What is the air compressor’s job in an air brake system?
Correct answer: Pump air into the storage tanks
The compressor supplies compressed air to the reservoirs used by the brake system.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.1 Air Compressor, printed page 5-1 (physical PDF page 1) ↗
At approximately what tank pressure does the governor normally cut out the air compressor?
Correct answer: 125 psi
The governor normally stops compressor loading near 125 psi, although manufacturer specifications may vary.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.2 Air Compressor Governor; 5.3.3 Check Air Compressor Governor Cut-in and Cut-out Pressures (printed 5-10), printed page 5-1 (physical PDF page 1) ↗
At approximately what pressure does the governor normally allow the compressor to cut in again?
Correct answer: 100 psi
The governor normally restarts compressor loading near 100 psi. Check the manufacturer specifications for the particular vehicle; the final air-brake check uses those specified pressures.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.2 Air Compressor Governor; 5.3.3 Check Air Compressor Governor Cut-in and Cut-out Pressures (printed 5-10), printed page 5-1 (physical PDF page 1) ↗
Why must moisture and oil be removed from air storage tanks?
Correct answer: Water can freeze and interfere with braking
Water and oil collect in the tanks; frozen water can obstruct the system and cause brake failure.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.4 Air Tank Drains, printed page 5-2 (physical PDF page 2) ↗
When should manually drained air tanks normally be emptied?
Correct answer: At the end of each driving day
Manual tank drains should be opened completely at the end of each day of driving.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.4 Air Tank Drains, printed page 5-2 (physical PDF page 2) ↗
What does the air-system safety valve protect against?
Correct answer: Excessive pressure
The valve protects the first tank and the rest of the system from overpressure and usually opens near 150 psi.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.6 Safety Valve, printed page 5-2 (physical PDF page 2) ↗
Why should a driver avoid unnecessary repeated brake-pedal applications?
Correct answer: Air use may exceed compressor output
Each release exhausts compressed air, so repeated applications may lower pressure to an unsafe level.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.7 The Brake Pedal, printed page 5-2 (physical PDF page 2) ↗
What can increasing application pressure needed to hold the same speed indicate?
Correct answer: The brakes may be fading
A rising application-pressure requirement can signal brake fade, poor adjustment, leaks, or mechanical trouble.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.10 Application Pressure Gauge, printed page 5-4 (physical PDF page 4) ↗
In New York CDL manual section 5.3.3, the low-pressure warning must activate before tank pressure falls below what threshold?
Correct answer: 60 psi
For this final air-brake check, New York specifies that the warning must come on before pressure falls below 60 psi in the tank, or the lowest-pressure tank of a dual system. A vehicle may warn earlier. On the road, stop safely when a low-air warning occurs; do not wait for spring brakes.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.3.3 Step 7 Final Air Brake Check — Test Low Pressure Warning Signal, printed page 5-9 (physical PDF page 9) ↗
What holds spring brakes off while a vehicle is being driven normally?
Correct answer: Air pressure
Air pressure compresses the powerful springs; loss of pressure lets the springs apply the brakes.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.14 Spring Brakes, printed page 5-4 (physical PDF page 4) ↗
At what approximate pressure range do tractor and straight-truck spring brakes come fully on?
Correct answer: 20 to 45 psi
The manual gives a 20–45 psi range for tractor and straight-truck spring brakes to come fully on, typically 20–30 psi. The vehicle's specifications matter. Stop safely at the low-air warning rather than waiting for the spring brakes.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.14 Spring Brakes, printed page 5-4 (physical PDF page 4) ↗
On a newer air-brake vehicle, how is the parking brake normally applied?
Correct answer: Pull out the yellow diamond-shaped control
Pulling out the yellow push-pull knob releases air from the spring brakes so they apply.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.15 Parking Brake Controls, printed page 5-5 (physical PDF page 5) ↗
Why should the foot brake not be pressed while spring brakes are already applied?
Correct answer: Combined spring and air forces may damage the brakes
Some systems can be damaged when air pressure adds to the force of applied spring brakes.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.1.15 Parking Brake Controls — Caution, printed page 5-5 (physical PDF page 5) ↗
If an ABS-only malfunction occurs and there is no separate service-brake fault, what braking capability remains?
Correct answer: Normal braking remains, but ABS needs service
An ABS malfunction does not remove normal service braking. Continue to use the brakes normally and arrange ABS service promptly; do not assume ABS protection remains available.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.4.2 Braking with Antilock Brakes (continued), printed page 5-11 (physical PDF page 11) ↗
On a reachable S-cam slack adjuster, what manually pulled movement at the push-rod connection suggests a need for adjustment?
Correct answer: More than about one inch
With wheels chocked and parking brakes released, manually pulling a reachable S-cam slack adjuster more than about one inch at the push-rod connection signals trouble. This is not a universal applied push-rod stroke limit. Have faults repaired; routinely adjusting automatic adjusters is not a substitute for repair.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.3.2 During Step 5 Walkaround Inspection — Check Slack Adjusters on S-cam Brakes, printed page 5-8 (physical PDF page 8) ↗
In New York's applied leakage check, after applying at least 90 psi with the brake pedal and allowing the initial drop, what is the maximum one-minute loss for a single vehicle?
Correct answer: 3 psi
Secure the vehicle against rolling, fully charge the system, shut off the engine and release the parking brakes. Apply 90 psi or more with the brake pedal. After the initial pressure drop, a single vehicle must not lose more than 3 psi in one minute. This is not the brakes-released test.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.3.3 Step 7 Final Air Brake Check — Test Air Leakage Rate, printed page 5-9 (physical PDF page 9) ↗
In New York's applied leakage check for a two-vehicle air-brake combination, what is the maximum one-minute loss after a pedal application of at least 90 psi and the initial drop?
Correct answer: 4 psi
Secure the combination against rolling, fully charge the system, shut off the engine and release the parking brakes. Apply 90 psi or more with the brake pedal. After the initial drop, the combination must not lose more than 4 psi in one minute. This is separate from the static test.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.3.3 Step 7 Final Air Brake Check — Test Air Leakage Rate, printed page 5-9 (physical PDF page 9) ↗
In New York CDL manual section 5.3.3, what loss rate should a single vehicle stay below during the brakes-released leakage check?
Correct answer: 2 psi in one minute
Secure the vehicle against rolling, fully charge the system, stop the engine and release the brakes. The chapter specifies a loss rate of less than 2 psi per minute for a single vehicle. This is the brakes-released test, not the applied test.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.3.3 Step 7 Final Air Brake Check — Test Air Leakage Rate, printed page 5-9 (physical PDF page 9) ↗
At operating engine rpm, what pressure buildup does New York CDL manual section 5.3.3 specify for a typical dual air system?
Correct answer: 85 to 100 psi within 45 seconds
Check at operating rpm. The handbook allows longer buildup for vehicles with larger-than-minimum air tanks; consult the manufacturer specifications. Do not apply the older single-system idle-speed test to this dual system.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.3.3 Step 7 Final Air Brake Check — Check Rate of Air Pressure Buildup, printed page 5-9 (physical PDF page 9) ↗
How should service brakes be checked after normal air pressure is restored?
Correct answer: Move forward slowly at about 5 mph and apply them firmly
In a safe test area, check normal air pressure, release the parking brake, move forward at about 5 mph and apply the service brakes firmly. Check for pulling, an unusual feel or delayed stopping.
Source: New York State Commercial Driver's Manual CDL-10 (11/25), section 5.3.3 Step 7 Final Air Brake Check — Test Service Brakes, printed page 5-10 (physical PDF page 10) ↗
