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A car’s drivetrain connects its engine to its wheels. Components of its drivetrain include transmission, driveshaft, axles, CV joints and wheels.
Drivers have numerous drivetrain options for their car, from front-wheel drive (FWD) to four-wheel drive (4WD). Selecting the appropriate one depends on your individual needs and preferences for how it will be used.
Transmission
Transmission is an integral component of a car’s drivetrain that connects engine power with wheels for smooth and safe motion at any speed.
Transmissions also dictate how much torque is delivered to each wheel, helping optimize fuel efficiency and protect against engine wear and tear. A good transmission also ensures that an engine stays above redline while producing maximum horsepower.
As with many components of a car, there are various forms of transmissions. While some are more intricate than others, all function by altering how much torque the engine sends through to the wheels.
Manual transmissions use a clutch pedal and lever to select and engage different gears. Semi-automatic transmissions, on the other hand, have gear changes happening automatically without having to be manually adjusted by drivers.
An automatic transmission is a modern advance for cars and trucks that uses computerized gear shifting and clutch operations to manage clutch actuation and gear changes. Commonly found on heavy-duty trucks, but also present in some cars equipped with manual transmissions.
Continuous variable transmissions (CVTs) offer seamless shifting among an extensive variety of gear ratios to optimize acceleration and fuel economy. CVTs are often found in hybrid cars that use both gasoline and electric motors to increase efficiency when needed.
At the heart of any efficient transmission lies its components: input shaft, output shaft, and clutch.
Pressing down on the clutch will disconnect both input shaft from engine and output shaft from transmission, enabling power delivery directly to wheels via output shaft which then spins with gears attached, providing power.
The clutch is also responsible for controlling fluid flows between the turbine and pump, creating more pressure, then flowing to the turbine which sends more torque through to the transmission – more torque equals faster movement of your car!
Driveshaft
A driveshaft is an integral component of car drivetrain that transmits torque from transmission to wheels. Any issues with driveshaft can affect how your car operates, potentially causing issues for its owner.
The driveshaft can be found on virtually all cars, from front-engine rear-drive and four-wheel-drive vehicles to front-engine rear-drive models with U-joint connections between it and gearbox, differential, front axles or rear axles and transfer cases.
There are two basic designs of driveshafts that differ in their construction: hotchkiss drive shaft and torque tube drive shafts.
Hotchkiss drive shafts can typically be found on older vehicles, while torque tube driveshafts have become the more popular choice among trucks and SUVs today. Torque tube drive shafts feature enclosed tubes connected by U-joints to both transmission and differential components of an automobile’s drive train.
U-joints are essential components of driveshafts, serving as flexible pivot points that enable variable angles while torque transfer takes place. CV joints (constant-velocity joints) also play a vital role, as they allow bendability without impacting drive wheels rotation speed.
Telescoping driveshafts are more advanced designs than U-joints in that they extend and retract as the suspension articulates, providing for maximum power transfer between engine and wheels. Telescoping driveshafts are commonly found in racing applications as they enable maximum transfer between power source and wheels.
Telescoping driveshafts may be very effective, yet their design can be complex and expensive. Furthermore, binding between transmission and axles may lead to less active suspension systems.
If your vehicle displays any of these symptoms, it would be prudent to have it serviced immediately. This is especially important if the drive shaft is making noises or you experience handling issues with your car.
Common telltale signs of driveshaft issues include clunking or popping sounds that indicate wear on U-joint bearings; in such instances it may also be necessary to replace the driveshaft itself due to extensive wear.
Differential
Differentials are an integral component of any vehicle’s drivetrain – the system which transmits power from its source to each wheel. A differential allows various speeds for its wheels to spin at, helping make corners more smoothly and efficiently.
Based on its type, differentials may be situated either between the front or rear wheels (front differential), between front and rear tires (rear differential), or all four tires combined (four-wheel drive). Differentials also help decrease traction when going down steep driveways, helping improve performance overall.
There are three major types of differentials: open, limited-slip and locking. Each differential works differently and has their own set of advantages and disadvantages.
Limited-slip differentials use gears to transfer engine torque, and adjust as traction improves and resistance declines, providing smooth driving performance on higher-end vehicles requiring advanced driving skills.
Some limited-slip differentials use a mechanical clutch, which restricts slip by shifting torque to wheels with greater traction, however this method can be costly and inefficient.
Installing a torque-sensing differential may also provide another solution, by sensing engine torque and redirecting it towards wheels that offer more grip. This system is ideal for drivers who wish to control their speed but do not wish to deal with clutch or mechanical limited-slip differential issues.
No matter the differential you opt for – open, limited slip, or locking – it’s essential to remember that these components are designed to withstand high levels of pressure and require strong materials – they no longer use straws and milk bottle caps! Therefore, it is imperative that they are kept properly lubricated.
Faulty differentials can cause vibration and binding during turns, potentially damaging wheels and drivetrain. Any potential issues should be identified immediately so any correction can take place as soon as possible. It’s advisable to have your differential regularly inspected so any issues can be addressed as quickly as possible.
Clutch
The clutch is an integral component of car drivetrain that connects engine power to driving wheels. It does this by enabling gear shifts for smooth transition from one speed to the next.
A clutch is composed of multiple parts that work together to connect and disconnect an engine with its driving wheels, including a flywheel, pressure plate, disc, throw-out bearing and release system. A foot pedal controls these parts; additional links control springs, leavers and throw-out bearings of the clutch itself.
When the clutch pedal is not depressed, a diaphragm spring pushes a pressure plate against a flywheel to create frictional force between them and causes clamping pressure on the pressure plate to ease as its force is relieved by a release fork which moves a release bearing against its centre to ease clamping pressure on it and thus release clamping pressure off of it.
Reduced pressure allows the clutch disc to separate from the flywheel. The clutch disc is a small metal ring that transfers engine torque through to gear shaft through clutch plate, featuring friction linings similar to brake pads for smooth engagement; however, they don’t fare well under high temperatures.
There are various types of clutches on the market today, each made out of different materials such as carbon and ceramics, while others may use Kevlar or organic compounds.
These materials are combined into multiple friction plates that can withstand considerable torque input. Each friction plate is slightly larger than its counterpart to provide more surface area for friction to grip against and generate higher-performing clutches that are more robust.
The driven member (or friction plate) runs on a splined input shaft connecting pressure plate and flywheel, transmitting power from one surface to the other for transmission to gearboxes with friction linings similar to brake linings on both surfaces.
As soon as a clutch is engaged, a diaphragm spring presses the clutch plate against the flywheel to create friction. When released, either cable or hydraulic piston pushes a release fork against the center of diaphragm which reduces clamping force of pressure plate and allows clutch disc to disengage from flywheel allowing engine and gearbox to spin at equal rates.