THE NEW TORQUE CONVERTER: HOW IT WORKS.
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A Further Attempt to Explain an Invention Based Upon the Application of Obscure Mechanical Principles.
WE HAVE followed up our article upon Mr. Constantinesco's torque converter, which appeared in the issue of The Commercial Motor for October 9th, by an interview with the inventor, and from him have obtained more detailed information concerning the somewhatobscure principles upon which the invention is based. It is not very easy to provide the simple analogies which are so useful in making clear the workings of a piece of mechanism, and thus we endeavoured in our last issue to supplement the diagram provided by the inventor with one which shOwed the power being transmitted through the pendulum. Once the idea of driving through the pendulum is grasped and the idea of allowing the pendulum to by-pass the power is dismissed, a clearer conception of the way in which the device acts can be obtained.
A very simple way of studying the action of the converter is to take a walking-stick with a heavy knob and to ask someone to hold it as shown in Fig. 1, suspending it from its tip with the knob downwards, using the thumb and finger as a pivot. Now take hold of the stick lightly, as shown, and swing it gently_as indicated by the dotted lines. Providing that the rate at which it is swung is not excessive there will be no appreciable pressure experienced in the hand forming the pivot. But now gradually increase the rate at which you are swinging the stick. As the rate is increased, a backward and forward pressure will be experienced in the hand holding the tip of the stick, until at last it will be found ths.t, instead of the .stick swinging from its tip as a pivot, the hand holding the tip will no longer be able to resist the• oscillations, and will yield to the pressure of the other person's hand, and that the stick will be swinging from the knob as a pivot, as shown in Fig. 2. Iu other words, the fulcrum has receded.
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It must not be imagined that the pivot point changes suddenly from one end of the stick to the other; it gradually moves from tip to knob, according to the rate at which it is swung. We will now imagine that the hand is replaced by a connecting rod from a crank; and that the hand forming the pivot is replaced by a pair of links leading to levers with ratchet pawls attached (Fig. 3), and we have a fair idea of the principles governing the invention, shown in a very elementary way.
The example shown in Fig. 1, where the stick swings at its natural speed and causes no movement to the pivot, is what happens when the engine is running slowly, and if Fig: 3 is referred to it will be seen that the weighted lever, or the part which answers to the stick, can, on low power output, swing without imparting any movement to the rear axle through the ratchets. At the other extreme, should the resistance to rotary motion in the rear axle not be in excess of the torque exerted by the prime mover, or engine, a maximum speed would be obtained in the rear axle.
These examples show the two extremes of the system—namely, the engine running light (analogous to the gear being in neutral), and what corresponds to top gear. We now come to the more subtle matter of the method by which the ratio of prime mover and rear axle automatically varies according to the resistance offered to movement of the latter. Supposing that the resistance offered to rotation is very great, as in the case of a car standing still on a very steep hill. In such a case the engine is speeded up so as to develop its full.mitput of power. The weight at the end of the 'lever is unable to respond to such rapid oscillations; consequently, a severe thrust is brought to bear at the connection A, Fig. 3. This means that at every swing of the lever (B) a severe impulse is imparted to the ratchets, the 'result of which is that a turning movement is set up in the rear axle, which will exactly and automatically adjust itself to the resistance to be overcome. In such a case as this, where the resistance to be overcome is very great, the lever would swing on a pivot point which it would determine automatically, and which would be very near the point A. As the resistance became less, owing to the inertia of starting the car having been overcome, the pivot on which the lever swings would automatically change its position, until the resistance became normal, as when running on a good level road, when the lever would be pivoting in the point marked C, or as in the example shown in Fig. 2. In this position the drive is practically a direct one from the engine to the back axle.
The actual mechanism employed is, of course, very different from that shown in the figures. The oscillating weights are in duplicate, so that vibration is to a great extent balanced.
As will be seen, the torque delivered to the rear axle is in the nature of a number of impulses, varying in number from about four at high speed of the vehicle (on top gear) to an infinite number when great power is required to overcome some very great resistance. The inventor claims that these impulses have no objectionable effect, and that they need not be considered to be any worse than the uneven irapulses transmitted from an internal-combustion engine. We are, however, hardly inclined to accept this view in its entirety.
It will he noticed that in the accompanying drawings common ratchets with pawls and teeth are shown. Such means am, however, not actually employed, and would, of course, be entirely unsuitable ' for the purpose ; they are merely shown te illustrate the principle. ,
The Mystery ot the Unidirectional Valves.
Unfortunately, Mr. Constantinesco was not able to show us the interior of the clutches he employs for imparting power in one direction and allowing slippage on the return stroke, owing to the patents not yet being completed. This was unfortunate, as the details of this particular part interested us even more than the automaticity of the device. Mr. Constantinesco strongly objects to the use of the word " ratchet," and prefers to call them "valves," as their oscillations allow power to be transmitted in one direction only. We consider the word valve, as applied to this part, as a very appropriate term. We shall be much interested to see the infernal arrangement of this part, as many gears have been made in the past where a reciprocating motion had been transformed into a rotary motion by means of "valves," and we think we are correct when we say that no device yet invented has stood the test of the heavy work, coupled with high speed, necessary to drive the rear axle of a motorcar. Such devices have received the attention of engineers ever since the earliest days of engineering. The general opinion seems to be that no form of such a device has proved itself suitable:. for main driving purposes. If Mr. Constantinesco has solved the problem, he has accomplished. something even greater than the invention of an automatically variable gear.
Power not Wasted but Torque Increased.
It may be thought from a casual glance that power is wasted in swinging the weights at an unnaturally high speed of oscillation. This, however, we are assured is not the case, and that any power so used is stored in the weight and adds to the next impulse given to the valve.
The valves are so constructed that by the movement of a hand-controlled lever they can be made to reverse, and so to impart movement to the car in either direction. This is a very important point, as by this 'arrangement the valves farm very convenient sprags, and would effectually prevent &car from running. back should failure of brakes occur, or, if brought into action when the car was standing, would prevent it running, downhill forwards and enable it to be left on the steepest inclines with safety.
A neutral position is also provided, which would enable the car to be left with safety while the engine is running, as, without such an arrangement, should the speed of the engine become accelerated by any chance, the car would move forward, there being no clutch or gear disengagement.
The various models shown us demonstrating the various steps made towards completion showed great ingenuity, and were evidently the result of long contemplation and a thorough knowledge of the scientific principles entailed. 1-Ve shall await the completion of a 'finished model fitted to an up-to-date vehicle with great interest, particularly as it is' the 'inventor's considered opinion that the reciprocating parts of the torque converter could readily be balanced by the unbalanced moving, parts of a singlecylindered engine, and that such an engine should be producible capable of undertaking the work of moving quite a substantial load.