Humble bumpers noe perform multiple functions

By T. Uncle

BUMPER bars. The name pretty much implies what their intended function on a car might be.

And today, bumper bars actually do the job they were originally designed for, although that was not always the case.

It is not so long ago that the thin strips of metal attached to both the front and rear of many cars were little more than cosmetic devices.

Often frail to the point of easily being dented by little more than finger pressure, some of the so-called bumper bars attached to cars about a decade ago were more a liability than a protective device.

This contrasted with the heavyweight bumpers used on cars back in the 1920s. These seriously tough bumpers not only protected the car from outside attack by roadside objects such as fence posts, animals or even other cars, but were also capable of inflicting mighty damage on whatever they struck.

This thought didn't seem to occur in the days before true motorcar safety consciousness.

Gradually, though, the idea of what a bumper bar should be used for changed, as aesthetics became more and more important. Excessive complexity, and the ability to intimidate, became the governing factors in bumper design.

This approach to bumper design reached its zenith with American cars in the 1950s and early 1960s, when some horrifically aggressive cars cruised the roads.

The jutting, torpedo-shaped attachments used on the front of Cadillacs from the 1950s were seriously threatening to other cars or slow-of-foot pedestrians, but were also useless when it came to providing the protection they were allegedly intended for.

If they did hit something big and heavy enough to actually suffer damage themselves, that damage was usually telegraphed through to the rest of the car's rigid, essentially unyielding structure. The more ornate the bumper, the more expensive the damage was to fix.

Then followed the era of the less massive, less injurious, but equally unprotective designs that persisted through until the 1970s, before giving way to the more socially responsible "safety" bumper bars.

Styling, rather than function, had dictated the direction of bumper design until the industry became aware that two factors were not being adequately addressed: First, the beautifully integrated bumpers were not really providing any protection for the rest of the car -- let alone any hapless pedestrians -- and second, that the cost of repairs, even in small accidents, was excessive.

The first attempts at designing bumpers that covered all bases represented a low point in front- and rear-end aesthetics, especially in America, where legislative requirements concerning bumper behavior in low-speed accidents (largely dictated by the insurance industry that wanted to reduce repair costs) produced some really ugly results.

Mounted on special, collapsible members that were designed to absorb shock before it reached the body, these big, flat, unaerodynamic, rubber-coated crash barriers looked more as if they belonged on dodgem cars than on the highway.

Fortunately, that is not the case today. Where bumpers are concerned, the car industry has learned to combine good looks with sound design.

In most cases, they are so well integrated into the design that it is difficult to believe there is any bumper at all.

Most are constructed from a flexible, self-repairing molded plastic, often using a honeycomb sub-structure to provide strength and flexibility with light weight.

The front bumper also doubles as part of the aerodynamics of the vehicle and may even be involved in directing airflow into the engine compartment.

While it does all this, it is also designed to resist any damage at all in low-speed accidents -- up to about 8km/h in most cases -- and to progressively absorb impact shock at higher speeds before it reaches the actual structure of the car.

Even when this starts to happen, the bumper remains part of the overall structure designed to minimize the effects of a severe front- or rear-end impact on the all-important central safety "cage" that forms the central section of every modern passenger car.

So today, the humble bumper performs the multiple role of protecting the vehicle itself from damage, while posing a lesser threat to anything it might strike -- including a pedestrian -- and also being able to regenerate itself in a low-speed accident. And it adds to, rather than detracts from, the car's styling.

It is a good example of how clever car designers have become.