From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'The Motor' magazine about a new S.E.V. automatic advance magneto.
| Identifier | ExFiles\Box 37\1\ scan 214 | |
| Date | 18th February 1920 | |
| The Motor | 118 | February 18, 1920. Handwritten: X 3949 NEW MAGNETO WITH AUTOMATIC ADVANCE. A French Design Embodying a Simple Self-timing Device. THE S.E.V. electrical productions have an excellent reputation and are largely used on French cars; consequently the new automatic advance magneto, made by the S.E.V. concern, is likely to create a great deal of interest. Many devices for rendering a magneto self-timing have been introduced in the past, but practically all magnetos today either have hand control or a fixed timing point. Automatic advance devices have hitherto involved a certain amount of extra complication, which for general use has been undesirable. In this new S.E.V. magneto complication is avoided, as the automatic advance is nothing more complex than a flexible or spring coupling between the drive and the armature, and at the same time it embodies a principle dependent on centrifugal force, which produces an angular difference between the drive and the armature, so that as the engine speed increases, the spark occurs proportionately earlier in the stroke, thus ensuring maximum power. [Image Caption 1] General view of S.E.V. automatic advance magneto, showing how the extra mechanism is compactly arranged in an extension of the usual design. (Image label: Advance Casing) [Image Caption 2] The automatic advance unit and flexible coupling complete (on left) and taken apart, showing its simple construction and position of the weighted springs when the machine is at rest. (Image label: Weighted Springs) Advantages of the Automatic Advance. Automatic advance ensures an effective spark at starting and at low speeds, and all risk of a backfire at starting is eliminated by reason of the timing always being set at maximum retardation. The ignition always occurs at the correct time to ensure maximum efficiency and flexibility at the particular engine speed obtaining and independently of any action on the driver's part. The element of uncertainty which is inevitable with manual control of the timing is thus eliminated. One advantage of this is that it tends to improve the fuel consumption. With the exception of the automatic advance device, the S.E.V. magneto is of standard construction. The advance device and flexible coupling are contained in a casing at the driving end of the machine, and it comprises two discs, each being keyed respectively to the drive shaft and the armature shaft. These discs are connected together by a pair of curved springs, to which are attached weights of segmental shape. These weighted springs form the centrifugal element which produces the advance and retard effect, and they also provide an elastic coupling, which absorbs any shocks and vibration that might otherwise be conveyed to the armature. Another advantage is that any slight want of alignment in the two shafts is compensated for. Springs of three different strengths are provided, No. 1 giving a maximum advance of 25 deg. at 1,600 revs., No. 2 25 deg. at 1,800 revs., and No. 3 25 deg. at 2,000 revs. On another type of machine the advance is 36 deg. at 2,500 and 3,000 revs., according to the spring used. How the Centrifugal Device Operates. The weighted springs have respectively each an end anchored to a pin fixed in one disc and the other end anchored to a pin in the other disc. The action is as follows:— When the magneto is at rest the springs are drawn in by their inherent tension toward the centre, and each pair of pins is almost adjacent, as shown in the illustration, the discs then occupying a position relative to each other equivalent to the fully-retarded position. As the armature is speeded up, the weighted springs tend to expand more and more; this means that the four pins must occupy a position proportionately wider apart, and this can obviously only occur by angular displacement of the discs. The S.E.V. magneto is handled by Franco-British Agencies, 9, Wingate Road, Kensington, S.W. STIMULATING OUTPUT. There is an element of sport in the motor industry which is necessarily lacking in many industrial pursuits. This fact is all to the good, and should be of great assistance in many ways. It is a well-known fact that concerns which have in the past habitually competed in racing and sporting competitive events have found that their employees displayed the greatest interest in the behaviour of the cars and the utmost willingness to work well and hard in their production. While present conditions preclude an immediate revival of such events, it would be all to the good if some such sporting atmosphere could be infused into the routine of ordinary production. To get department to vie with department in increasing output and to induce an interest in the weekly output of the factory as a whole is a problem so difficult that no avenue should be neglected which might lead to its solution. In this connection it is interesting to note that in many factories to-day efforts are being made to stimulate competition and the sporting instinct in regard to work and output. D20 | ||