Historical Notes: Steering Gear
The author must admit that in spite of having nourished a warm regard for the early Bollée machines (even to being party to a bribe to the curator of the museum at Le Mans in order to obtain a private view of the exhibits there only to find that the cars had been removed and nothing remained but what seemed to be an endless collection of stuffed seagulls), he knew nothing of how the "land torpedo" was steered. He was due to find out, and that right speedily, for "Casque's" Bollée chose to fill its electrical department with water during the recent "Brighton," and the author was destined to push quite heartily, rain and the gale causing the sight (clouded by the usual spots) to be fixed fairly rigidly upon the steering gear. Indeed, there was nothing else to look at.
So it came about that, standing in a certain barn off the Brighton road, conclusion was reached that a small witch left over from Hallowe'en had caused the stoppage, and that the history of steering gear was a fascinating thing, worth looking into.
The subject is interesting as providing an example of a component part of the motor car that appears to have gone through a period of retrogression. The direct-acting tiller, so common in the early Panhard and other cars before the turn of the century, even before it was alleged to have contributed to the untimely, death of Emille Levassor himself, was soon considered dangerous if any worthwhile speeds were to be indulged in. Yet, going back to the steam-car era before 1840, Cugnot used a geared system of steering, as did Hancock, Gordon and some others. Admittedly they usually pivoted their axles in the middle, and this meant that the shocking roads of the period could transmit terrible blows to the driver's arms, due to the leverage available to the "bump," yet Pecqueur's 1828 waggon even had a "rack-and-pinion" steering, so that there is most certainly "nothing new under the sun." There has just recently, too, been a picture of an even earlier "Chariot à Voiles" published by the Science Museum, which had individually pivoted wheels and, for cyclecar enthusiasts, "wire-and-bobbin" steering. Perhaps the vast improvement in geometry introduced by Ackermann, and rediscovered by the motor-car designer, made people tend to be careless, or perhaps the word "tiller" is itself misleading. Was the tiller-steered Lanchester of 1911, even with its 6 lb. of lead in the handle, worse technically than M. Vacheron's wheel-steered Panhard in the 1894 Paris-Rouen trial? Interesting; but, as usual, a crystallisation took place, and the standard steering gear became common, at least for the heavier cars, just about the turn of the century. It comprised a steering wheel, a column, a worm reduction gear, a cross-shaft, and a drop-arm which connected up with the standard Ackermann linkage. The only outward sign of progress down the years was the reducing angle between the column and the horizontal, but, as usual, outward signs were apt to be misleading.
Before going on to discuss the real progress, however, it is proper to consider how the geometry of the steering itself grew. The "two-pivot forecarriage," to use the contemporary term, was patented by Rudolph Ackermann in 1818, although some give Lankensperger the credit for the idea, but whichever of them it was the idea originally suffered from the severe limitation imposed by the fact that the steering arms were parallel, and therefore the wheels tended to skid on the corners due to the perpendiculars from the wheel centres failing to meet at a common point. Jeantaud overcame this fundamental defect, and thus "Ackermann-Jeantaud" is probably the fairest description of the system now commonly employed. Other methods of achieving the same thing were tried, but failed for reasons that need hardly be enlarged upon, but particularly on account of the added complications involved. "Worm and nut," "worm and wheel" or "worm and sector" were the three main types of steering box used, but ball or roller bearings were unusual and provision for taking up the inevitable wear was sometimes altogether absent. Now it might be thought that this would have resulted in heavy steering but such was by no means always the case, as many modern owners of veteran cars will readily attest. Indeed, some steering gears of 1903 or thereabouts can put their modern equivalents almost to shame, and a good "Edwardian" example, complete with ball bearings and full adjustment for wear (the 1908 Hutton is a very good example), are as near perfect as this sort of mechanism will ever be. They were, of course, expensive to produce, but were very lovely to look at, and to appreciate just how good they really were it is only necessary to recall some of the horrid, stiff, insensitive things that were fitted as "worm gears" to many cars even after 1930, until the better alternatives became more available. It would, perhaps, be fair to say that the worm reached a peak about 1914, then went backwards during the "cheapening" process, except the best examples, which merely maintained the high standards set in the closing days of the "Edwardian era." Needless to add, there were many exceptions to this rule and Lord Montagu, the then editor, was moved to write in The Car Illustrated in June, 1906: " ... but one thing is certain, that sufficient attention has not been given in the past to the various joints in the steering gear. Also, there is often too much backlash between the steering wheel and the front wheels, and it is sometimes impossible to take this up without taking down the whole gear ..." The materials of which the various steering parts were made received much attention during the pre-war years and during that period, prior to 1914, some people hesitated to risk the ball-joint with its difficult stress problem around the neck and stuck to the more easily stressed, but less beautiful, knuckle-joint for all steering purposes. Anthony Heal's Fiat is a good example that survives, and it must be confessed that this idea certainly engenders more confidence as far as 100-m.p.h. motoring on a 40-year-old axle is concerned than does the ball-joint.
