DOT Vehicle Maintenance & Repair Standards 3

Question 1

When inspecting an automatic slack adjuster, at what pushrod stroke is the brake considered out of adjustment for a type-30 chamber?

Accepted Answer

Over 2 inches

Answer

For a Type 30 brake chamber, the out-of-service threshold is a pushrod stroke exceeding 2 inches at 90 psi according to CVSA criteria.

Question 2

A vehicle's air compressor governor cuts in at 100 psi and cuts out at 125 psi. Is this within acceptable range?

Accepted Answer

Yes, both values are within normal operating range

Answer

Normal cut-in pressure is 85–100 psi and cut-out is 120–135 psi, so 100/125 psi is within the acceptable operating range.

Question 3

Which of the following exhaust system defects is an automatic out-of-service condition?

Accepted Answer

Exhaust leak forward of or directly below the cab

Answer

An exhaust leak located forward of or directly below the cab is an out-of-service condition because carbon monoxide can enter the occupant compartment.

Question 4

A CMV's fuel tank has a pinhole leak that drips fuel when the vehicle is stationary. This defect is classified as:

Accepted Answer

An out-of-service condition

Answer

Any fuel system leak is an out-of-service condition under 49 CFR 393.67 because of the fire and explosion hazard it creates.

Question 5

What does the 'Low Air Warning' device on an air brake system activate?

Accepted Answer

When reservoir pressure drops below 60 psi

Answer

The low air warning device must activate before reservoir pressure drops below 60 psi, giving the driver time to safely stop the vehicle.

DOT Inspector Certification Practice Test

DOT Inspector Certification Practice Test

DOT Vehicle Maintenance & Repair Standards 3