age 1 of 69
CDL Class A/B TEST STUDY GUIDE 2025/2026
ACCURATE QUESTIONS AND VERIFIED CORRECT
SOLUTIONS WITH RATIONALES || 100%
GUARANTEED PASS <RECENT VERSION>
Why must air tanks be drained? ......ANSWER........Compressed
air usually has some water and some
compressor oil in it, which is bad for the air brake
system. For example, the water can freeze in cold
weather and cause brake failure. The water and oil
tend to collect in the bottom of the air tank. Be sure that you
drain the air tanks completely
,age 2 of 69
What is a supply pressure gauge used for?
......ANSWER........These gauges tell you how much pressure is in
the
air tanks.
All vehicles with air brakes must have a low air pressure warning
signal. True or False? ......ANSWER........True (A low air pressure
warning signal is required on
vehicles with air brakes. A warning signal you can see must come
on before the air pressure in the tanks falls below 60 psi.)
What are spring brakes? ......ANSWER........emergency brakes
and parking brakes. They must be held on by mechanical force
,age 3 of 69
Front wheel brakes are good under all conditions. True or False?
......ANSWER........True (Limiting valves were used to reduce the
chance of the front wheels skidding on slippery surfaces.
However, they actually reduce the stopping power of the
vehicle)
How do you know if your vehicle is equipped with antilock
brakes? ......ANSWER........Check the certification label for the
date of manufacture to
determine if your vehicle is equipped with
What is a dual air brake system? ......ANSWER........has two
separate air brake systems, which use a single
set of brake controls. Each system has its own air tanks, hoses,
lines, etc. One system typically operates the regular brakes on
, age 4 of 69
the rear axle or axles. The other system operates the regular
brakes on the front axle
What are the slack adjusters? ......ANSWER........is a lever arm
connected to the brake chamber's push rod at the clevis
assembly. it adjusts the brakes to make up for lining wear.
How can you check slack adjusters? ......ANSWER........Park on
level ground and chock the wheels to prevent the vehicle from
moving. Release the parking brakes
so you can move the slack adjusters. Use gloves and pull hard on
each slack adjuster that you can reach. If a slack adjuster moves
more than about one inch where the push rod attaches to it, it
probably needs adjustment. Adjust it or have it adjusted.
Vehicles with too much brake slack can be very hard to stop.
CDL Class A/B TEST STUDY GUIDE 2025/2026
ACCURATE QUESTIONS AND VERIFIED CORRECT
SOLUTIONS WITH RATIONALES || 100%
GUARANTEED PASS <RECENT VERSION>
Why must air tanks be drained? ......ANSWER........Compressed
air usually has some water and some
compressor oil in it, which is bad for the air brake
system. For example, the water can freeze in cold
weather and cause brake failure. The water and oil
tend to collect in the bottom of the air tank. Be sure that you
drain the air tanks completely
,age 2 of 69
What is a supply pressure gauge used for?
......ANSWER........These gauges tell you how much pressure is in
the
air tanks.
All vehicles with air brakes must have a low air pressure warning
signal. True or False? ......ANSWER........True (A low air pressure
warning signal is required on
vehicles with air brakes. A warning signal you can see must come
on before the air pressure in the tanks falls below 60 psi.)
What are spring brakes? ......ANSWER........emergency brakes
and parking brakes. They must be held on by mechanical force
,age 3 of 69
Front wheel brakes are good under all conditions. True or False?
......ANSWER........True (Limiting valves were used to reduce the
chance of the front wheels skidding on slippery surfaces.
However, they actually reduce the stopping power of the
vehicle)
How do you know if your vehicle is equipped with antilock
brakes? ......ANSWER........Check the certification label for the
date of manufacture to
determine if your vehicle is equipped with
What is a dual air brake system? ......ANSWER........has two
separate air brake systems, which use a single
set of brake controls. Each system has its own air tanks, hoses,
lines, etc. One system typically operates the regular brakes on
, age 4 of 69
the rear axle or axles. The other system operates the regular
brakes on the front axle
What are the slack adjusters? ......ANSWER........is a lever arm
connected to the brake chamber's push rod at the clevis
assembly. it adjusts the brakes to make up for lining wear.
How can you check slack adjusters? ......ANSWER........Park on
level ground and chock the wheels to prevent the vehicle from
moving. Release the parking brakes
so you can move the slack adjusters. Use gloves and pull hard on
each slack adjuster that you can reach. If a slack adjuster moves
more than about one inch where the push rod attaches to it, it
probably needs adjustment. Adjust it or have it adjusted.
Vehicles with too much brake slack can be very hard to stop.
