Wyman Anthony, age 10, of Ford Road, N.C, for his question:
What is a spark plug?
An automobile engine is a job of team work. The team mates are pistons and cylinders, valves and spark plugs plus thousands of other machine parts working together. Each part does a special job. By itself, a spark plug or any other part is useless . it can work only with its team mates. If one team mate fails, the engine cannot operate smoothly and it may break down.
A little spark plug in the engine of an ordinary car uses may":; 20,000 volts of electricity. The shock from this jolt of energy would kill you, or at least injure you seriously. So lefts put the brakes on our curiosity about spark plugs. In fact, a sensible young person would never examine the inside of a car without the help of a trained expert.
A garage man is the Ideal person to show you how the spark plug works and some garages have models to demonstrate this small bolt of lightning in action. When a spark plug is not connected up with, the other machine parts in the car engine, it is quite safe to hold it and examine it. But the real thrill comes from seeing this little powerhouse in action.
In a car engine, one end of a spark plug fits snugly inside each of the metal cylinders. You cannot see it at work, which is why it is well worth while to find a garage which has a display model in which you van see what goes on through the sturdy walls of the cylinder. The cylinders are the little powerhouses that turn the gasoline fuel into the energy to drive the car.
Each cylinder is shaped like a tin can with one end removed. There is a valve to let in air and gasoline vapor and another valve to let these gases out after they have been ignited.
A moveable plug called the piston fits snugly into the open end of the cylinder and with each burst of energy it pushes up the cylinder almost to the top and down almost to the bottom.
The tip of the spark plug waits for just the right moment to do its work in this operation. As the piston goes down, air and gasoline vapor rush In to fill the cylinder. Then the piston moves up to squeeze or compress the mixture of gases in the little chamber. Now a bolt of electricity shoots between two metal points at the tip of a spark plug. This is the spark which causes the gases to explode with bursting energy. The exploding energy forces the piston down. The cylinder fills up again and the operation is repeated.
The spark plug and the piston are linked to other machine parts, all working together as a team. The spark plug gets its energy indirectly from the car’s storage battery .. which has only about twelve volts of electricity. The ignition system of the car steps up the energy :from the battery and links it with a wire carrying 20,000 volts to each little spark plug.