adminAUTOMOBILE FRONT AXLE DRIVE SYSTEM
A front axle drive system also known as a front wheel (FWD) system is a drivetrain system that transmits power from the engine to the front wheels to propel the vehicle forward and to provide traction and stability.
The front axle drive system consists of; transaxle (or transmission and differential), front axle shaft, constant velocity (CV) joints or U-joints, hub assembly and front wheel bearings.
The transaxle is a critical component of the front wheel drive (FWD) system. It is a combination of a transmission and differential, in one housing. The transaxles primary function are, transmit power from the engine to the front wheels, change gear ratios to optimize power delivery and fuel efficiency and distribute (i.e. differential) power to the front wheels, allowing them to rotate at different speeds.
The front axle shaft connects the transaxle to the front wheels and transmits power from transaxle to the front wheels. The front axle shafts primary function is to transmit power from the front wheels, support the front wheels and provide a smooth ride.
The constant velocity or universal joints connects the front axle shaft to the front wheels and allows for smooth power transmission while accommodating the up and down motion of the front wheels. The constant velocity or the universal joints primary functions are transmit power from the front axle shaft to the front wheel and accommodate the up and down motion of the front wheels.
The hub assembly connects the front wheel to the front axle shaft and provides a smooth ride. The hub assembly primary functions are support the front wheels, provide a smooth ride and transmit power from the front axle shaft to the front wheels.
The front wheel bearing supports the front wheels and provides a smooth ride. The front wheel bearing primary functions are support the front wheel, provide a smooth ride and reduce friction and heat generation.
There are three main variant of the front axle drive system used in vehicles and they are; transaxle front axle drive, front wheel drive (FWD) with a separate differential, and all-wheel drive (AWD) front axle drive.
Transaxle front axle drive system uses a transaxle which combines the transmission and differential into a single unit. The transaxle is connected to the front wheels through a driveshaft and a hub assembly. Examples include; Honda Civic, Toyota Corolla, Volkswagen Golf etc.
Front wheel drive (FWD) system uses a separate differential which is connected to the front wheels through a driveshaft and a hub assembly. Examples include; Ford Focus, Chevrolet Cruze, Hyundai Elantra etc.
All-wheel drive (AWD) front axle drive system uses an all-wheel drive system which sends power to all four wheels. The front axle drive system is connected to the rear axle drive system through a transfer case. Examples include; Subaru Impreza, Audi A4 Quattro, Volvo S60 AWD etc.
The advantages of a front axle drive system are; front wheel drive vehicles tend to have better traction and stability. Front wheel drive vehicles are generally lighter in weight compared to rear wheel drive vehicles. Front wheel drive vehicles systems are generally simpler in design compared to rear wheel drive vehicle systems. Front wheel drive vehicles often have more interior space compared to rear-wheel drive vehicles.
The disadvantages of front wheel axle drive system are; front wheel drive vehicles can struggle with high power engines as the front wheels can become overwhelmed with torque. Front wheel drive vehicles can exhibit under steer which is loss of traction at the front wheels during cornering. Front wheel drive vehicles are not suitable for extreme off-road use as they can struggle with low traction conditions.
The application of front axle drive systems are as follows; front wheel drive vehicles are commonly used in passenger cars, especially in compact and mid-size cars. Front wheel drive is often used in small SUVs and crossover vehicles which are designed for on-road driving. Front wheel drive is often used in hybrid and electric vehicles so as to improve fuel efficiency and reduce emissions.
The future of front axle drive systems depends on the advances and development of the following technologies; the use of advanced materials such as carbon fiber and aluminum to reduce the weight of the front axle drive system, hence improving their strength and durability. Front axle drive systems are expected to become more efficient with improvements in design and technology of vital parts and components using new materials and manufacturing techniques. The increase in the popularity of AWD and 4WD systems may lead to a decline in the use of front axle drive systems only in the future.
SOURCES:
- Automotive technology: Principles and systems by Keith Owen and Tom Denton.
- Front wheel drive vehicle design by David A. Stephenson.
- Automotive engineering: Powertrain systems by R.R Roberts and J.H Edwards.
- Vehicle dynamics and control by Rajesh Rajamani.
- Fundamentals of vehicle dynamics by Massimo Guiggiani.
