Ya tap the down button two..three,,hell four times and it goes to that gear and the computer doesn't let the clutch out til your going slow enough...I hope that's clear...
It's not like you have a mechanical connection...fly by wire and all...the computer does the shifting and the thinking when necessary. I agreed that by definition the transmission must slide thru each gear,,it just doesn't engage it.
You won't even take yes for an answer,you just want to argue.
To achieve anything, you must be prepared to dabble on the boundary of disaster.”
Sir Stirling Moss
bhallg2k wrote:I might be making this up, but I think the transmission of the McLaren MP4-12C is configured for shifts just like that.
I believe at one point there were fully automatic gearboxes that knew where they were on the track to help determine what might be required.
What value would position knowledge be to the system? Wouldn't the normal speed, brake, rpm, and torque request (pedal position) be enough?
Brian
I believe you may have let your trademark incredulity run a little too rampant this time, because it seems as though you've made an assertion and then immediately questioned the wisdom behind it.
bhallg2k wrote:I believe you may have let your trademark incredulity run a little too rampant this time, because it seems as though you've made an assertion and then immediately questioned the wisdom behind it.
So why the requirement for track position? I remember that they baselined each lap at the timing beacon. Do you see any value from such programing?
While I can´t speak with any authority for F1, in other top level racing series, position information is/was mainly used to control differential locking rates, for
different parts of the track/corner.
It can be also used to "override" a normal upshift strategy, which would be based on rpm (automatic upshift @ xxxx rpm), because sometimes it is more beneficial to just run a short time/distance into the limiter, then to upshift for 20 meters and then need to downshift one gear more again before the next corner.
Any half decent GT3 car(let alone higher classes) with an AGS (assisted gear shift) system would be able to fully automatic up and downshift based on rpm upshift and rpm/road speed match downshift today - if it was permitted by the rules.
Some cars used it in the past, but these automated shift strategies got banned, so today it´s similar to the current situation in F1, where the driver needs to initiate each up/downshift, all what the ECU/gearbox controller can do, is ignore the shift command, if it would lead to an engine over-rev, in this case the driver will need another downshift request.(pull/press the paddle again)
Before, automated downshifting was banned, the driver could/would preselect the gear in which he wanted to take the corner, and then just start braking.
When the optimum point for a downshift was reached (road speed/engine rpm match), the gearbox controller would initiate the downshift automatically.
It would continue until the preselected gear was reached, so the driver could just concentrate on his braking and turn in, and did not need to bother with the correct downshift timing.
hardingfv32 wrote:So why the requirement for track position? I remember that they baselined each lap at the timing beacon. Do you see any value from such programing?
I have no idea, chief. You yourself introduced that concept into the discussion, so you tell me.
gato azul wrote:While I can´t speak with any authority for F1, in other top level racing series, position information is/was mainly used to control differential locking rates, for
different parts of the track/corner.
I think it was 1981 when we drew up a fully automatic 25 speed F1 powertrain based on bevel epicyclic gears, that could be operated from the pits if needed.
With that number of gears it was as close to a CVT as you could get and the rev drops on the shifts made it capable with the electronicaly controlled diff for fully automatic dynamic control in real time.
Patrick Head was working up the Williams CVT at this time.(a wrong avenue)
The FIA structured the regulations to prevent sensible investment in development and in the early 90's they set the number of gears at 7 with manualy commanded upshifts.
To give the public the idea that manual skill was being returned, they then decided on sequential operation followed by outlawing automatic downshifts.
With the introduction of KERS came bigger problems. Trying to balance braking, gear shifting and energy recovery from overrun has become difficult.
This year 2012 there are small regulations to confine the gearbox operation and allow a better balance to be made.
In 2014 there will be 8 gears to help spread the load and reduce the unbalancing of the cars caused by sudden regeneration, the torque spike from the ancient layshaft gearboxes and the unbalanced results of worn friction to heat brakes.
A combination thought up to continue with all the ancient engineering.
High Downforce will then be absolutely essential to mask all these compromises. Any attempt to return to manual gearboxes will then be futile. I discussed the maximum number of gears a driver could use with Garry Anderson of Jordan at some length in the late 80's. The number was accepted by the FIA as 7. Any more and it becomes a hopeless task to shift manualy.
High downforce and 8 gears with shifts modified to help KERS and Kers itself neutered in preference to aero will be the end of F1 IMO.
Gearbox discussion stalled for a while, but now I have something to talk about... Here is interesting explanation of radio message, which Webber heard during the formation lap just before the start of 2012 European GP. He was told to perform 7th gear synchronization.
There are rotary position sensors on the gear selector barrel that correlate voltage to selected gear number. With heat and mechanical tolerance, they can be slightly misaligned, so they can do a quick recalibration from the cockpit by engaging 7th gear and telling the gearbox control MCU that the box is physically in 7th, so it will identify what voltage correlates.
Yes but lets be specific.
It will set the 'selector linkage' in the 7th gear position.
Seventh gear might well be engaged.
It depends on the map to operating system match as to whether the gear is still intact when under load.
Not really gear synchronization. It's sensor calibration.
On one hand, the fact that this calibration procedure can be done on the fly is pretty impressive. But on the other hand, the fact that such a sensor would lose its calibration during a race would seem to indicate a basic design flaw. It seems to be a case that they have addressed the symptom rather than the problem.
"Q: How do you make a small fortune in racing?
A: Start with a large one!"
On one hand, the fact that this calibration procedure can be done on the fly is pretty impressive. But on the other hand, the fact that such a sensor would lose its calibration during a race would seem to indicate a basic design flaw. It seems to be a case that they have addressed the symptom rather than the problem.
I agree, it tells you where the gear selection mechanism is, not what the geartrain is doing.
Less than heat, I think it is more due to the extremely high precision of machining we see those days. But this is very interesting ! I didn't know they were managing such small changes in the working order of the cars !
On one hand, the fact that this calibration procedure can be done on the fly is pretty impressive. But on the other hand, the fact that such a sensor would lose its calibration during a race would seem to indicate a basic design flaw. It seems to be a case that they have addressed the symptom rather than the problem.
Indeed. If it's the simple case of a potentiometer the only thing that matters is a ratio of resistances, and both would have the same thermal coefficient.. so that shouldn't be the problem.
Unless is some type of hall effect sensor, or any other sensor that just senses relative motion. If you are using relative motion you need to know all the time and never lose the count.
I'm no electronics expert, but if the sensor was a rotary pot that works on resistance wouldn't its voltage output vs the reference voltage be affected by large temperature swings?
Since the shift drum rotation angle increments from one gear to the next are likely quite small, one obvious remedy would be to use a rotary pot with a gear stage to give it better resolution.
"Q: How do you make a small fortune in racing?
A: Start with a large one!"
riff_raff wrote:I'm no electronics expert, but if the sensor was a rotary pot that works on resistance wouldn't its voltage output vs the reference voltage be affected by large temperature swings?
Since the shift drum rotation angle increments from one gear to the next are likely quite small, one obvious remedy would be to use a rotary pot with a gear stage to give it better resolution.
Good idea riff_raff.
Be even more complex and remote from the geartrain though.
You could always connect the drum to a gear lever, that would be positive.
Oh sorry that would mean having a driver to operate it.
With the ancient layshaft geartrains still in use, I cant realy see a reliable way of doing it.
