The 2014 F1 cars adopt sophisticated braking systems that combine the forces of the Energy Recovery System and a traditional hydraulic system. But this hasn’t been without its problems, as we’ve seen in some of the toughest races this year.
The revolution in Formula 1 in 2014 is not just about the engines, or the power units (the complex hybrid systems) as they’re referred to this year. One of the most innovative aspects has actually been the integration of the braking system with the power unit. The innovation, however, seems to have created some difficulty for several drivers – such as Raikkonen and Vettel, at least in the early part of the season.
There are several tracks that are particularly hard on the brakes, due to fast straights and hard braking zones – like Monza and Canada for instance. Not coincidentally, then, Canada recorded one of the rare double failures for the dominating Mercedes machines. The reason was a malfunction of the electronic high voltage control system, which resulted in the loss of MGU-K (the Energy Recovery System). And so the drivers were deprived of another essential element of F1 2014 – brake-by-wire, or the electronic braking system.
A very complex deviceBrembo engineers helped us understand this complex solution. The Italian company, after all, is massively active in the world of Grand Prix racing – and is the sole supplier (of all, or part of the braking systems) to seven teams, including top teams such as Mercedes, Red Bull, and Ferrari. The introduction of the electronic brake at the rear, achieved thanks to the counter-torque provided by the KERS system (which, remember, charges the batteries during braking, and then delivers acceleration of up to 120kW and 2MJ of energy per lap), has not eliminated the presence of the traditional system – based on discs and calipers (but no ABS, as the rules require).
The FIA, however, has set specific limits for these elements as well – the discs (carbon based) can have a maximum diameter of 278mm and a maximum thickness of 28mm, while the weight must be 1.5kgs. However, at the rear, they now adopt smaller (in the region of 270mm) and thinner discs, given the slowing effect exerted by the KERS system. If that fails, as happened on the Mercedes in Canada, it can undermine the system. The caliper weight can oscillate between 1.6 to 1.8kgs and have between four to six pistons. Finally, the pads have a surface area of about 77cm2, and their thickness is between 18 and 25mm.
The whole system this year is subjected to greater stress, due to the weight of the cars and the significant decrease (commissioned by the regulations) in downforce – so braking distances are longer than before, even if the driver continues to apply considerable pressure on the pedal (120-140kgs, achieved thanks to the thrust of the body while decelerating). Initially, when braking – for about 0.5 to 2 seconds – pressure is exerted through the left pedal on two hydraulic pumps, one connected to the front calipers, the other to the rear calipers.
The braking toque, developed by the electric motor, only comes into play during the second phrase of the slowing process through a kind of black box (explained in the box below). Of particular interest is the presence of an emulator that replicates the response of the rear calipers – a sort of artifice designed to allow the driver to feel the pedal with the same sensation produced by a traditional braking system, even when the operation is handled autonomously by the electronic control unit. The third pump is electro-hydraulically operated, and acts on rear discs on the basis of predetermined maps – developed by each team taking into account the speed, aerodynamic load, the temperature of the discs, and the need to deliver constant braking torque to avoiding failure at the rear. The disc temperatures are around 300-350°C at the start of braking and can then go all the way up to 1,000°C – these values are read by infrared sensors and are transmitted in real time via telemetry to the pits, where the race engineers can alert the driver of the need to reduce or raise them.
As you can see, we’re very far from theses braking systems being used on everyday machines – even if the technology were to percolate down from hybrid high performance cars to more regular serial production machines. For now, Brembo is committed to providing each team a set of forty discs per season – plus an average of 10 sets of front calipers and 12 rear. After approximately 3,200 kilometres of use, the calipers have to go back to the Bergamo based company – where they are disassembled, checked with the aid of special equipment, and overhauled, with the replacement of components such as titanium pistons, seals and purge valves. Operations are carried out by hand – because, even in this age of high technology, Formula 1 machines are still made with the finest craftsmanship.
Taking a beating on the kerbs
Brembo is the only manufacturer to have two-stage brake pumps – if the smaller diameter (16mm) makes the pedal a little bit more modular, the larger brake pump (22mm) enables a higher flow of fluid. Consequently, the pistons in the calipers are quickly recovered after the beating they take every time the car tackles the kerbs on the track
The consequences of heat
Despite the fact that the calipers (left) rely on the unique characteristics of a forged aluminium-lithium alloy (below), the extremely high temperatures can gradually reduce the mechanical strength of the part and it’s appropriate to replace them after six complete overhauls at the Brembo laboratory
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