Continued Progress With Automobile Research
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One of the Most Useful and Valuable Sections of the Work Performed by the Institution of Automobile Engineers is that dealt with by he Automobile Research Committee at Its Well
equipped Laboratories
AVISIT to the Research Department of the I.A.E., which is under the aegis of the Automobile Research Committee, of which Mr. J. Shearman, president of that Institution, is the chairman, is always of great interest, both from the point of view of the work being carried on and of the people whom one meets. Apart from that, au excellent tea is provided by the Firestone Tfre and Rubber Co:, Ltd., at its athletic club, which is almost opposite the premises
of the Research Department. The latter facilifY, of course, applies only to special occasions, such as the annual inspection.
The services of the Committee are divided into two main sections— information and research. The former consists mainly of the preparatibn and distribution of current British and foreign technical literature likely -.to he of interest to the many concerns affiliated to this Department.. There is also an .excellent library containing many, technical books and files of periodicals cowering all the subjects pertaining to the automobile industry and its ramifications, research reports,
etc. .
Assisting the War Effort The general research programme is decided by the Research Sub-committee. which, during the war, has been expanded• to include representatives of Government Departments. The problems under investigation have been chosen as being of immediate importance: at the same time, much of the work being performed is of permanent value arid forms part of longrange investigations on fundamental problems. A considerable amount of confidential work is also being carried out for Government Departments.
Now,, as regards the research side, we will commence with the chemical laboratory. Two rooms in this contain equipment for the analysis of materials, samples of exhaust gas, and for the chemical and physical examination of
'fuels and lubricants. .... . One interesting activity is the determination of the size of inorganic particles contained in used oil. Great difficulty has been experienced in the endeavour to -separate this material from the carbonaceous matter present, and the method adopted is repeated centrifuging in solutions of suitable specific gravity.
Akin to this is the microscopical examination of abrasives in connection with the harm they may do to bearings. Tests are conducted with artificially contaminated oil , containing various powdered substances, of which the particle size is determined. The results obtained show the great harm which " gritty " oil can do.
As part of the general investigation On oil cleaning. many examinations of samples of used oil from the sumps of oil and petrol-engined vehicles are being conducted.
What was formerly the chassis laboratory is at present being converted into one for materials testing and the study of metallurgical problems. In this connection, a 50-ton Denison universal testing machine has just been installed. Other equipment to be included will be Vickers and Firth hardness testing machines, WahIer fatigue-testing machines and a Vickers projection microscope.
One room is being arranged for measuring. This will contain a Hilger inspection enlarger,. a Tomlinson surface-finish recorder, Sykes gear-profile measuring machines, etc. The Tomlinson device, which was on show, draws an enlarged record of the surface finish by means of a diamond-pointed stylus, which is drawn slowly over the surface. This, by means of a system of levers; provides a high magnification of the movement perpendicular to the surface. The record is drawn on a smoked-glass plate, which is then photographed through an enlarger. Records of the surface finish of gear teeth and of valve rockers were. on view.
• Much work has been devoted to an endeavour to solve the problems involved in the conversion of petrol and oil engines to use producer gas as their fuel. This is now in its concluding stages. During this work several interesting forms of gas mixer have been developed, particularly to meet the requirements of oil engines for road vehicles when Operating on producer gas with a pilot injection of oil for ignition purposes.
Other tests include those for oil filters, the durability and wear of engine bearings, also those of the bush type, the fatigue strength of crankshafts, and the durability of gears. One point of interest in dmnection with the last named is the use of two machines to test the effect of various metallic platings in connection with the surface failure of gear teeth.
Use of Electronic Gauges As regards engine bearings, a machine has been developed by which a fluctuating load is applied to a bearing by means of an eccentric and flexible lever. The test shaft being rotated by motor, through the medium of a chain drive, the .load fluctuations can be synchronized with the rmoiu tions of the shaft. Fluctuations of load and of torque are measured by electronic strain gauges.
In certain cases cathode-ray °scalpgraphs are connected to the strain gauges to give visible indication of the cyclic variations of load. These strain gauges, which are of both the resistance and capacity types, constitute one of the most interesting developments in measuring bending moments, torsion, etc., and a brief description of one of the resistance type may not be out of place.
To make it, a large number of turns of very fine rhsistance wire is wound around a paper former mounted on a mandrel. The mandrel is then withdrawn, and the former with its coil flattened. The ends of the resistance are connected to terminal wires, and the resulting component is mounted between two pieces of fine insulating paper.
Resistance Slips Glued On These " slips " are carefully glued to the surface of a shaft or tube wherever it is desired to indicate or measure the strain. They can be curved around a. bar or tube, mounted longitudinally, or set at an angle, particularly where it is required to record torsional strains. The principle involved is that the resistance of a wire is increased or decreased according to the degree of strain upon it, and with a large number of turns the effect is multiplied accordingly.
The neat -little demonstration equipment designed to show the employment of, and the effects obtained with, these resistance-type gauges was almost
fascinating. A slight pressure on a most solid-looking bar, or the comparatively weak turning of a handle connected to a tube secured at the other end only, was sufficient to move an indicating light arrow a considerable distance over the dial of the visual recorder. We watched these gauges in actual use in . connection with the fatigue testing of a large cast-iron crankshaft, and found most instructive the constantly changing light diagrams shown on the oscillograph.
A capacity-type unit is used on the bearing-testing machine, for measuring the fluctuating load on the bearing by means of the strain in the connecting rod. Another exhibit of this nature was the capacity-type electric torsionmeter designed to measure fluctuating torque.
It will thus be seen that the department is most up to date in its methods and equipment.