Brake plates

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Brake plates with visible damage to the carcass on a kart tire

A brake plate is a flat spot on the tread of a tire that can be caused by a locking wheel during extreme braking on a solid surface such as asphalt . A tire is rubbed off at only one point during the braking process, causing a tire imbalance .

In rail vehicles, this phenomenon is known as a flat spot .

The anti-lock braking system counteracts this effect in road vehicles ; Brake plates therefore only occur on vehicles without ABS (many motorcycle models; racing) or when the brakes are blocked (e.g. truck trailers with a defective compressed air hose).

causes

Braking mistake of Heikki Kovalainen in a McLaren-Mercedes

In motorsport, a racing driver strives to decelerate his vehicle as late and as hard as possible. Since the use of an anti-lock braking system is forbidden in most racing series , a wheel can lock if the vehicle decelerates too far. The friction of the tire on the road surface leads to high temperatures and heavy abrasion at this point on the tire.

Even when turning , it is easy for several tires to brake flat if the car is braked during the turning process and the wheels are intentionally locked.

Tires in road traffic are designed for a much higher mileage than in racing (different degree of hardness), so that the friction and thus also the wear of a tire on the road surface is significantly lower. In addition, in most vehicles the ABS prevents the wheels from standing still in order to maintain maneuverability.

In the case of truck trailers, a defective or not connected compressed air hose of the compressed air brake leads to blocked wheels on the trailer - for safety, so that a stand-alone or demolished trailer stops. If the tractor pulls the trailer anyway, brake plates are created on the trailer wheels.

Consequences

The consequences of a brake plate are strong vibrations in the vehicle, which can lead to a deterioration in driving behavior and also to a higher level of noise. In most cases, due to the larger contact area at this point, a tire tends to block again even with a slightly lower braking effect, and thus further intensify the vibrations.

If the braking force is only low, the vibrations can disappear again after a short time due to the further wear and tear of the tire; a time-consuming tire change is only useful in a few cases. With "larger" brake plates, however, the tread may be worn down to the carcass , and a tire change is essential here.

A well-known example of the consequences of a brake plate occurred at the 2005 European Grand Prix at the Nürburgring, when tire changes were not allowed in Formula 1 . Kimi Raikkonen , who was in the lead, retired on the last lap after breaking the suspension while braking. This break was caused by vibrations caused by a brake plate. Raikkonen had braked several times during the race. In the following season, tire changes were allowed again.

With truck tires, tire damage can lead to the tire bursting while driving.

Individual evidence

  1. Bernd Heissing, Metin Ersoy, Stefan Gies (eds.): Chassis manual : Fundamentals, driving dynamics, components, systems, mechatronics, perspectives . 3rd, revised and expanded edition. Vieweg + Teubner Verlag, 2011, ISBN 978-3-8348-0821-9 , wheel brakes and brake systems, p. 194 ( Google books [accessed March 24, 2012]).
  2. Bert Breuer, Karlheinz H. Bill (ed.): Brake manual: Fundamentals, components, systems, driving dynamics . 3rd, completely revised and expanded edition. Vieweg Verlag, Wiesbaden 2006, ISBN 3-8348-0064-3 , brake energy transmission and modulation, p. 111 .
  3. Excitement after Raikkonen's last-minute crash. motorsport-total.com, May 30, 2005, accessed March 20, 2012 .