Transaxle

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by 131.181.158.29 (talk) at 01:04, 7 August 2019 (→‎Rear-engine, rear-wheel drive transaxles{{anchor|RR}}). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Csonka transaxle from 1908
Drawing of the "Alfa Transaxle" layout, with gearbox mounted in block at the rear differential; also inboard brakes to reduce unsprung mass

A transaxle is a single mechanical device which combines the functions of an automobile's transmission, axle, and differential into one integrated assembly. It can be produced in both manual and automatic versions.

Engine and drive at the same end

Transaxles are near universal in all automobile configurations that have the engine placed at the same end of the car as the driven wheels: the front-engine/front-wheel drive; rear-engine/rear-wheel drive; and mid-engine/rear-wheel drive arrangements.

Many mid- and rear-engined vehicles use a transverse engine and transaxle, similar to a front-wheel drive unit. Others use a longitudinal engine and transaxle like Ferrari's 1989 Mondial t which used a "T" arrangement with a longitudinal engine connected to a transverse transaxle. Front-wheel drive versions of modern Audis, from the A4 upwards, along with their related marques from the Volkswagen Group (which share the same automobile layout) also use a similar layout, but with the transaxle also mounted longitudinally.

Front-engine, rear-wheel drive transaxles

Front-engine, rear-wheel drive vehicles tend to have the transmission up front just after the engine, but sometimes a front engine drives a rear-mounted transaxle. This is generally done for reasons of weight distribution, and is therefore common on sports cars. Another advantage is that as the driveshaft spins at engine speed it only has to endure the torque of the engine, instead of that torque multiplied by the 1st gear ratio. This design was pioneered in the 1934 Škoda Popular, and then in the 1950 Lancia Aurelia, designed by Vittorio Jano.

Since this placement of the gearbox is unsuitable for a live axle (due to excessive unsprung mass), the rear suspension is either independent, or uses a de Dion tube (notably in Alfa Romeos). Rare exceptions to this rule were the Bugatti T46 and T50 which had a three speed gearbox on a live axle.

The Nissan GT-R and Ferrari FF (and its successors) are unusual in being all-wheel-drive cars with front-engined layouts and rear-mounted transaxles. In the Nissan, one driveshaft sends power to the transaxle (which also contains the 'center' differential) and another driveshaft sends power back along the car to the front wheels. In the Ferrari, the rear transaxle works in the conventional manner, whilst the drive to the front wheels comes from a separate gearbox at the front of the engine.

Notable Front-engine, rear-wheel drive layout vehicles with a transaxle design include:

Rear-engine, rear-wheel drive transaxles

Volkswagen and later Porsche made extensive use of transaxles in their rear (and mid) engined vehicles, including:

Four-wheel drive

All Audi cars with longitudinal engines and their 'trademark' quattro four-wheel drive (4WD) system, along with their related marques from the Volkswagen Group which share the same layout, utilise a transaxle. This is mounted immediately behind the front-mounted engine (again, longitudinally) and contains the 'gearbox' (manual, automatic, DSG, or CVT), along with both the centre differential, and the front differential and final drive unit.

Other 4WD applications include:

  • 1979-2002 Volkswagen Vanagon/Caravelle Syncro Edition - rear-engined, transaxle in the front;
  • 1984–1986 Ford RS200 – mid-engined, with the gearbox in the front;
  • 1989-2001 Mitsubishi 3000GT - front-engined, gearbox (transmission, front and centre diff) in the front;
  • 2007–on Nissan GT-R – front-engined, gearbox in the rear.

See also

References

  1. ^ "GM Heritage: The First Corvair". History.gmheritagecenter.com. Retrieved 2017-05-24.