Whether you’re a car enthusiast or just someone who wants to better understand your vehicle, knowing the key terms associated with gearboxes can help you communicate effectively with your mechanic and stay informed about potential repairs. While we work hard to ensure we are transparent and accessible with our repairs and communication, understanding what some key terms mean can help set you off on a stronger foot. Here, we’ve put together a glossary of essential gearbox terms every car owner should be familiar with.
1. Transmission
Transmission is another term for the gearbox, which is the system in your car that transfers power from the engine to the wheels. It allows the vehicle to shift gears and control speed and torque. There are two main types of transmissions, automatic and manual, however there are other hybrid and specialised transmissions available.
2. Gear Ratio
A gear ratio refers to the relationship between the number of teeth on two meshing gears. It dictates how much torque is transmitted to the wheels. Lower gear ratios offer more torque and better acceleration, while higher gear ratios help with fuel efficiency at higher speeds.
3. Clutch
In a manual gearbox, the clutch is a key component that allows the driver to engage or disengage the engine from the transmission. When the clutch is pressed, it disconnects the engine from the drivetrain, enabling the driver to change gears.
4. Torque Converter
In an automatic transmission, the torque converter takes the place of a manual gearbox’s clutch. It transfers power from the engine to the transmission by using fluid dynamics to manage the gear changes, allowing the car to move without the driver needing to manually shift gears.
5. Synchroniser
A synchroniser, or synchro, is found in manual transmissions and helps ensure smooth gear shifts by matching the speed of the input shaft to the speed of the gear being engaged. This prevents grinding noises and makes gear shifting smoother.
6. Planetary Gear Set
A key component in many automatic transmissions, the planetary gear set consists of a central “sun” gear, outer “planet” gears, and a “ring” gear. This arrangement allows the transmission to provide multiple gear ratios in a compact design, contributing to the smooth operation of automatic gearboxes.
7. Shift Solenoid
In an automatic transmission, shift solenoids control the flow of transmission fluid and determine when the vehicle should change gears. These solenoids receive signals from the vehicle’s computer system to ensure the gearbox operates smoothly and efficiently.
8. Valve Body
The valve body is the brain of the automatic transmission. It controls the flow of transmission fluid to different valves, directing the appropriate gear changes based on speed, engine load, and other driving conditions.
9. Gear Selector
The gear selector is the lever or dial in your car that allows you to manually select gears in both automatic and manual transmissions. In manual vehicles, this will usually be 1-5, with higher numbers available for cars with more gears. In automatic vehicles, it’s typically marked with letters like “P” for Park, “R” for Reverse, “N” for Neutral, and “D” for Drive.
10. Flywheel
The flywheel is a rotating mechanical component connected to the engine and transmission. It stores rotational energy and helps to smooth out the power delivered by the engine, allowing for consistent performance during gear shifts, particularly in manual vehicles.
11. Slip
Slip occurs when the transmission’s clutch or torque converter isn’t fully engaging, causing a loss of power. This can lead to sluggish acceleration, increased fuel consumption, and potential long-term damage to the gearbox.
12. CVT (Continuously Variable Transmission)
A CVT is a type of automatic transmission that doesn’t use traditional gears. Instead, it uses a system of belts and pulleys to provide a seamless range of gear ratios, which can improve fuel efficiency and deliver a smoother driving experience.
13. Drivetrain
The drivetrain is the collection of components that deliver power to the car’s wheels. It includes the gearbox, driveshafts, axles and differential. The drivetrain plays a critical role in ensuring the vehicle moves efficiently and responds to driver input.
14. Overdrive
Overdrive is a feature in some transmissions that allows the vehicle to cruise at high speeds with lower engine RPMs, reducing fuel consumption. It is typically engaged when driving at highway speeds to improve fuel efficiency and reduce wear on the engine.
15. Final Drive
The final drive is the last stage of the drivetrain that delivers power to the wheels. It typically involves a set of gears, such as the differential, which adjusts the torque and speed to match the driving conditions and terrain.
16. Input Shaft
The input shaft is the component in the transmission that receives power directly from the engine. It is the first point of contact in the gearbox and works with other components to transfer power to the wheels.
17. Output Shaft
The output shaft is the shaft that transmits the power from the transmission to the rest of the drivetrain, ultimately powering the wheels. It works in tandem with the input shaft to ensure the proper transfer of power.
18 Transmission Fluid
Transmission fluid lubricates and cools the internal components of the gearbox, reducing friction and wear. It is especially important in automatic transmissions, as it also helps transmit hydraulic pressure for gear shifts. Keeping an eye on your transmission fluid levels is essential for maintaining a healthy gearbox.
19. Shift Pattern
A shift pattern refers to the layout of the gears in a manual transmission. It determines the sequence in which you shift between gears, often represented as a diagram near the gear lever (e.g., “H-pattern” for most manual cars).
Understanding these gearbox terms can help you make more informed decisions about your vehicle’s maintenance and repairs. Whether you’re talking with your mechanic or trying to diagnose a problem, knowing the language of the gearbox will put you in the driver’s seat when it comes to car care.