On what kind of road surface are vehicle wheels most prone to locking during braking?
2 Answers
Vehicle wheels are prone to locking during braking on road surfaces with low friction coefficients, such as common icy or snowy roads. This occurs because such surfaces generate relatively low friction. When the friction between the brake pads and brake discs exceeds the friction between the road surface and the wheels, the wheels lock up and skid. Wheel lock refers to a phenomenon where the brake clamps the tire, preventing it from moving relative to the brake, causing it to slide against the ground. Wheel lock can be categorized into dynamic lock and static lock. Dynamic lock occurs when the front wheels lock and skid first during driving, causing the vehicle to lose steering capability; if the rear wheels lock and skid first, even a slight lateral force can cause the vehicle to skid sideways; if both front and rear wheels lock simultaneously, the vehicle will slide in a straight line. Static lock refers to a situation where the vehicle is parked, and one or more wheels remain locked, causing them to skid when the driver attempts to restart, preventing the vehicle from moving normally.
While driving, I noticed that the road surfaces where a vehicle's wheels are most prone to locking up during braking are absolutely those smooth as mirror ice or icy and snow-covered sections. This is because the friction coefficient on ice is almost zero, making it impossible for tires to grip the road, causing the wheels to instantly lock and skid during sudden braking. I've experienced several close calls while driving up steep hills in winter, feeling the car slide forward like it's on ice. Similarly, wet asphalt roads after rain or areas with standing water are also problematic, as the water layer separates the tires from the road surface, reducing friction—especially when passing through tunnels with accumulated water on highways, where it's necessary to slow down in advance. Additionally, surfaces with oil stains or loose gravel are prone to locking up, such as dusty areas near construction zones. The ABS system can help mitigate this, but don't rely on it entirely on these hazardous surfaces; it's still crucial to drive slowly and maintain a safe distance.