A high degree of empiricism necessarily entered into the design of the worm box, irreversibility imposing severe strains upon the steering mechanism, and reversibility making life very tedious for the driver. The degree of "semi-reversibility" achieved, thus allowing a happy compromise between the all-essential "feel" and "deadness," was the standard by which the steering gear was judged, and worm angles of between 14 and 17 degrees seem to have been most commonly chosen to achieve this desirable end. Unfortunately, during the later worm days a bad tendency arose, chiefly encouraged by certain American designs, to make the operation of steering completely irreversible and therefore hopelessly low-geared, perhaps due to the increasing proportion of women drivers, or to the need to cut cost, or both. In extreme examples a skid on wet wooden blocks was quite "uncatchable," and at one time someone used to sell small knobs for, attaching to the spokes of the steering wheel so that the whole giddy apparatus could be wound rapidly round like that of a traction engine! But the answer lay at hand in the new systems being developed, that permitted higher mechanical efficiencies together with automatic wear compensation, without the cost of the better worm systems.
The Marles, afterwards the Marles-Weller, worked on the double cam and roller system, an hour-glass-shaped double cam being rotated by the column, this moving a hardened-steel roller backwards and forwards through an angle of about 30 degrees; this cam communicated its motion to the drop-arm, about 1 3/4 turns of the steering wheel representing the 60-degree arc of movement.
Another alternative, the Bishop, consisted basically of about two complete turns of a "square"-sectioned worm thread whieh was engaged by a conical roller of the same section as the worm "hollow" and which moved up and down the axis of the worm when the latter rotated. Both these gears, together with the Burman-Douglas, began to be popular from the middle to the end of the vintage period.
In application they suffered sometimes, especially in combination with the early independent front-wheel suspension systems then coming into use, from a certain "sponginess" of feel, but it is difficult to blame other than the geometry for this undesirable characteristic. They also suffered, in no small measure, from being screwed down to chassis that were becoming flimsier and flimsier, so that in at least one well-known case, the torque reaction from the steering box succeeded in bending up the top flange of the chassis side-member, which certainly explained the "spongy" feeling, and eventually invariably loosened the bolts attaching the steering box to the motor car itself. What R.A.S.C. officer during the war does not recall this standard "catch" point on the A.B. 406 inspection? (or was it the platoon sergeant who did the inspection?).
There followed a period when proprietary steering gears commenced to operate their steering-arms sideways instead of backwards and forwards; and all this seemed to prove was that there was a very strong argument in favour of the rack-and-pinion scheme, now, sure enough, rapidly coming into favour. Thus do we enter a new era where the accent swings back from the specialist to the individual manufacturer, a practically unique set of circumstances in the history of motor-car accessories.
Taking an unbiased view, it is not usual to be able to say with truth that motor-car design ever reaches finality, but here, surely, is a component part that does come very near to it.
Most modern cars seem to be far too "dead" in the steering to enable the driver to develop his art properly, and it would still be difficult to think of anything better than a vintage Bugatti, for example, in this connection. Admittedly, there are allied problems, and the modern "all-in-one" construction of body and chassis is not usually capable of transmitting that indescribable "feel" that allows the experienced driver to know all the time "how far things have gone," but some modern cars do seem to steer quite badly. No doubt there are many sound technical arguments in favour of the modern system, but let us be beastly and recall some comparatively recent comments of experienced test drivers. "... it is perhaps the steering which damps the driver's ardour ...," writes one such about a post-war car: "... it is heavy in the spongy sense at low speeds, and light but inclined to be vague at higher speeds" We will pass over his comments on the amount, of play after but 3.000 miles and pass on to "... the high-geared steering is as satisfactory as the gearchange. It handles in such a fashion that one feels that it would be entirely satisfactory as a high-speed car . . this applying to an Edwardian de Dion Bouton! Again, the modern disconnected feel is experienced . . about a £1000 modern car, and " ... the car steered with beautiful precision ...", Kent Karslake's view of the 1909 Napier.
No doubt it is rather unfair to both sides to select such vintage views to suit a particular argument. but would the fair comment on the story of the steering gear run soon-thing like this? — the best of the modern cars are not as far advanced over the old as they ought to be, while the best of the old are at least as good as the worst of the new?
All very complicated, so what shall we say of power steering; or the fact that the B.R.M., according to Stirling Moss, had . . . No! let's close on a charitable note! "A. B. C."