Examkin

Soru

Zorluk: OrtaSpeed on Curves and Downgrades

An interstate exit ramp displays a yellow warning sign indicating a sharp curve with a 30 mph advisory speed. What speed and control procedure should a tractor-trailer operator follow when taking this ramp?

  1. A
    Enter the ramp at highway cruising speed and apply firm service braking while turning through the curve to meet the 30 mph target.
  2. Slow down to a speed 5 to 10 mph below the posted advisory speed before entering the curve, then maintain light throttle through the turn.Cevap
  3. C
    Maintain exactly 30 mph throughout the curve, because posted advisory speeds are calculated specifically for commercial vehicles.
  4. D
    Shift the transmission into neutral upon entering the curve and use constant light brake pressure to regulate speed.

Cevap

Slow down to a speed 5 to 10 mph below the posted advisory speed before entering the curve, then maintain light throttle through the turn.
Posted advisory speeds on curves are engineered for passenger cars with low centers of gravity. Heavy commercial vehicles must reduce speed to 5 to 10 mph below the advisory speed before entering the curve, completing all braking on the straightaway and applying slight engine throttle through the turn to keep the combination stable.

Adım Adım Çözüm

1
Evaluate the posted advisory speed in relation to commercial vehicle physical dynamics.
Recognize that advisory speeds are set for passenger cars, so a heavy combination vehicle requires a speed roughly 5 to 10 mph lower.
Commercial motor vehicles have a much higher center of gravity and are prone to rolling over at passenger-car speeds.
2
Complete all deceleration and downshifting on the straight approach before reaching the curve.
The vehicle enters the turn at the safe target speed without needing active service brake application during the turn.
Braking while turning consumes tire traction required for directional control and risks wheel lockup or skidding.
3
Maintain slight, steady engine power throughout the curve.
The vehicle combination remains stable and tracks smoothly through the apex to the exit.
Light engine power maintains forward drive traction and stabilizes the tractor-trailer combination.

Anahtar Kavram

Adjusting speed below posted advisory limits prior to curve entry
Tahmini Süre:1m 0s
Bu soruyu puanla

Konular

Speed on Curves and Downgrades

Bu konudan daha fazla soru