Examkin

Soru

Zorluk: OrtaStopping Distance Components

A fleet safety director is training drivers transitioning from hydraulic-braked delivery vehicles to air-braked straight trucks. When traveling on a dry, level highway at 55 mph55\text{ mph}, which additional factor must the driver account for in total stopping distance that is unique to air brake systems, and approximately how much distance does it add?

  1. A
    Perception distance, which adds approximately 142 feet142\text{ feet} (1.75 seconds1.75\text{ seconds}) for the driver's eyes and brain to recognize a roadway hazard.
  2. B
    Reaction distance, which adds approximately 61 feet61\text{ feet} (0.75 seconds0.75\text{ seconds}) for the driver to move their foot from the accelerator to the brake pedal.
  3. Brake lag distance, which adds approximately 32 feet32\text{ feet} (0.5 seconds0.5\text{ seconds}) while air flows through the lines to fully engage the brake shoes.Cevap
  4. D
    Following distance buffer, which adds approximately 100 feet100\text{ feet} (1 second1\text{ second} per 10 feet10\text{ feet} of vehicle length) for space cushion safety.

Cevap

Brake lag distance, which adds approximately 32 feet32\text{ feet} (0.5 seconds0.5\text{ seconds}) while air flows through the lines to fully engage the brake shoes.
Air brake systems require compressed air to flow through the pneumatic plumbing to build pressure in the brake chambers. This mechanical delay takes approximately 0.5 seconds0.5\text{ seconds} (brake lag), adding roughly 32 feet32\text{ feet} of travel at 55 mph55\text{ mph} before deceleration physically begins.

Adım Adım Çözüm

1
Identify the standard stopping distance components for hydraulic versus air brake systems.
Hydraulic brake vehicles have 3 components (Perception + Reaction + Braking Distance). Air brake vehicles have 4 components (Perception + Reaction + Brake Lag + Braking Distance).
Air brake systems rely on compressed air traveling through valves and lines, introducing a mechanical delay before friction surfaces make contact.
2
Calculate the distance added by air brake lag at a highway speed of 55 mph55\text{ mph}.
At 55 mph55\text{ mph} (80.7 ft/s80.7\text{ ft/s}), a 0.5 second0.5\text{ second} brake lag adds approximately 80.7×0.5≈32 feet80.7 \times 0.5 \approx 32\text{ feet} (or ≈40 feet\approx 40\text{ feet} under conservative manual estimates).
The vehicle continues rolling at full cruising speed during the half-second delay before the air pressure activates the brake shoes.

Anahtar Kavram

Air Brake Lag Component in Total Stopping Distance
Tahmini Süre:1m 0s
Bu soruyu puanla

Konular

Stopping Distance Components

Bu konudan daha fazla soru