Understanding Gears in Cars

Diesel Power

• Diesel engines do not need spark plugs to ignite the fuel and air inside the cylinders.
• Instead, the fuel and air explode spontaneously when the piston squeezes the mixture during the compression stroke.
• Diesel contains more energy than gasoline, so diesel cars can travel a greater distance for the same amount of fuel.
• The Porsche Panamera Diesel can travel 44.1 miles (71 km) per gallon.

History of Engines

• In the 1700s, engineers in Britain harnessed the power of steam to turn the wheels of steam locomotives.
• Nicolas Cugnot used a steam engine to power a tractor in 1769, the first self-propelled road vehicle.
• Etienne Lenoir invented the first internal combustion engine in 1869, which burned coal gas inside a metal engine.
• Nikolaus Otto designed a more efficient internal combustion engine that burned gasoline instead of coal gas.
• Otto's engine design is the basis for almost all modern automobile engines.

Internal Combustion Engine

• An internal combustion engine converts the energy locked away inside gasoline into the movement of the car's wheels.
• The engine unlocks this energy by burning the gasoline inside small metal chambers called cylinders.
• The cylinders are tubes cut into a lump of metal called the cylinder block.
• A car engine can have up to 16 cylinders in the cylinder block.

4-Stroke Cycle

• The 4-stroke cycle includes:
  • Intake: the piston moves down, the cylinder takes in air, and the fuel injector squirts a tiny amount of gas into the cylinder.
  • Compression: the piston moves up, squeezing the fuel-air mixture together.
  • Explosion: a spark from the spark plug ignites the fuel-air mixture, driving the piston back down the cylinder.
  • Exhaust: the piston moves back up, forcing burned gases into the car's exhaust system.

Engine Power

• German engineer Karl Benz made the first practical motorized vehicle in 1886, powered by a single-cylinder four-stroke internal combustion engine.
• Modern automobiles are more powerful, with larger engines and more cylinders to burn more gasoline.
• The cylinders in a car engine can be arranged in a straight line or in rows to make a V-shape.
• High-performance cars often have special boosters that squeeze more air into the cylinders, resulting in more powerful explosions and faster speeds.

Gears

• The crankshaft converts the up-and-down movement of the pistons into the turning force of the wheels, called torque.
• Cars use gears to increase the torque that is produced by the engine.
• The gears in a car are metal cogs of different sizes that line up inside the gearbox.
• Low gear is used to get a car moving or to climb a steep hill, with lots of torque.
• High gear is used to cruise along a highway, with less torque.

Braking

• Cars need a way to slow down as well as speed up.
• To slow down, the driver pushes their foot down on the brake pedal.
• The brake pedal is connected to the brakes on each wheel via fluid-filled pipes.
• The force of the foot is transmitted through the fluid in the brake pipes to brake pads at each wheel.
• The pads clamp hard against the brake disk on the wheel, slowing the wheel and reducing the speed of the car.

Diesel Power

• Diesel engines do not need spark plugs to ignite the fuel and air inside the cylinders.
• Instead, the fuel and air explode spontaneously when the piston squeezes the mixture during the compression stroke.
• Diesel contains more energy than gasoline, so diesel cars can travel a greater distance for the same amount of fuel.
• The Porsche Panamera Diesel can travel 44.1 miles (71 km) per gallon.

History of Engines

• In the 1700s, engineers in Britain harnessed the power of steam to turn the wheels of steam locomotives.
• Nicolas Cugnot used a steam engine to power a tractor in 1769, the first self-propelled road vehicle.
• Etienne Lenoir invented the first internal combustion engine in 1869, which burned coal gas inside a metal engine.
• Nikolaus Otto designed a more efficient internal combustion engine that burned gasoline instead of coal gas.
• Otto's engine design is the basis for almost all modern automobile engines.

Internal Combustion Engine

• An internal combustion engine converts the energy locked away inside gasoline into the movement of the car's wheels.
• The engine unlocks this energy by burning the gasoline inside small metal chambers called cylinders.
• The cylinders are tubes cut into a lump of metal called the cylinder block.
• A car engine can have up to 16 cylinders in the cylinder block.

4-Stroke Cycle

• The 4-stroke cycle includes:
  • Intake: the piston moves down, the cylinder takes in air, and the fuel injector squirts a tiny amount of gas into the cylinder.
  • Compression: the piston moves up, squeezing the fuel-air mixture together.
  • Explosion: a spark from the spark plug ignites the fuel-air mixture, driving the piston back down the cylinder.
  • Exhaust: the piston moves back up, forcing burned gases into the car's exhaust system.

Engine Power

• German engineer Karl Benz made the first practical motorized vehicle in 1886, powered by a single-cylinder four-stroke internal combustion engine.
• Modern automobiles are more powerful, with larger engines and more cylinders to burn more gasoline.
• The cylinders in a car engine can be arranged in a straight line or in rows to make a V-shape.
• High-performance cars often have special boosters that squeeze more air into the cylinders, resulting in more powerful explosions and faster speeds.

Gears

• The crankshaft converts the up-and-down movement of the pistons into the turning force of the wheels, called torque.
• Cars use gears to increase the torque that is produced by the engine.
• The gears in a car are metal cogs of different sizes that line up inside the gearbox.
• Low gear is used to get a car moving or to climb a steep hill, with lots of torque.
• High gear is used to cruise along a highway, with less torque.

Braking

• Cars need a way to slow down as well as speed up.
• To slow down, the driver pushes their foot down on the brake pedal.
• The brake pedal is connected to the brakes on each wheel via fluid-filled pipes.
• The force of the foot is transmitted through the fluid in the brake pipes to brake pads at each wheel.
• The pads clamp hard against the brake disk on the wheel, slowing the wheel and reducing the speed of the car.