Here in Oregon, we experience a variety of weather conditions , including lots of rain and snow. These variable weather conditions can make driving challenging and sometimes even dangerous without the right equipment. When shopping for your next car, weather and safety are the perfection reasons to consider an all-wheel drive vehicle.
This clutch mechanism is electronically controlled, allowing the SH-AWD system to alter torque delivery to the rear wheels at all times.
One of our salespeople will contact you shortly to confirm the time and date. Morning Afternoon Evening. Check Availability Love the vehicle so much you would like to check availability? Get More Info. Buy Online Buy Online. Schedule Test Drive. Filter Results Close. Saved Vehicles Close. Audi's all wheel drive system quattro was introduced in on the Audi Quattro.
Audi's parent company Volkswagen Group has been developing four-wheel drive systems almost since its inception during the Second World War. The ATTS was able to distribute torque across the front drive wheels in order to reduce understeer in cornering, and provide more neutral handling for the front-wheel driven car. This improved version provided earlier SH-AWD intervention first gear vs second [10] and more precise use of the rear differential electromagnetic clutch system to provide an improved limited-slip differential function.
The newly introduced Acura ZDX four-door sports coupe maintains a mechanically similar fixed 1. This would be the first time a six-speed automatic transmission would be mated to SH-AWD, as well as being the first six-speed automatic transmission introduced in either the Acura or Honda line up.
In December , the Acura RL was announced [18] with a second Mid Model Change, featuring, among other things, a six-speed automatic tranmission. The engines are mated to a front wheel drive transaxle. There is no center differential. The transaxle is bolted to torque transfer unit that spins a center drive shaft that powers the rear differential unit. The rear differential is a T-shaped device. Power coming from the engine is transferred via a central hypoid gear that delivers power to each rear axle.
Power to the each axle is modulated by identical planetary gear sets and electromagnetic clutch packs which can vary incoming power side to side [2]. Acura RL's exclusively contain a third planetary gear set and clutch pack that are packaged into a so called "Acceleration Device", which is bolted in front of one the rear differential unit [2].
As of early , SH-AWD has been implemented by Acura in two functionally similar, but mechanically different configurations, with and without Acceleration Device.
If that was the case, when you are making a right turn, your left rear wheel will spin much faster than the front wheels. Whenever the clutch is engaged, the planetary gear set will fall into the case that the input is trying to drive something the output which is spinning faster. This means the engine is providing a braking effect to the rear wheel, which will cause loss of control and is not what we want. So if there is no build-in rotation difference, the rear wheel is unable to get any power during cornering, not to mention the torque vectoring.
Is there any chance that the rear wheel spins more than 1. The answer is yes. Take the MDX as an example, its rear track width is 1. Therefore, if your turning radius is less than First, the above is just a theoretical computation, there are two factors that help to alleviate the above issue. Below illustration shows the Acceleration Device installed in front of the rear drive unit. The reason why it needs the 5. By providing a higher overdrive ratio, it is less possible that the rear wheel will use up the allowance provided by the overdrive ratio.
However, although not taking the full workload, the rear wheel clutch still need to take care of a portion of the energy. Therefore a larger overdrive ratio means higher wear and heat in the clutch pack. So under normal driving conditions, the Acceleration Device will shift to another gear that uses a lower overdrive ratio to decrease the wear and heat.
The only disadvantage of this design is: there is a time lag for the Acceleration Device to shift between the two gears, so it may not work as fast as you wish under some special driving situations.
In the SH-AWD system, for each rear wheel if you replace the planetary gear set plus the clutch with a single wet-type clutch pack, you will get the VTM-4 system of course some components and also the ECU are different, however the mechanical schema will be like this. See the below illustration. This changes the way how the rear wheel drive unit work fundamentally. It works in the same way as the GKN Twinster.
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