Transmission (mechanical device)

A transmission is a tool for machines.

It uses many gears to work. Gears are wheels with teeth that lock together.

This tool changes how fast a machine moves. It can also change how strong it is. This helps a car go fast or climb hills.

Some people use a stick to change gears. This is called a manual. Other cars change gears by themselves.

Bicycles use these tools too. Some use gears to help you pedal.

Machines need these gears to run well. It is a very smart way to move!

A transmission is a device that uses gears to work.

Gears are wheels with teeth that lock together. This tool changes how a machine moves. It can change the speed or the direction of a spin. It can also change the strength, which is called torque.

Many machines use transmissions. Early ones helped windmills and steam engines. Bicycles also use them to help you pedal.

Cars often use manual transmissions. In a manual, the driver uses a gear stick to pick the gears. Most modern cars use automatic transmissions instead. These change the gears by themselves. This keeps the engine running at its best speed.

Some cars use a CVT. This is a type of transmission that changes speed smoothly. It does not have fixed steps like other gears. Instead, it moves through a continuous range of speeds. This can help the engine run at one steady speed while the car moves.

A transmission is a mechanical device that helps machines move. It is also called a gearbox. This tool uses a gear set to change how a machine works. A gear set is just two or more gears working together.

The transmission can change the speed of a machine. It can also change the direction of rotation. It can even change the torque, which is the strength of the spin. This makes the transmission a very important part of many machines.

How does a transmission work? It changes the ratio between the input speed and the output speed. The input speed comes from an engine or motor. The output speed is what moves the wheels or the machine.

Some transmissions have fixed gear ratios that never change. Other types have variable ratios that can change. A variable-ratio transmission can have many different steps. It can also be continuously variable, which means it changes smoothly without any steps at all.

People have used transmissions for a long time. Louis Renault invented the mechanical transmission. He was also the person who founded the Renault company.

Early versions were used in windmills and steam-powered devices. They also helped with horse-powered tools. These early machines used gears for things like pumps, mills, and hoists. These tools needed the right amount of strength to do their jobs.

Modern cars use many different kinds of transmissions. Most gasoline or diesel cars use 4 to 10 forward gears. They also have one gear for moving in reverse.

In the US, automatic transmissions became available starting in 1939. Today, automatic transmissions are in more than two-thirds of cars globally. Electric vehicles are different from gas cars. They usually use fixed-ratio or two-speed transmissions. This is because electric motors can work well at many different speeds.

You can see how transmissions work in things you know. Bicycles use gear transmissions to help you pedal. Some use a derailleur gear, while others use a hub gear.

Even helicopters use transmissions to turn their rotors. Some wind turbines use a special type of gear called a planetary gear. This helps the machine handle huge amounts of strength. Whether it is a small scooter or a large tractor, transmissions help keep things moving smoothly.

A transmission, often called a gearbox, is a mechanical device that manages power in a machine. It uses a gear set, which consists of two or more gears working together, to control motion. By adjusting the relationship between gears, a transmission can change speed, the direction of rotation, or torque. Torque is the rotational force or strength of a spin.

This device is essential for ensuring that a machine operates efficiently under different conditions. Without a transmission, an engine might spin too fast or lack the strength to move a heavy load.

The fundamental mechanism of a transmission involves changing the ratio between input speed and output speed. The input speed is provided by the engine or motor. The output speed is the final speed delivered to the wheels or the machine's parts.

For example, in an internal combustion engine (ICE), the rotational speed can range from 600 to 7,000 rpm. However, a vehicle's wheels might only need to rotate between 0 and 1,800 rpm. The transmission bridges this gap by using different gear ratios to match the engine's power to the vehicle's needs.

Transmissions are categorized by how they manage these ratios. A fixed-ratio transmission uses a single, unchanging ratio to increase or reduce speed. These are used in specialized machines like helicopters or wind turbines. In a wind turbine, the first stage often uses a planetary gear. A planetary gear is a specific design used to minimize size while handling high torque, which is the heavy rotational force from the wind.

Other machines use multi-ratio transmissions, which provide several discrete gear steps for different situations.

Manual transmissions require a driver to select gears using a gear stick and a clutch. The clutch is a device that connects or disconnects the engine from the transmission. Early manual designs used straight-cut gears, which are also called spur gears. These gears make a loud whining sound when they spin. While noisy, they are very strong and are used in racing cars, motorcycles, and heavy machinery like tractors. Modern cars mostly use a synchromesh design. This system synchronizes the speeds of the input and output shafts to allow for smoother shifting.

Automatic transmissions remove the need for a driver to change gears manually. A hydraulic automatic transmission is the most common type. It uses planetary gearsets operated by hydraulic fluid. Instead of a friction clutch, it often uses a torque converter to connect to the engine.

Another advanced type is the dual-clutch transmission (DCT). A DCT uses two separate clutches for odd and even gear sets, functioning like two manual transmissions in one housing. There is also the continuously variable transmission (CVT). A CVT does not have fixed steps; instead, it changes seamlessly through a continuous range of ratios. This is often done using two pulleys connected by a belt or chain.

History shows how these devices have evolved to meet new technologies. Louis Renault, the founder of the Renault company, is credited with inventing the mechanical transmission. Early applications were found in windmills, steam-powered devices, and horse-powered tools like mills and hoists. In the United States, automatic transmissions began appearing in cars in 1939. Today, automatic transmissions are used in more than two-thirds of all cars globally. Electric vehicles (EVs) use different logic. Because electric motors work efficiently across wide speed ranges, EVs often use fixed-ratio or two-speed transmissions.

Maintaining a transmission is a matter of complex engineering and physics. Gears are designed to follow strict standards, such as ISO 6336, to ensure they are safe. If a gear is not designed correctly, it may suffer from failure mechanisms like wear, pitting, or fatigue fracture. These failures are caused by friction, contact pressure, or a lack of lubrication.

Even the sound of a vehicle can tell us about its transmission. The noise and vibration produced by gearboxes can be used by scientists to study urban roadway noise. This helps engineers design better noise barriers for cities.