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Springs​—Metal in Action

By “Awake!” correspondent in Canada

IMAGINE driving your car through heavy traffic and then, as you take your foot off the accelerator pedal, nothing happens! The pedal stays down and your car continues its excessive speed. Quick action in applying extra pressure on the brakes may stop your car in time. But such an emergency seldom develops. Why? Because of a small, reliable spring that returns the accelerator pedal to its neutral position when you release foot pressure.

Leading the busy lives that we do in a highly mechanized society, we have come to take springs for granted. Yet springs play a vital role in the things that we use daily, from cars to airplanes, from typewriters to computers, from clocks to washing machines, from mousetraps to mattresses. If the object operates mechanically, chances are it has one or more springs fulfilling an important function somewhere in its operation.

Origin of Springs

Although we observe springlike action in created living things, particularly in grass, plants and trees, as far as man-made springs are concerned, they may have been employed from the very earliest times, when men began to be forgers of copper and iron. (Gen. 4:22) Metal springs dating back to early history (not, of course, as early as pre-Flood days) have been found all over Europe and Asia. These are usually in the form of spring-type clasps, and they were made of copper or brass, hammered into shape by skilled craftsmen. It appears that these early people even used a fastening device to help to hold up clothing in much the manner that a safety pin might be used today.

One of man’s early uses of spring energy was in a weapon​—the bow. This was followed by the introduction of large catapults that were used to hurl stones or other missiles at an enemy. These machines were of massive size. By means of sudden release of tension on wooden beams or on twisted cords of various fibers and materials, huge missiles were hurled with tremendous force, greatly damaging enemy fortifications. The Jewish historian Josephus describes the power of the Roman catapults used in the siege of Jerusalem. He says that they could hurl stones of a talent in weight a distance of two furlongs, or a quarter of a mile (.4 kilometer). (A Greek talent as used in Roman times weighed 61.6 pounds [27.9 kilograms].)

The Bible also tells us that King Uzziah (829-777 B.C.E.) had his engineers design engines of war for the defense of Jerusalem, these being capable of shooting arrows and great stones from the city’s towers. What type of power these engines employed is not stated, though it was likely that they used some sort of spring action (certain catapults used counterbalancing weights).​—2 Chron. 26:15.

Further refinements in the use of spring action came with the development of the crossbow, which allowed the spring energy to be stored up or retained until it was released by a triggering device​—indeed a devastating weapon!

Springs in Timepieces

Man’s desire to know what time it is has played an important role in the development of springs as we know them today. Although historical evidence varies, it is believed that mechanical clocks first made their appearance shortly after the year 1000 C.E. and were powered by weights, not springs. These clocks were usually found in the towers of abbeys and churches.

However, as early as the beginning of the fourteenth century, watchmakers started to use springs as a source of power in their timepieces. These early craftsmen continued to improve spring quality and design, so that by the eighteenth century the flat-coil power spring was in general use in clocks and watches. Because the accuracy of their timepieces depended so much on the quality of the spring they used, these early watchmakers often became spring makers. Their constant desire for a better spring encouraged them to experiment with different methods of making steel. Eventually, alloy steels were developed that resulted in better springs and more accurate timepieces.

Materials Used in Springs

Today it is estimated that there are over 50 different compositions of materials and alloys available to the spring manufacturer. A hard-drawn wire that might be used to produce springs of the type found in mattresses is commercially inexpensive and suitable for this application. However, the same material would not be selected for use in a valve spring for an automobile engine, where heat, great stresses and fatigue would soon destroy an ordinary spring. In this case, the spring maker would likely select an oil-tempered alloy wire that would stand up under this severe application. Some springs will withstand heats up to 1,100 degrees Fahrenheit (593 degrees Celsius). Modern aircraft and spacecraft require spring alloys that are able to undergo extreme temperature changes.

The introduction of electric motors and the many modern electrical appliances that we enjoy in our homes today created a need for springs that could also serve as electrical conductors. The more common materials used for this purpose are the phosphor bronze and brass spring wires. These copper-based wires generally have lower resilience than most other materials. Such springs are not as strong as those made of steel wire. But because they are good electrical conductors, they are frequently used in electrical switches or to apply the pressure on the brushes found in motors.

There is no doubt that springs will play an important part in the mechanical things that man builds in the future. Meanwhile, the next time you put your foot on the accelerator pedal of your car, be thankful for the little spring that returns the pedal to its place and allows you to drive safely to your destination.