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Zorluk: Çok zorBrake System Components Inspection

An operator is evaluating the foundation braking system on a tractor-trailer combination using the applied stroke method. The operator properly chocks the wheels, pushes in both dashboard valves to completely release the spring brakes, and has an assistant hold a steady 95 psi service brake application. The operator records the following pushrod travel measurements:

- On the tractor's drive axle: A Type 30 brake chamber with standard round pneumatic ports measures 2.25 inches of stroke.
- On the trailer axle: A Type 30 brake chamber with square pneumatic ports and an attached trapezoidal tag measures 2.25 inches of stroke.

Based on standard Commercial Vehicle Safety Alliance (CVSA) criteria, which of the following best describes the compliance status of these specific brake assemblies?

  1. The drive axle brake is out of adjustment, but the trailer axle brake is within acceptable operating limits.Cevap
  2. B
    Both the drive axle and trailer axle brakes exceed the maximum allowable stroke and are out of adjustment.
  3. C
    Both the drive axle and trailer axle brakes are within acceptable operating limits because neither exceeds 2.5 inches of travel.
  4. D
    Neither measurement is valid for compliance determination, because an applied stroke test requires the spring brakes to remain engaged.

Cevap

The drive axle brake is out of adjustment, but the trailer axle brake is within acceptable operating limits.
The inspection procedure was performed completely correctly. A standard Type 30 chamber, visually identified by round air ports, has a maximum legal applied stroke of 2.0 inches, meaning the 2.25-inch drive axle measurement constitutes an out-of-adjustment defect. Conversely, a Type 30 Long-Stroke (LS) chamber, identified by square air ports and a trapezoidal tag, has an extended maximum limit of 2.5 inches, meaning the 2.25-inch trailer axle measurement is perfectly compliant.

Adım Adım Çözüm

1
Verify the inspection procedure setup.
The setup (wheels chocked, spring brakes released, 90-100 psi service application) is strictly correct for safely measuring applied pushrod stroke.
Measurements taken with spring brakes engaged are inaccurate due to compounding forces.
2
Evaluate the drive axle brake chamber measurement.
The chamber is a standard Type 30 (indicated by round ports). Its readjustment limit is 2.0 inches. Since it measures 2.25 inches, it is out of adjustment.
Standard chambers have stricter stroke limits than their long-stroke counterparts.
3
Evaluate the trailer axle brake chamber measurement.
The chamber is a Long-Stroke Type 30 (indicated by square ports and a trapezoidal tag). Its readjustment limit is 2.5 inches. Since it measures 2.25 inches, it is within legal limits.
Long-Stroke chambers are specifically designed to provide a wider safety margin and longer acceptable travel.

Anahtar Kavram

Brake Chamber Identification and Pushrod Stroke Limits
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Konular

Brake System Components Inspection

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