Under the Hood

The Under the Hood Channel explores the systems that make your car function correctly. Learn about car parts and systems and how to do routine maintenance.

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I see many dump trucks with wheels on two rear axles on the ground and a third axle with elevated wheels that can be lowered. These seem to be used when the truck is full -- but why include what must be expensive hardware to raise and lower the wheels? Why not just keep them down at all times?

What does that funny "H" pattern on my car's gear shift have to do with my transmission? How does it make the car change gears? And when I mess up and hear that horrible grinding sound, what is actually grinding?

By Marshall Brain & Cherise Threewitt

Take diesel-engine technology, throw in a two-stroke cycle, and you've got the basis for the huge engines found in trains and big ships. Learn about the diesel two-stroke engine!

By Marshall Brain

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Ever wonder what the difference is between a gasoline engine and a diesel engine? Diesels are more efficient and cheaper to run than gasoline engines. Learn what makes diesel engines different!

By Marshall Brain

Gear ratios are what allow a car to reach a high rate of speed or climb a steep hill. Learn about gear ratios, gear trains and planetary gear systems.

By Marshall Brain

Surprisingly enough, horsepower actually does refer to the power of horses. But over the years it’s become a valuable measurement for all kinds of machinery. Learn how horsepower is calculated and what it means to the automobile industry.

By Marshall Brain

If you have a car chances are you also have a tire-pressure gauge. Learn how this pen-sized device measures air pressure and why the little stick inside doesn't just fly right out the back!

By Marshall Brain