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Zorluk: OrtaSpeed and Road Conditions

When driving a commercial motor vehicle on a roadway covered with packed snow where the normal posted speed limit is 50 mph50\text{ mph}, which combination of speed reduction and auxiliary brake management is required?

  1. A
    Reduce speed by one-third to approximately 33 mph33\text{ mph} and keep the engine retarder active to assist vehicle braking.
  2. Reduce speed to 25 mph25\text{ mph} or below and turn off the engine retarder completely.Cevap
  3. C
    Reduce speed to 25 mph25\text{ mph} or below and set the engine retarder to maximum resistance to reduce wear on service brakes.
  4. D
    Maintain 50 mph50\text{ mph} on straight road sections and apply heavy service braking while steering through curves.

Cevap

Reduce speed to 25 mph25\text{ mph} or below and turn off the engine retarder completely.
According to commercial driving regulations, drivers must reduce their speed by one-half or more on packed snow (slowing from 50 mph50\text{ mph} to 25 mph25\text{ mph} or less). Additionally, engine retarders must always be switched off whenever road surfaces are slippery (wet, snowy, or icy) because retarder braking torque can cause the drive wheels to lose traction and trigger a dangerous drive-wheel skid or jackknife.

Adım Adım Çözüm

1
Calculate the required speed reduction for packed snow.
Reduce speed by at least 1/21/2, lowering the maximum speed from 50 mph50\text{ mph} to 25 mph25\text{ mph} or less.
Official commercial driving standards require reducing speed by at least one-half on packed snow to maintain adequate stopping distance and tire traction.
2
Determine the proper setting for auxiliary brakes and engine retarders.
Disengage and turn off the engine retarder.
When drive wheels have reduced traction due to snow, ice, or water, retarder braking force can easily lock the drive wheels and cause an immediate skid or jackknife.

Anahtar Kavram

Speed adjustment on packed snow and engine retarder safety on slippery surfaces
Tahmini Süre:1m 0s
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Konular

Speed and Road Conditions

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