Felipe Massa’s quote at the weekend about the new ‘brake-by-wire’ systems on the 2014 F1 cars taking some getting used to has sparked a lot of discussion on the JA on F1 site, with readers wanting to know more about what it is and how it works.
Let’s start with an explanation from the Sauber F1 team, “The braking system concept is totally new, taking the form of a brake-by-wire system for the first time at the rear wheels. This has become necessary due to the significantly increased performance of the ERS, which requires much greater variations in rear wheel braking torque than previously. With brake-by-wire, an electronic system measures how hard the driver presses the brake pedal and then – using the additional information from energy recuperation – determines in a split-second the amount of braking pressure that should be fed through to the rear brake callipers.”
In other words, because the ERS (Energy Recovery System) is so much more powerful on these new cars compared to the KERS on the 2013 cars, harvesting energy when the car is braking – 161bhp of energy compared to 80bhp with the KERS – it is essential that the engineers install a system to compensate for the powerful effect that has on brake balance and braking stability. This makes it acceptable for the driver and doesn’t destabilise the car with a sudden balance shift. A lot of the lap time in modern F1 comes from stable braking.
Massa’s quote was: “The brakes work in a different way. It’s electronic brakes, brake-by-wire, and I still need to improve the way I’m braking because it’s different. It’s a little bit strange sometimes,” he said.
So, how does it work?
An F1 car has two brake systems for safety – front and rear – so that if one fails the other will stop the car. For 2014, the rear brake system has the brake-by-wire, which assesses how much brake pressure the driver has called for when he presses the pedal and an electronic system modulates the power to the rear brakes, allowing for the ERS effect, that is taking energy to charge up the kinetic motor generator unit (known as MGU-K). It smooths out the process, slowing the car in a consistent way at the same time as ensuring the maximum energy harvest for the ERS.
Ideally, the driver would feel nothing unusual with this system, in that it should provide consistent, stable braking on demand. The job of the new rear brakes system is to ensure consistency. Some people might argue that the electronic assistance to the driver makes it a “driver aid” and in the sense that without it, it would be difficult to maintain a brake system that the drivers would be happy with. This damps it out. But as it’s written into the regulations it doesn’t fall foul of the regulation saying that the driver must drive “alone and unaided” – a rule that prevents the use of traction control, ABS and countless other technical goodies.
Here is the exact wording of the new technical regulation on brake by wire.