DOT Brake System Inspection & Adjustment Procedures

Question 1

When measuring brake adjustment on a Type 30 air brake chamber at a 90-degree angle, what is the maximum allowable pushrod stroke before the brake is considered out of adjustment?

Accepted Answer

2½ inches

Answer

For a Type 30 standard brake chamber measured at a 90-degree angle, the maximum allowable pushrod stroke is 2½ inches per the CVSA OOS criteria table. A stroke exceeding this limit means the brake is out of adjustment and the vehicle must be placed out of service if the number of out-of-adjustment brakes meets the OOS threshold.

Question 2

To correctly measure brake pushrod stroke during a roadside inspection, the inspector must apply the service brakes at what minimum air pressure before taking the measurement?

Accepted Answer

100 psi

Answer

CVSA procedures require that brake pushrod stroke be measured with the service brakes fully applied at or above 100 psi (or maximum system pressure). Taking the measurement at lower pressure will produce an artificially short stroke that does not reflect true brake adjustment.

Question 3

Under CVSA out-of-service criteria, a vehicle with four or more axles is placed out of service for brake adjustment defects when the number of brakes out of adjustment reaches what threshold?

Accepted Answer

25% of the vehicle's service brakes

Answer

The CVSA OOS criteria place a vehicle out of service when 25% or more of its service brakes are out of adjustment. For example, on a vehicle with 10 brakes, 3 or more out-of-adjustment brakes trigger an OOS order. This threshold applies regardless of axle position.

Question 4

An inspector examines a hydraulic brake system and finds the brake fluid level is below the manufacturer's minimum mark in the reservoir. Under CVSA criteria, this vehicle should be:

Accepted Answer

Placed out of service — a brake fluid level below the minimum is an OOS condition

Answer

CVSA OOS criteria list a brake fluid leak or a brake fluid level below the manufacturer's minimum as an immediate OOS condition for hydraulic brake systems. Low fluid indicates either a leak or chronic maintenance neglect, both of which can result in brake failure.

Question 5

Which brake component, when found cracked or broken during a CVSA Level I inspection, is an automatic out-of-service violation regardless of the number of axles affected?

Accepted Answer

A brake drum with a crack that opens to the friction surface

Answer

A brake drum that has a crack extending to the friction (braking) surface is an automatic OOS condition under CVSA criteria. Such a crack can propagate under braking stress, causing the drum to fracture and resulting in catastrophic brake failure. Surface cracks on the outer drum face that do not reach the friction surface may be evaluated differently.

DOT Inspector Certification Practice Test

DOT Inspector Certification Practice Test

DOT Brake System Inspection & Adjustment Procedures