What Is Manual Transmission System? Its Parts and How It Works

A manual transmission is the oldest transmission used in automobiles to date. It uses a driver-operated clutch for engagement and disengagement via the foot pedal. Additionally, a hand lever and a hand-operated gear selector are both capable of doing it. This regulates torque transfer from the engine to the transmission.

In this reading, we’ll explore what a manual transmission is, its diagram, types, parts, and how it works.

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Table of Contents

What is a Manual Transmission?

A manual transmission (MT) is a transmission system for multi-speed motor vehicles that necessitates the driver to manually select the gears by operating a gear stick and clutch (which is typically a foot pedal for automobiles or a hand lever for motorcycles).

A manual transmission is essentially a mechanism that allows the driver to select from various gear ratios to operate the vehicle. Lower gear ratios provide greater torque but lower speed, while higher gear ratios provide greater speed but less torque.

Often referred to as “speeds,” a “six-speed” manual transmission boasts six forward gear ratios.

Conventionally, the gearbox system features a 5- or 6-speed manual transmission. It is standard in a modern base vehicle. The 5-speed types are common on commercial vehicles and lower-end vehicles. Higher-end vehicles like luxury and sports cars feature the 6-speed transmission for the base model. There are also other transmission options available.

Manual Transmission Diagram

Types of Manual Transmission

Below are the types of manual transmissions:

Sliding-gear Transmission

These types of manual transmissions are known as unsynchronized transmissions. Older models of cars feature this invention from the late 19th century. The transmission remains stationary when it is in the neutral position. In the transmission case, the main drive gear and cluster gear kept moving.

Pressing the clutch pedal releases the shifter handle. The shifter handles change the position of the shift linkage and forks and slide a gear to the main shaft. The clutch is released once the gears have meshed.

Constant-Mesh Transmission

These types of transmission are known as synchronized transmission. The drive gear, cluster gear, and main shaft gears are in constant motion. This phenomenon happens because the gears freely spin around the main shaft. We use sliding gear transmissions to lock the gears in place.

A dog clutch also helps to lock these gears in place when needed. The teeth on the dog clutch and main shaft gears lock onto each other and hold the gear stationary. This effect occurs as the shift linkage moves. This transmission uses synchronizers to prevent clashing or grinding while changing gears.

Preselector Manual Transmission

This manual transmission system was also developed before the invention of automatic transmission. It is known as the Wilson preselector, introduced in 1930. The transmission uses a planetary gear system to preselect the gear ratio.

The steering column features a small lever for this purpose. Drivers shift gears by pressing down the foot pedal, which notifies one of the preset gears. The previous gear disengaged immediately after the new gear engaged.

Parts of the Manual Transmission

Below are parts of a manual transmission and their functions:

A clutch disc: allows the torque to be transmitted from the engine to the manual transmission system. Pressing the clutch pedal activates this disc.
The clutch pedal: is a manual transmission part that is operated hydraulically. When manually pressed, it controls the clutch disc.
Synchronizers: Synchronizers facilitate the interaction between the collar and the gear. It makes the speed synchronized. The speed could end up being different but it prevents that from happening.
Flywheel: The flywheel is one of the major parts in manual transmission that sends torque from the engine to the clutch disc.
Gears: gears in the transmission are of different sizes, big and small. The big gears generate extra torque to slow down the speed of the vehicle. Smaller gears generate less torque, making the vehicle move faster.
Selector fork: a gear that allows the collars to move on the output shaft.
Stick shift: this manual transmission part is used for applying the gear by hand. It is connected to the gearbox.
Collar: collars are used to lock the selected gear in place and allow the torque to pass to the output shaft.

How Manual Transmission Works

The workings of this transmission system contain a set of gears along with a pair of shafts, which are the input and output shafts. The gears on the first shaft engage with those on the other shaft. The ratio between the selected gear on the input shaft and the gear engaged on the output shaft determines the overall gear ratio for that gear.

In a manual transmission system, the shift lever engages the gears. The linkages that regulate the movement of the gears along the input shaft perform the engagement. Cars with four gears or speeds have two linkages and cars with five or six speeds use three . This linkage changes by moving the shift lever left and right.

The clutch plays an important role in the working of the manual transmission, as it disconnects the engine from the input shaft of the transmission when pressed. It frees the gears on the input shaft, causing them to easily move as the engine sends torque through them.

This caused the engagement. When the clutch lever remains unpressed, we refer to the clutch as disconnected.

Once the clutch disconnects the power from the engine to the transmission, the driver easily selects the gear and releases the clutch. By releasing the clutch, the engine reengages with the input shaft, enabling the car to move at the selected gear ratio.

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