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The Proving of "Con-Rods."

23rd May 1912, Page 13
23rd May 1912
Page 13
Page 13, 23rd May 1912 — The Proving of "Con-Rods."
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Much of the undoubted efficiency of the modern high-speed internal-combustion engine is due to that branch of the development of design which has dealt with the careful balancing of parts. This was a problem which in the early days of the evolution of the petrol engine received scanty attention, and many of the earlier engines were woefully lacking in both static and dynamic balance.

Realizing the degree of accuracy which is required nowadays by manufacturers of such engines in the matter of balance, W. and T. Avery, Ltd.—a company which, of course, has a world-wide .reputation as a maker of weighing machines and other accurate testing apparatus, has devised an interesting little apparatus which is intended to enable the manufacturer to secure absolute uniformity in the matter of connecting rods. The balancing of the rod itself is always a matter for skilful calculation, as, of course, it is a component of which the movement of part of the mass is rotatory, whilst the rest, that towards the small end, has a somewhat complicated reciprocatory movement.

We reproduce a photograph of this new little apparatus herewith. It is intended, by this device, to ascertain during the progress of manufacture, the exact position of the centre of gravity of each connecting rod on its longitudinal axis. This renders it possible to ensure that each rod shall be uniform and consonant with a standard. The method of using the machine is as follows. A standard connecting rod of approved construction, which has been finished to a high degree of accuracy, is suspended by means of knife-edged mandrils from the beam and frame. These can be seen in the illustration. The adjustable poise weights are then set and screwed at the position of equipoise to the beam or lever, after the crank end of the connecting rod has been suspended therefrom. The pin end of the rod has to be longitudinally adjusted by means of a nut and screw in order to obtain the vertical suspension of the connecting-rod ends. The standard connecting rod is then removed from the machine, and the mandrils are withdrawn.

Other connecting rods of the same type wh:ch it may be desired to prove by the standard then have the mandrils inserted in their bearings, and these

rods can then in turn be suspended from the beam and frame, as previously described, and, if the .position of the equipoise of the beam be attained, the connecting rods are automatically certified as correct. Should the beam, however, not be counterbalanced with the settings which have been previously determined, the connecting rod should be removed and altered with regard to its weight by machining or filing, until the beam. or lever is brought into equilibrium, thereby ensuring that the centre of gravity of all the connecting rods, on their longitudinal axes, are standardized and verified.

We do not hesitate to state that this interesting little machine is a valuable adjunct to the equipment of the viewing room. The extent to which the efficiency of running modern high-speed engines depends upon the accurate balancing of rods and pistons, as Well as the more easily regulated crankshaft, is undisputed. Avery's connecting-rod tester would soon pay for its keep.

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