oil, into the air flowing to the cylinder, is described. .It is stated that the fuel may be supplied under• pressure to the nozzle without interruption, while the engine is running.

The patent does not deal with methods of control.

Main claims, according to the specification, relate to the proportions of the passages and chambers numbered on the accompanying drawing. Passage 1 is preferably 1.5 to 3 times the crosssettion of jet 3, and the diameter of chamber 2, 10 to 15 times that of jet 3. These relative dimensions and the fact that the passage (1) meets the chamber (2) at a tangent have an important bearing on the atomization of the fuel and the shape of the spray.

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Locations: Soleure, Stockport, Stockholm

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