Green Light Means Go
You put your foot on the gas pedal, push down, and expect to start moving. Ever wonder what happens beyond the gas pedal? Sure, your car accelerates, but what is going on from the gas pedal to the engine to the wheels?
Gas Pedal
When you step on the gas pedal you initiate a process that delivers air and fuel to the engine. As the gas pedal is pressed, it turns a pivot that in turn pulls the throttle wire. The throttle wire is connected to a throttle linkage. That linkage serves to control a valve that regulates the air intake to the engine. The more you step on the gas pedal, the wider open the valve becomes and the more air is let in. Various sensors monitor this airflow and inject fuel accordingly to maintain an optimum ratio of air to fuel.
Four Stroke Combustion Engine
Almost all cars use a four stroke combustion engine, which turns an air/gasoline mixture into energy.
- Intake Stroke – The intake valve opens and the piston moves down to let the engine take a mixture of air and gasoline into the cylinder.
- Compression Stroke – Compresses the air and fuel. By compressing, or forcefully pushing the air and gas together, the mixture will explode with more power.
- Combustion Stroke – The spark plug emits a spark and ignites the gasoline in the air/fuel mixture within the cylinder. This causes an explosion which pushes the piston down.
- Exhaust Stroke – The piston hits the bottom of the cylinder and the exhaust valve opens to let out the exhaust and send it on its way through the exhaust system, to the tailpipe.
Connecting Rod and Crankshaft
In an internal combustion engine, the linear force of the pistons is converted into a rotational force by the crankshaft. The connecting rod connects the piston to the crankshaft. It rotates at both ends so its relative angle can change as the piston moves up and down. The crankshaft rotates – or transfers the linear motion of the pistons into circular, or rotational, motion.
Transmission
The crankshaft connects to the transmission when the car is put into gear and the clutch is engaged. When the clutch is disengaged (for example, by stepping on the clutch pedal in a manual transmission car), the crankshaft disconnects from the transmission.
The transmission controls the power generated via the crankshaft. It regulates the power as it is transmitted to the wheels. This process allows the driver to control the speed and power of a car. This is done with different speed/power ratios known as gears, e.g., 1st, 2nd, 3rd, and so on. First gear gives power, but not much speed. Fifth gear is a good cruising speed, for highway driving in particular, as it delivers low power, but maintains high speed.
The transmission is connected to the drive shaft, which is connected to the axles via a differential. The axles are, of course, connected to the wheels. When the transmission rotates the drive shaft, it turns the axles, which rotate the wheels – and all of this put together makes your car go.
At AAMCO Minnesota we know all about the parts and systems of what happens from gas pedal to the wheels. When something goes wrong it’s time to schedule an appointment with your local AAMCO Minnesota mechanic for reliable, trusted auto repair.