Sometimes, the words transaxle and transmission are used interchangeably, with the latter being substituted for the former. Although they both function to transfer power from an automobile’s engine to its wheels, they are two distinct components. Typically featured in rear-wheel-drive cars, transmissions have only one job: to transfer engine power to the driveshaft using a variety of gear ratios.
In front-wheel-drive vehicles, transaxles are employed to perform the same functions as a gearbox as well as the differential’s duties, which are performed by a separate component in rear-wheel-drive vehicles. Since the transaxle is attached to the axles that drive the wheels (also known as CV axles), the correct power distribution to the wheels requires the employment of a power-splitting differential system. In essence, a transaxle is an integrated unit that combines a transmission and a differential. Read on to learn more about these drivetrain components, their primary distinctions, and how each system functions.
How Do Transaxles Work?
A transaxle is a single component that combines an axle and differential with the gear-changing capability of a gearbox. Essentially, it is a scaled-down version of the transmission frequently found in vehicles with automatic transmissions. Transaxles are found in all two-wheel-drive vehicle layouts when the engine is situated at the same end as the driving wheels. This covers both rear-wheel-drive cars with the engine behind the cockpit and front-engine, front-wheel-drive designs. The transaxle is built into the back axle of performance cars with a front engine and rear-wheel drive.
This design has the advantage of having even more front and rear weight distribution, which improves overall handling. In this instance, the lack of separate differential results in a lighter vehicle with improved performance.
The differential is housed inside the transaxle housing, which is situated parallel to the gearbox, as opposed to being located at the back of the car. Since the driveshaft does not need to be connected to the differential in order for power to be sent to the wheels, this simplifies the driveline. A transverse engine configuration, in which the engine is positioned with the crankshaft running from left to right, is common in cars with transaxles. Additionally, transaxle cars frequently weigh less than vehicles with transmissions since they have fewer drivetrain components.
How Does a Transmission Operate?
A transaxle’s transmission portion functions just like a transmission would, but instead of attaching to the back axle through the driveshaft, it houses both the differential and transmission parts. The output shaft of the transmission spins a pinion gear that is attached to the differential’s ring gear when power is supplied. Two axle shafts (or half shafts), which link the transaxle and the wheels, are used to transmit power to the wheels. Transaxles employ torque-splitting differentials to allow the axle shafts to operate at various speeds, which improves the vehicle’s ability to turn. Typically, transaxle differentials include four or more gears, two of which are coupled to the differential pinion and one to each of the axles.
What Is a Transmission?
The word transmission is sometimes used as a catch-all descriptor since it is more often used than transaxle. Power is transferred from the engine to the wheels by a gearbox, which is a set of gears. A transmission’s responsibility is to manage gear changes and transmit power to the differential through the driveshaft. There are four different transmission types: continuously variable (CVT), automatic, and semi-automatic. Most longitudinally-powered rear-wheel-drive cars feature a gearbox. With this engine configuration, a straight line is formed from the crankshaft to the driveshaft, transmission, and rear differential.
How Does a Transmission Work?
Transmissions can attach to the engine crankshaft using a torque converter, pulley system, flywheel and clutch, or all three. Typically, a transmission only has one output shaft, which the driveshaft uses to connect to the back axle. Although each type of gearbox has a unique way of working, they all regulate the speed and torque that is available to the driving wheels. The majority of gearboxes, both automatic and manual, do this using gears. However, continuously variable transmissions make use of rollers or pulleys.
Examining a manual gearbox is a straightforward technique to attempt to comprehend how a transmission functions. An output shaft connects the gearbox to the driving wheels, while an input shaft connects it to the engine. To align with the gears on the output shaft, the input shaft’s gears oscillate back and forth. A shifter & clutch pedal are used to engage these gears. The gearbox strikes a balance between torque and speed using the gear ratios. Lower ratios produce greater torque at lower RPMs, which makes it easier to start the automobile from a stop. When travelling at faster speeds, larger ratios are more frequently employed to keep the car moving and RPMs low. This implies that in first gear, you will have more wheel torque but a lower peak speed, whereas, in a gear like fifth, you will have less wheel torque but a higher top speed.
The Major Differences
The configuration of an engine is a major factor in determining whether a vehicle has a transaxle or transmission. Many of the key distinctions between these two components also exist between longitudinal (parallel) and transverse (perpendicular) engines. Transaxles are not appropriate for all vehicles; for rear-wheel-drive automobiles, the extra weight in the engine compartment might cause performance issues. Because of this, the transmission is installed behind the engine to shift more of the vehicle’s weight to the back.
This arrangement resolves the issue of reduced traction caused by lighter loads on the driving wheels. This takes us to the key distinctions between transaxles and transmissions: the former is often found on front-wheel drive (FWD) cars with a transverse engine configuration, whilst the latter is typically found on rear-wheel drive (RWD) vehicles with a longitudinal engine layout.
The driving wheels are connected to the transaxles’ two output shafts by a pair of half shafts. Direct drive shaft connections from the transmission to the rear axle are possible. Although some transaxles are capable of handling large, powerful engines, their compact design presents some engineering difficulties. Transaxles are often automatic, but they can also be manual (rarely) or CVT (becoming more popular). On the other hand, there is far more flexibility for changes and higher displacement engines in transmissions. Additionally, since transmission systems have a separate rear differential, upgrading is simple. Transmissions come in manual, automatic, CVT, and semi-automatic varieties. So, if you want a manual performance vehicle, it will probably be a vehicle with rear-wheel drive and transmission.