Interesting Article about F1 gearbox

Anthony_Ferrari · May 18, 2005

I stumbled accross this http://www.paddocktalk.com/news/html/modules.php?op=modload&name=News&file=article&sid=8639&newlang=&topic=7&catid=1

The Monaco Grand Prix is not just famous because of its history and its picturesque setting, but also because of the unique technical challenge it presents the drivers and engineers.

Quite frankly, if the race organisers applied to run a race through these twisty streets today for the first time, there is no way the governing body would sanction the event: a narrow bumpy track, peppered with road markings, drains and manhole covers does not fit with the sanitised world of F1 in the 21st century, while the facilities for VIP guests and, until the arrival of a new paddock last year, the teams, cannot match the modern facilities we encounter today.

But Formula 1 without Monaco is almost as unthinkable as Formula 1 without Ferrari!

Until a few years ago, part of a drivers armoury for Monaco, was heavy padding to his gearchanging hand, to prevent the gearlever causing blisters. Today, he simply flips the paddles on the back of the steering wheel. But while the driver might have an easier time, the gearbox itself still takes a tremendous amount of punishment at this track.

The gearbox is the component with one of the longest lead times on the car, in terms of its design, construction and development. It is not a true performance item, but rather a reliability item, with performance as a secondary function.

The design of the box is linked pretty closely with the cars aerodynamics, says Scuderia Ferrari Marlboro gearbox specialist, Diego Ioverno. The biggest challenge we face is to be able to come up with an effective gearbox in the layout space we are allowed.

The new rules concerning aerodynamics for 2005 have led to some major structural changes. This comes particularly from the new floor design which places it much closer to the gearbox.

In dealing with the changed regulations, our aim was to have at least the same performance from the overall car package and one of the areas that had to make some sacrifices was the gearbox, continues Ioverno. It is part of the job, we have to live with it and do our best, but it is fair to say that we work in a compromised environment because the gearbox can be viewed as a power wasting component located between the engine and the wheels!

In simple terms the bigger the gearbox, the more reliable it will be, but size and weight are the key to performance and engineers are always trying to lose weight in parts of the car to have the ballast as low as possible to lower the centre of gravity.

It is no secret that the F2005 gearbox has suffered some reliability problems early in its life and Ioverno reveals that these stemmed from a new concept in terms of the gearbox casing.

The main change for this year concerns the materials we use to manufacture the casing. Two years ago, we had a titanium casing. Then last year we had a titanium-carbon casing and this year we have increased the carbon content and carbon is a tricky material to work with. As soon as you use a new technology you have many lessons to learn and problems to solve. This is the challenge we face, combined with the fact that development time is very short.

It might seem strange that the casing, which the casual observer might think is just a container for the gears themselves, can cause a problem.

But the gears and other parts move in terms of the way the box lets them because the casing supports the internal components, explains Ioverno. The difficulty of managing this situation in engineering terms is that the metal internals and the carbon casing operate in different thermal conditions. So we have higher stress inside the gearbox.

In terms of gear shifts alone, Monaco provides the severest test of the year. Just for the race, the driver will make 3600 gear changes which is about 20% more than the lowest gear change circuit which is Monza, says Ioverno.

But the nature of the circuit adds further complications.

Monaco is a very strange, with all the kerbs the manhole covers, the drains. The driver never shifts in the same place in the same way, so setting up the gearbox for Monaco is a real challenge. As the car moves over a drain or a kerb, the entire transmission starts oscillating and if you try and shift gear at that point, it is very difficult to operate the shift. F1 gearboxes do not have syncromesh like a road car, so we synchronise the shift by controlling engine revs and coordinating it with the actuator that controls gear shift movement. So you have to be in phase with what you want to do. If everything is oscillating you are out of shape and risk big shocks or a bad shift or both.

So it is a misconception that the arrival of sophisticated gearchange technology has meant that drivers can no longer miss a gear shift. You have to consider that a shift lasts a few milliseconds, says Ioverno. In such a small range of time, a lot of things happen. So if you are doing a shift just as the engine takes a spike because of a kerb, the gearshift goes out of shape. You may also be unable to shift. Everything is on the limit and our actuators are not built to shift gears on a truck! If the torque you have to deal with is higher than a certain level then you can no longer achieve the gear shift.

At the moment you shift gear, the traction control has to be off. The two strategies cannot live together. Lets say the driver asks for a shift, so the system stops everything else, except safety issues and starts the process that leads to a gear change. The process is very fast and varies, depending on what gear shift you are making: the length of the gear shift itself changes a lot from gear to gear. It is less than 10 milliseconds, while the entire process averages 25-30 milliseconds.

The upshift only upsets the car in terms of power loss, but the downshift is very important in terms of the stability of the car. Because in a road car, if you go from fifth to first in one second, imagine what would happen to the rear wheels. In an F1 car a driver can ask to go from seventh to first in less than three seconds. Add these complex requirements to the challenge of the Monaco track surface and it is clear that the unglamorous gearbox plays a vital role in the glamorous Principality.
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I'd still like to see them using a clutch pedal and changing gear manually.

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