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A Gearbox Is a Car Essential, What Are the Functions of a Gear Box?

Updated on December 18, 2017
Brianlnathans profile image

I am a car enthusiast, I like to know how cars function, why they function the way they do and I want to teach you how they function

Gear box functions, parts and components of a gear box, transmission box,


A gearbox which is also sometimes called a transmission box, is a device used especially to help a car manage the terrain of a road. It basically changes the torque depending on the terrain of the land in which the car is moving. An automotive will require a very low torque when it is moving on flat ground even though it may be moving at high speeds. You will find that a car will need a high torque when climbing a hill or when it is just starting considering that the vehicle is also moving at low speed. Low torque when the vehicle is moving on flat ground is associated with the momentum of the vehicle which is also as a result of a high velocity. So basically the gearbox or transmission box changes the torque depending on the condition of the road. Change in the torque is also brought about by the load the vehicle is carrying as we shall discover later. Considering also that the gearbox is also the second element of the power train in a vehicle. Let us discuss more on the functions of the gear box. Depending on the terrain of the road and the weight of the load it is carrying, the gearbox provides the most suitable torque for the vehicle as it operates in these conditions. The transmission box does this change of torque by changing the ratio of the gears (gear ratio).The gearbox, I would say controls the entire transmission process of the vehicle. It also enables the car to be driven backward by the gearbox being shifted into reverse. The gearbox can be shifted into neutral which is done when starting the engine of the automobile. The increase or decrease of the torque of the vehicle is determined by the speed of the vehicle.

Other functions of a gearbox

The gearbox can be compared to the electrical power transformer which keeps stepping up and down the voltage and controlling the flowing current. This is the same with torque and rotations per minute of the vehicle wheels. These changes in torque which are affected by speed are based on the driver’s need, in that for example when the driver wants to park the vehicle, he will need a high torque which will require him to reduce the speed of the vehicle as he gets close to the parking spot. This means that at a higher speed, the created torque is going to be reduced. Ever wondered why we can only effectively ride bicycle on a hill using the first gear? This is because this is the gear that can have a low speed and yet a high toque hence enabling the rider to move up hill with less energy, less speed but yet be able to take on the steep.

Functions of a gearbox

The gearbox occasionally will contain two or more gears. Gears are concerned with transmitting power from one part of a vehicle to another. Like it is commonly known that gears in a bicycle transmit power from the pedals to the back wheel, in a vehicle, there is a transmission of power from the crankshaft which is the rotating axle that takes power from the engine to the drive shaft which runs under the car powering the wheels. Precisely looking at the work and functions of a gearbox, we can say that it changes the low torque which is associated with high speed to high torque which is associated with low speed or vice versa. The gear head runs on a chain with the gear ratio of 1:1 which tentatively is used for reducing the transfer of motor vibrations to the load of the vehicle. The gear head also reduces the inertia of the load that is being carried on the vehicle. The gearbox has a variety of gears which can also be called gear ratios. It is made with the ability to change the gear ratios as speed changes hence controlling torque. Output of the gearbox is via the driveshaft to one or more differentials driving the wheels. Basically the differentials allow the wheel at either end of the axle to turn at different velocities which is essential to provide wheel slippage. Though it should be noted that the change of torque can also be done by other means except the gearbox when we put mechanisms like torque converters into consideration. There are also power transformations through the diesel-electric transmission and the hydraulic drive system. There is also hybrid transmission where several of these systems are put to work together. Another function of the transmission box is to increase the rpm (rotations per minute) of the main shaft of the gear box in fifth gear more than the engine’s rpm.

This is the power of a high torque. It can be noted that newer vehicles have several gears now up to 6 gears to enable the car to operate at a higher frequency, choosing the appropriate gear for the terrain hence increasing engine efficiency. Interestingly, the gearbox will also keep the car stationary even if the engine is running. Without a gearbox this would be impossible. Imagine a car with one gear, this vehicle will be limited in efficiency at different terrains and situations hence making it hard to drive effectively. The gearbox is as important as an electricity transmission transformer. It makes torque appropriate for the condition by the driver increasing or reducing speed depending on the need.

© 2017 Brian L Nathans


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