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What is the gearbox transmission/what does it do?

The gear box transmission is one of the most important parts of a vehicle. Whilst the engine is the part of a vehicle that provides the power to drive it, it would be useless without the gear box transmission, which transfers the power from the engine to the wheels, thus enabling the vehicle to move.

Getting into the details of the gearbox transmission

There are two main types of gear box transmissions. The first is a manual transmission, and the second is an automatic transmission. Whilst these both have the same purpose, they are operated in different ways with the automatic transmission controlled by an on-board computer system and the manual transmission controlled by the driver. There are other gear box transmissions such as the Tiptronic and Selespeed transmissions that use a combination of manual and automatic functions to operate the gears.

In most standard manual gear box transmissions the driver will select the gear by moving the gear stick in the correct position and will feel the gear click in to place. The gear change system usually has a rod attached to the gear handle. This in turn is attached to the brake pedal arm. The linkage also connects to the firewall via a cable. When the driver moves the gear stick the linkage system pushes or pulls on the cable and a transmission linkage also does the same thing. Together they change the gear. Some gear linkage systems bypass the use for the gear rod altogether and instead use the movement of the gear handle to create the pressure on the cable and change gears.

The amount of linkages in a gear box transmission will be determined by the amount of gears on the gear box. In a vehicle with four gears two linkages will be used, whereas in a five or six gear transmission there are three linkages. These linkages each control two gears.

To engage a gear in a manual gear box transmission, the driver pushes the clutch. This causes the clutch pressure plate to and clutch disc to pull away from the flywheel, disconnecting the engine from the transmission system in order to change a gear. In an automatic gear box transmission, a similar process occurs. However, unlike a manual transmission, the automatic transmission does not use a clutch and instead relies on a torque converter to disconnect the engine from the transmission.

An automatic gear box transmission also differs from the manual transmission in the way that the gears are positioned. In a manual transmission, the gears are arranged on two parallel shafts, whereas on an automatic they are arranged on one concentric shaft with gears arranged in a ‘planetary’ arrangement. Rather than being controlled by the physical operation of a driver, the automatic transmission is controlled by a hydraulic system which decides which gears in the planetary arrangement are operated and when.

What if something goes wrong with the gearbox transmission?

Damage to the gear box transmission may first be noticed if the vehicle is slow to respond when put in drive to begin your journey. This suggests that there is an issue with the transmission, possibly from the gear linkages or other issue. Another thing to look out for is clunking or humming noise from the gear box. This may or may not be associated with difficulty in changing gears, particularly in to first and second gear and should be checked immediately to minimise damage. You may also notice a transmission fluid leak under the vehicle. This fluid is red and has a sweet smell so is easily noticed.