Figure 3 shows a view of the typical clearances in a compact car and in a standard car. Note that the head clearance at the roof for the normal seated position and the foot spaces are quite similar in both sizes of cars but that the closeness of the windshield and the instrument panel do not allow jackknifing clearance especially in the compacts. You all know this from your own observations. Just bend forward the next time you're wearing your seat belt and imagine that, in an accident, the belt will stretch and your head will be about 6 to 8 inches farther forward. Note the black dots at the hip position which indicate typical stretching of the belt.

Figure 4 is a top view illustrating the right front panel elimination. I am not proposing that the left front panel be eliminated because it is a good place for instruments and a properly designed steering assembly can protect the belted driver from instrument panel contact in that position.

Let us now move on to consideration of the steering assembly.

SECOND PROPOSAL

Redesigning the steering assembly

There is also an urgent requirement for some new treatment of the driver's station in relation to the seat belt and the steering assembly. The typical and essential parts of the steering assembly, as I shall refer to it consists of the wheel, the shaft and its supports, and the gearbox. In my opinion, there are two

major shortcomings of the conventional steering assembly from the standpoint of

crashworthiness.

1. Steering column penetration is an all too frequent occurrence.

2. The energy-absorbing potential of the system is not being fully exploited.

I shall first discuss the penetration problem wherein the column is rammed into the driver's compartment because of structural collapse of the car's front end. Figure 5 shows several types and degrees of column penetration.

ACIR is conducting a special study on this subject. It examines accidents involving standard American cars, compacts, and European cars and its major purpose is to seek relationships between degree of penetration and structural configuration of cars, by examining size, weight, and types of cars as well as location of the steering gearbox relative to the front end. Preliminary results show that there are measurable differences in the frequency of steering column penetration among different types of cars. We are having difficutly, however, in establishing statistically clear relationships between penetration and injury and until this problem is resolved, the report will not be ready for publication. In the meantime, assuming that the final results, with more data, will show significant relationships, I suggest that the designers anticipate the final results and start to work out means of eliminating penetration. It seems a relatively easy thing to do. The advent of the seat-belt era makes it all the more imperative. When the driver is held in position by a seat belt or harness, and the column rams back, there is no escape. What more need be said to stimulate corrective design?

There are many ways to design steering columns so that, when the front structure of the car collapses during collision, the upper end of the column will not be displaced relative to the firewall and instrument panel.

The left-hand group of sketches on figure 6 illustrates several ways in which columns can be divided into an upper and a lower section by means of a spurgear torque drive (or a chain and sprocket drive) so that under longitudinal collapse of the front section of the car the lower shaft is isolated from the upper section by disengaging the gear or breaking the chain. Splines to allow sliding of the lower shaft relative to the upper could also be utilized. Universal joints can also be incorporated, along with initial axial misalinement between the lower and upper sections of the shaft so that end loading of the lower column will cause premature column buckling. Note that all of these suggestions are based

on the principle of dividing the steering column into two sections, fastening the upper column casing securely to the instrument panel and firewall, while allowing the lower, or gear box end, to accommodate the displacement which occurs during front end collapse. There is no point in providing endless descriptions of the possible spectrum of engineering solutions to the problem of steering column penetration. I have no doubt whatever that the ingenuity of the automotive engineers will rise to the occasion if they are given a clear directive, by management, to solve the problem. The requirement is to eliminate steering column penetration. The means are myriad.

Energy-absorbing steering wheels

The second need in steering assembly improvement is increased energy absorption for body contact. ACIR made an attempt in 1959 to evaluate the relative effectiveness of the old-fashioned flat wheel and the newer recessed hub types (recessed hubs are the types now being commonly used). This pilot study found a weak tendency toward reduction of chest injury with recessed hub wheels but there were many uncertainties about the statistical validity of the results. The pilot study was tabled until more data became available and ACIR is now renewing this study. We cannot yet draw firm conclusions about the effectiveness of the recessed hub principle but I suspect that, if the relative improvement over the flat wheel were indeed a powerful effect, it would have emerged more positively in the original pilot study, despite the small amounts of data.

This clue leads me to believe that the effectiveness of the generic recessed hub wheel may be disappointing and I suggest that, in order to achieve a more powerful improvement in safety, the automobile designers turn their talents toward developing an improved form of energy-absorbing steering wheel-something with several times the effectiveness of the present family of wheels. It is quite possible that certain specific designs, within the present family of recessed wheels, are far superior to the generic wheel which I am discussing. 49-959-66-pt. 2--20

However, our data do not allow us to identify such wheels and measure their effectiveness. It would seem that a sensible approach to redesign would be to retain the recessing principle, and add a separate displacement type of energy absorber to utilize at least 6 to 8 inches of axial travel while allowing the wheel and column head to move toward the instrument panel. Here the hub could stop and allow the rim to collapse in the final part of the stroke, still protecting the driver from contact with the instrument panel and windshield. There are many possible design variations of this concept and a systematic search to find the best combinations of antipenetrating and energy-absorbing steering assemblies should have high priority for early development. Figure 6 also shows schematics of several possible principles on the right-hand side of the illustration. Here we have a hydraulic shock absorber, or a frangible metal tube which absorbs energy as it peels off segments over a metal die, or a collapsible metal cone. There are many other possibilities.

The new trend of increasing use of seat belts should help the designer solve the problem of axial energy absorbers. The seat belt should (a) reduce eccentric contact of the wheel by other front passengers and, (b) should produce more definable axial loading conditions from driver contact because the lap belt actually controls the torso trajectory of the driver. It may be expected therefore that, with increasing use of seat belts, impacts will be applied by the driver more squarely and more frequently in the plane of the wheel. The situation is ripe for a significant advance in crashworthiness by considering the seat

belt and steering column as mutual components of an integrated restraint system.

Figure 7 illustrates some of these features which could be applied when the seat belt is being used and the entire driver position is considered as it relates to an improved steering assembly.

Integrated safety seat

THIRD PROPOSAL

Even when proposals one and two are applied, two very important restraining functions will still be lacking in the present lap-type seat belt applications. 1. Upper torso restraint to prevent forward jackknifing. 2. Lateral restraint to protect against side impacts.

The

Looking toward the future, the combination lap belt and shoulder harness can partly satisfy these additional requirements. Installing a shoulder harness, however, in one's own car is an extremely discouraging project, much like that of trying to fit a homemade seat belt installation 10 years ago. The problem is first to find a structurally sound anchor point for the shoulder strap and in a position where the strap doesn't slip off the shoulder. To make a good anchor point usually requires a good mechanic with a good engineering sense. chances of early large scale adaption to all types of American cars by the simple expedient of the industry's providing standard shoulder strap anchor points, as was the case for seat belts, seems remote to me because of the difficulty of providing a structurally sound attachment point on hardtops and convertibles, which have no center post to the roof. Because of the aforementioned difficulties I have concluded that another approach, which I shall call the integrated safety seat, will provide a better, more salable and hence more extensively used, solution for the front seat position. I believe that there is great merit to a special type of front seat, designed to resist restraint system loads and incorporating a retractable harness system in addition to improved side restraint and a head rest. Such a seat could be provided in a neat, well-styled package that could be first introduced to the "sporty" segment of the market who now buy bucket seats and who will soon be looking for a new status symbol. This would at least reach part of the market and get the ball rolling. A different solution is needed for the full-width front seat. Standard sedans and station wagons having a center door post should not present a difficult problem to the engineer; so the shoulder harness could be a good solution for this type of car with a full-width front seat.