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Print 58 comment(s) - last by Skywalker123.. on Jun 11 at 4:08 AM

Special fluid would only allow the driver to choose the correct gear

Walk into a room full of automotive enthusiasts and ask about manual transmissions and you'll likely get mixed responses. Sports car purists think a row-your-own, manual gearbox is the only way to go. However, many feel that the new semi-automatic gearboxes where shifts are made by clicking paddles behind the steering wheel are superior. Based solely on how quickly gear changes can be made, fans of the semi-automatic gearbox have a point.
 
Efficiency and speed aside, many sports car fans won't buy a car without a manual transmission. While BMW sells more cars with automatic or SMG gearboxes, a patent has surfaced that shows the traditional manual transmission still has a place with the BMW brand. The patent shows that BMW is considering a future with manual transmissions that have more than the normal six forward gears common today.
 
Many automatic transmissions are capable of better fuel efficiency than a manual transmission simply due to the fact that some have more forward gears with high seventh or even eight ratios to cut fuel consumption.
 
BMW's patent describes the problem was simply adding more gears to the current six speed manual transmission. The patent reads, "an 8 speed manual transmission would need four shift gates for the 8 gears alone." The problem with adding more gates is that it becomes difficult for the driver to shift gears and the potential for accidentally shifting into a lower gear and damaging the engine by over-rev grows.
 
BMW's solution of adding more gates and the growing complexity for drivers is both insane, and incredibly smart. BMW wants to design a manual transmission that will only allow the driver to shift into the correct gear. Anyone that's accidentally grabbed second on a 4 to 3 shift at speed will appreciate that innovation.
 
BMWs innovation creates shift gates that are surrounded by a magnetorheologic or electrorheologic fluid. That is a complicated way of saying that the fluid would prevent any improper shift when a voltage is applied to change viscosity of the fluid, therefore physically blocking any gear but the correct gear for downshift. The technology could be used on manual transmissions with a clutch pedal or without.
 
BMW sees an interesting potential by creating a shift-by-wire transmission where you can shift gears with a lever without having use a clutch pedal. This would be sort of a combination of an automated SMG and a traditional manual transmission. There is no indication of when this technology might come to market at this time, but it sounds like a very good idea.
 
Porsche already has a seven-speed manual transmission available in the 2012 911.

Source: E90 Post



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RE: Shifter design
By FITCamaro on 6/7/2012 11:38:23 AM , Rating: 2
If you shift from second to first instead of third and release the clutch, it doesn't matter if you have a rev limiter. The engine at that point is mechanically linked to the wheels in that gear and is going to spin however fast the wheels and that gear dictate.

While most will react and push the clutch in quickly, that doesn't guarantee that you didn't damage anything in that second or two. Assuming the motor doesn't just blow up. I've seen what happens to an engine when its shifted into the wrong gear at speed. Saw an LS6 from a race shop Corvette that one of the mechanics was testing on the road course and put a piston out the side of the block from a wrong shift. 10-15k rpm can do very bad things to a motor not built for it.


RE: Shifter design
By Reclaimer77 on 6/7/2012 11:49:40 AM , Rating: 1
Yeah I had a brain fart on that one lol. I dunno, I've been driving manuals for like 15 years and have never blown a shift that bad.

HOWEVER, side note, it's really cool that among the flood of boring EV and hybrid articles, DT finally has something about an ICE car. A 7 speed to boot!


RE: Shifter design
By DiscoWade on 6/7/2012 1:00:35 PM , Rating: 2
My 2004 350Z 6-speed manual makes it very difficult if not impossible to choose a gear that will over-rev the engine. I never have tried to force, but I do know that it feels like there is a lock on 1st or 2nd gear when going 55 MPH. It really is a good solution: prevent the driver from choosing a gear that will damage the engine.


RE: Shifter design
By ATX22 on 6/7/2012 1:24:18 PM , Rating: 3
The 5-speed in my GMC truck is basically the same. Trying to shift in a gear that is way too low while going too fast would take A LOT of work. It doesn't grind or kill the engine, it just makes a whirring noise (probably the synchronizers) and refuses to drop into gear.... I guess it can still be FORCED into gear, but that would be deliberate damage at that point.

A 7-speed wouldn't be hard to learn at all... been wanting an extra gear on the dodge... 6 gears just aren't enough when you're on the highway in a diesel pulling no load.


RE: Shifter design
By drycrust3 on 6/7/2012 5:52:49 PM , Rating: 2
We have Scania buses at my depot, and they have an automatic transmission (that does at least 5 gear changes to get to 50 km/hr), and according to a Scania mechanic, the gearbox used is exactly the same gearbox as used in the "manual" transmission trucks. He said the only difference was the truck had a gear lever while we have three buttons (and the appropriate control-interface differences).
My guess is the gear lever arrangement on this car could be just about anything, the "gear lever" being just an indicator of which gear to use. Why not, for example, just have an "up or down" gear lever, leaving the actual ratio selected up to the gearbox?


RE: Shifter design
By Calin on 6/8/2012 2:56:58 AM , Rating: 2
I suppose the 7th gear is only for low rpm at high speed, the 6th gear would be the highest in use during "sporty" driving


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