Transmission (mechanics) facts for kids
A transmission, also known as a gearbox, is a system of gears that work together. You can find transmissions in many machines, but they are most commonly known for their use in cars.
In a car, the engine creates power by spinning a part called the crankshaft. The transmission's job is to take this spinning power and send it to the car's wheels. It does this by using different gears. These gears help to slow down the spinning motion from the engine. They also make the spinning motion stronger, giving it more torque. Torque is the twisting force that helps the wheels push the car forward. Most transmissions also have a small opening, like a vent, to let out hot air.
Contents
How Car Gears Work
A car's transmission has several gears. Each gear changes how much power and speed goes to the wheels. This is why cars have a first gear, second gear, third gear, and often more. There is also a reverse gear for backing up and a neutral setting where the engine is not connected to the wheels.
Automatic vs. Manual
There are two main types of car transmissions:
- An automatic transmission changes gears by itself. The driver just puts the car in "drive" and the car handles the rest.
- A manual transmission needs the driver to choose when to shift gears. This is done using a gear stick and a pedal called a clutch. Manual transmissions are sometimes called "standard" transmissions. However, in places like the U.S., automatic transmissions are much more common.
What is a Layshaft?
Inside some gearboxes, like those in cars, there's a part called a layshaft. This is a middle shaft that spins constantly when the car's engine is running and connected. All the gears on the layshaft spin at the same speed. The layshaft helps to transfer power between other parts of the gearbox. The oil inside the gearbox usually reaches the layshaft's height. This way, as the gears spin, they splash and spread oil to keep all the parts lubricated.
Transmissions in Other Machines
Transmissions are not just found in cars. Many other machines use them too. For example, bicycles have a type of transmission. You can easily see the gears on a bicycle. When you shift gears on a bike, you are changing how much effort it takes to pedal and how fast you can go. This is similar to how a car's transmission works, but on a smaller scale.
Images for kids
-
Single stage gear reducer.
-
Tractor transmission with 16 forward and 8 backward gears
-
Amphicar gearbox cutaway w/optional shift for water going propellers
-
The main gearbox and rotor of a Bristol Sycamore helicopter
-
A diagram comparing the power and torque bands of a "torquey" engine versus a "peaky" one
-
Shimano XT rear derailleur on a mountain bike
