How Manual Transmissions Work

While manual transmission is an older function, it still holds the advantage over automatic transmission in a variety of different ways. And although your car may be an automatic transmission, learning manual transmission is a useful and often necessary skill to have. If you are just learning how to drive, or you need better assistance in improving your driving skills, you can follow this guide to understand how manual transmissions work and how you can master the skill of driving in a manual setting.

What is a Transmission?

Whether or not you already know how to drive a stick shift car, you may not know how the functionality behind it actually works. In this article, you'll learn a little bit about what transmission actually is, and what happens behind the scenes when you drive an automatic vehicle.

Your car's engine uses and transmits power on a rotational basis, and the power is rotated to many different parts of the automobile at once. When you want to move your car forward, you essentially need to tell the engine to transmit some of that rotational power to the wheels, which is what turn in order to propel you forward or backward.

That's where the transmission comes in. The drivetrain is a part of the transmission that gives that power to the wheels so that you can move forward. In order to transmit this power, though, the gears need to be reduced so that the power can be given to the wheels properly. This is because the wheels turn more slowly than the engine, so accommodations need to be made.

Speed and Torque

There are two different types of power transmitted by the engine: speed and torque. They are distinctly different and must be understood in their differences so that you know how the transmission and gearbox works to deliver the properly selected setting.

Engine speed is how fast the crankshaft spins, typically measured in RPMs. Also known as revolutions per minute, this is what delivers speed directly to the wheels so that you can accelerate or decelerate based on where or how you are driving.

Engine torque is the amount of twisting force an engine creates at its main shaft. This controls the speed of rotation, as well as how hard or how effective the rotation is.

Imagine you are hammering a nail into a piece of wood. Your speed would be how many times you hit the nail on the head per minute, while your torque would indicate how hard you hit it every time. If you hit it really fast, you probably aren't using a lot of power. On the other hand, if you focus on hitting it really hard each time, you are probably sacrificing some speed. This is exactly how speed and torque work in your engine's transmission. You can either have a lot of power, which helps you climb a hill, or a lot of speed, which lets you cruise down a highway in an effective way.

The Gearbox

The gearbox is the area of the transmission that provides different gears for the driver to select based on the driving condition they are in. The settings and gears that come with a gearbox typically include:

  • Standing start gear
  • Hill climbing gear
  • Level surface cruising gear

The lower the gear, the slower the wheels of your car will turn. This is all in relation to the speed of your engine, so it takes a bit of tweaking and adjustment to learn which gears you should be using at different times during your driving experience.

Gearbox Stages

The transmission system goes through many stages, many of which include the gearbox. When you start driving, the gearbox goes to the second stage, with the clutch being the first stage. A modern manual transmission will have four or five different speeds, also known as stages. In addition, the transmission will have a reverse option, as well as a neutral position for use in a variety of different (non-driving) situations.

The most common way to select the different transmission stages is through the constant-mesh gearbox, which is a device with three shafts to control it: The layshaft, the input shaft, and the mainshaft, all of which come in the gearbox casing. The engine controls the input shaft, which in turn affects the layshaft. The layshaft affects the rotating gears on the mainshaft, moving about freely until they are controlled by a synchromesh device.

Synchronizing the Different Gears

Again, the gear ratios found in modern manual transmissions are as follows:

  • First Gear - The smallest gear on the layshaft is locked, granting low speed and high torque to the wheels
  • Second Gear - In second gear, there is an increased speed but a lower torque, which is good for climbing hills
  • Third Gear - A larger layshaft gear contributes to increased forward driving speed but reduces torque even more, making it the ideal gear for low climbing and city-based driving
  • Fourth Gear - This gear is good for when the driver is driving on a smooth plane, such as a highway, as the input shaft and mainshaft are locked together with no increased torque and increased speed
  • Neutral Gear - All gears are in mesh, with gears moving freely around, and no drive is transmitted forward
  • Reverse Gear - One of the idle gears moves between the gears of the two shafts, making the mainshaft reverse in direction, and this gear is typically not synchronized

The synchromesh device, which looks like a toothed ring, is connected to the shaft and is responsible for synchronizing the gears when the driver selects one. The friction on the hub and the gear work together to transmit power to the drive, which turns the gear and synchronizing the speeds of both of the shafts that are in use.

When the driver moves the gear lever even further, this synchromesh ring moves to the hub, until the teeth mesh with the other side of the gear. When they are locked in place, this is what selects the gear setting and keeps it in that setting until the driver chooses something else.

The driver themself cannot make the teeth clash together, since the synchromesh system is designed to prevent human error. This is why it is the most sought-after type of modern manual transmission system in cars that are sold on the market today.