Examkin

Soru

Zorluk: OrtaSpeed on Curves and Downgrades

A commercial driver is approaching a sharp curve on an unfamiliar highway. Which statement best explains why the driver must slow down to a safe speed before entering the curve rather than braking while turning?

  1. A
    Braking after entering the turn reduces total stopping distance by eliminating perception and reaction time.
  2. Braking inside the curve demands combined turning and stopping traction, making wheels lock up easily and triggering a dangerous skid.Cevap
  3. C
    Braking mid-curve transfers vehicle weight to the outer tires, effectively countering centrifugal forces and improving roll stability.
  4. D
    Engaging the engine retarder while turning replaces the need for pre-curve slowing, especially on wet or slippery road surfaces.

Cevap

Braking inside the curve demands combined turning and stopping traction, making wheels lock up easily and triggering a dangerous skid.
Tires maintain a finite traction budget on any road surface. When navigating a curve, tire grip is heavily consumed by the lateral force required to steer the heavy vehicle. Applying service brakes inside the curve demands additional longitudinal grip, readily exceeding the friction threshold. This causes the wheels to lock up, resulting in skids, jackknifing, or rollover. Therefore, drivers must always slow to a safe speed before entering the curve.

Adım Adım Çözüm

1
Analyze tire traction physics during turning maneuvers.
Tires provide a finite amount of friction that must be shared between steering forces and braking forces.
When a vehicle rounds a curve, lateral friction is required to generate centripetal acceleration and keep the vehicle on its path.
2
Evaluate the effect of applying service brakes mid-turn.
Applying brakes introduces longitudinal force demands on already stressed tires, exceeding the total available traction limit.
Exceeding available friction causes wheel lockup, resulting in loss of steering control, drive-wheel skids, or trailer swing.
3
Determine the proper procedural countermeasure.
Speed must be adjusted downward before the front wheels turn into the curve.
Adjusting speed prior to curve entry allows all tire traction inside the curve to be dedicated to lateral stability and steering control.

Anahtar Kavram

Speed management and tire traction limits during curve negotiation
Tahmini Süre:1m 0s
Bu soruyu puanla

Konular

Speed on Curves and Downgrades

Bu konudan daha fazla soru