Adjustment & Testing Flashcards

A vehicle's foundation brakes are considered out of adjustment when the pushrod stroke exceeds which FMCSA standard?

Answer: The maximum stroke listed in the Federal Motor Carrier Safety Regulations for that chamber type

FMCSA regulations set maximum allowable pushrod stroke by chamber type; exceeding the listed limit for that specific chamber type means the brakes are out of adjustment.

How often should manual slack adjusters be checked and adjusted?

Answer: Daily, as part of the pre-trip inspection

Manual slack adjusters require daily inspection during pre-trip checks to ensure brake adjustment is within limits, since they do not self-adjust like automatic units.

What tool is typically used to measure brake chamber pushrod stroke?

Answer: A ruler or tape measure

A ruler or tape measure is used to mark the pushrod position before and after brake application to determine how far the rod travels (applied stroke).

When performing a brake adjustment, what is the risk of over-tightening the slack adjuster?

Answer: The brake shoes will drag against the drum, causing heat and premature wear

Over-tightening reduces clearance so much that brake shoes contact the drum even when the brakes are released, causing constant friction, heat buildup, and accelerated wear.

Which statement about automatic slack adjusters is TRUE?

Answer: They still require periodic inspection to verify they are functioning correctly

Even though automatic slack adjusters adjust on their own during braking, drivers must still inspect them during pre-trip checks to verify they are working properly and not damaged.

What is the brake 'free stroke' and why is it important?

Answer: The initial pushrod movement before the brake shoes contact the drum; it should be short to maximize effective braking stroke

Free stroke is the initial pushrod travel before the brake lining contacts the drum. A short free stroke leaves more usable stroke for actual braking force, improving stopping performance.