Flat spot
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A flat spot, or wheel flat, also called spalling or shelling, is a fault in
Consequences
NORAC guidelines state that the train may continue at normal speed if the flat spot is less than 2.5 inches long, or, in the case of multiple adjacent flat spots, each is shorter than 2 inches.
If the flat spot is sufficiently large, strands of molten metal may have stuck on one side of the flat spot, making it impossible for the wheel to turn due to insufficient clearance between the rolling surface and the
In extreme cases such as the
Automobile use
Engine response
In
Car tires
![A Formula One car with smoke coming from the front right tire after a brake lockup](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Hamilton_Bahrain_2016_lockup.jpg/220px-Hamilton_Bahrain_2016_lockup.jpg)
A literal flat spot can occur on car tires if the vehicle is parked without moving for some time (generally longer than a week), and the tire deformation at the bottom of the wheel becomes semi-permanent. The flat spot gradually relieves itself when the car is driven but can temporarily give similar symptoms to an unbalanced wheel. Cars being laid up for extended periods, or intermittently-used caravans and trailers, should be kept on axle stands (tyres not in contact with the ground) or have the tires over-inflated to eliminate or reduce this problem. "Tire savers", curved wheel stands, are also available for use during storage. These reduce or avoid the problem by cradling the lower part of the tire tread and preventing the usual deformation where it rests on the ground.
Another cause seen frequently in racing is locking the wheels during heavy braking.[4]
References
- ^ "NORAC OPERATING RULES - PDF Free Download". docplayer.net. Retrieved 2023-12-07.
- ^ "Automotive Operation And Maintenance". ECHOcommunity. Retrieved 2023-08-28.
- ^ "What flat spots can mean and why they are a problem". autocra. 2016-10-14. Retrieved 2023-08-28.
- ^ "Glossary". F1. Formula One World Championship Limited. Retrieved 4 November 2018.
The term given to the area of a tyre that is worn heavily on one spot after a moment of extreme braking or in the course of a spin. This ruins its handling, often causing severe vibration, and may force a driver to pit for a replacement set of tyres.