Transaxle

from Wikipedia, the free encyclopedia
Front engine ...
... and rear transmission

Transaxle ( English transmission = gearbox and axle = axle) is the designation for a drive design in vehicles in which the engine is at the front, but the gearbox is located on the driven rear axle. In this form of rear-wheel drive , the gearbox, differential and final drive are housed in a common housing and connected to the motor by a shaft, the transaxle shaft.

properties

In contrast to the widespread design of vehicles with front-engine and rear-wheel drive , in which the engine and gearbox are in the front (usually as a block engine ) and drive the rear axle via a cardan shaft, in the transaxle design the gearbox and usually also the clutch with the Rear axle differential and the final drive blocked to form a unit. A jointless drive shaft that rotates at engine speed in a tube between the engine and the gearbox transmits the drive power. A simpler construction is the construction without a connecting pipe, but then with a cardan shaft. In rare cases the clutch is attached to the front of the engine.

The four-wheel drive Ford RS 200 mid - engine vehicle for rally use had the gearbox on the front axle differential, i.e. an inverted transaxle construction.

The Nissan GT-R is another exception. As is usual with the transaxle design, the engine is in the front and the gearbox is in the rear. However, a second drive shaft leads from the transmission to the front axle. So here an all-wheel drive was combined with a transaxle. Mowag also uses this principle in the Mowag Duro off-road vehicle .

In the 2011 Ferrari FF , the V12 engine sits behind the front axle, a 7-speed dual clutch transmission sits on the rear axle and a 2-speed gearbox sits on a second crankshaft output on the front of the engine, which works in the first two forward gears and in the Reverse gear implemented an all-wheel drive without a center differential (called "4RM").

Advantages and disadvantages

Cut open transaxle housing of a Csonka : on the left the gearbox, on the right the bevel gears of the final drive

As with the mid-engine design, the aim of the transaxle drive is to achieve a balanced weight distribution. Vehicles with front-wheel drive are almost always front- heavy , those with front-engine and rear-wheel drive are mostly front- heavy , and cars with rear-engine are almost always rear-heavy. Unlike a mid-engine, the transaxle drive can also be used for sedans, and the vehicle has a higher moment of inertia around the vertical axis, which counteracts the tendency to skid. The resulting higher weight on the rear axle of the mostly rear-wheel-drive sports vehicles also enables greater power to be transmitted to the tires, which, for example, also increases safety when driving in snow. The separation of the engine and transmission also means that the transmission is not additionally thermally stressed by the waste heat from the engine. The transaxle shaft can be built lighter because it does not have to transmit as high a torque as the cardan shaft with conventional rear-wheel drive. The clutch is usually not located on the engine, but directly in front of the transmission. This facilitates the synchronization in the transmission, as the transaxle shaft does not have to be accelerated or braked when shifting.

Another plus point is the increased safety in the event of a frontal collision, as forces are also introduced and reduced in the rear area of ​​the body via the rigid transaxle shaft and the suspension of the rear axle.

Theoretically, one of the disadvantages of the transaxle design is the wear-prone and noisy storage of the transaxle shaft, for example in the Alfa Romeo models of the Alfetta series. However, this disadvantage can be largely compensated for by means of flexible disks . In sedans, the gearbox is placed in front of the rear axle (under the rear bench seat) so as not to restrict the trunk too much. In sports and racing cars, with the gearbox at the rear, the center of gravity can be shifted further back because the trunk does not matter. In the case of manual transmissions, the shift linkage must be guided to the rear; the switching precision can suffer. Nevertheless, the advantages predominate, especially with powerful vehicles.

Examples of transaxle vehicles

Historic vehicles

Current vehicles

Transaxle vehicles with special designs

  • Nissan GT-R , front engine, gearbox on the rear axle, all-wheel drive
  • Mowag Duro , front engine, gearbox on the rear axle, all-wheel drive
  • Ford RS 200 , mid-engine, separate gearbox on the front axle, all-wheel drive
  • Ferrari FF , front mid-engine, 7-speed gearbox on the rear axle, 2-speed gearbox on the front axle

Individual evidence

  1. ↑ 1930 Bugatti T46 “Petit Royale” Sports Saloon by Freestone & Webb . RM Auctions. Archived from the original on October 15, 2011. Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved December 11, 2012.  @1@ 2Template: Webachiv / IABot / www.rmauctions.com
  2. ↑ Škoda 420 Popular (PDF; 332 KB) Autostadt . Retrieved December 11, 2012.

literature

  • Peter Gerigk, Detlev Bruhn, Dietmar Danner: Automotive engineering. 3rd edition, Westermann Schulbuchverlag GmbH, Braunschweig, 2000, ISBN 3-14-221500-X
  • Max Bohner, Richard Fischer, Rolf Gscheidle: Expertise in automotive technology. 27th edition, Verlag Europa-Lehrmittel, Haan-Gruiten, 2001, ISBN 3-8085-2067-1
  • Jan Drummans: The car and its technology. 1st edition, Motorbuchverlag, Stuttgart, 1992, ISBN 3-613-01288-X
  • Harald Naunheimer, Bernd Bertsche, Gisbert Lechner: Vehicle transmissions . 2nd edition, Springer Verlag, Berlin, 2007, ISBN 978-3-540-30625-2

See also