1. Which color coding standard applies to trailer air line connections on a commercial motor vehicle?

2. After backing under a trailer and connecting the fifth wheel to the kingpin, which method confirms that the fifth wheel is properly locked?

3. A driver is preparing to descend a long mountain grade with a loaded tractor-semitrailer. What is the correct use of the trailer hand valve (trolley valve) during this descent?

4. A driver is coupling a tractor to a semitrailer at a loading dock. The driver has positioned the tractor, connected the air lines, supplied air to the trailer, tested the trailer brakes, and backed under the trailer until the fifth wheel engaged. What should the driver do NEXT to complete the coupling procedure safely?

5. A driver is approaching a cloverleaf exit ramp from an interstate highway while operating a loaded tractor-semitrailer with a high center of gravity cargo. The ramp has a posted advisory speed of 25 MPH. What is the safest approach to negotiating this curve to prevent rollover?

6. A driver is traveling on a wet, slippery highway when the tractor begins to skid and the trailer swings outward, creating a jackknife situation where the trailer is pushing the tractor sideways. What is the correct immediate response to recover from this jackknife?

7. A driver has just coupled a tractor to a semitrailer and supplied air to the trailer system. The trailer air tanks have built to full pressure, and the driver wants to test the trailer brakes before proceeding. What is the correct method for testing trailer brake function?

8. A driver couples a tractor to a semitrailer and performs the tug test. When pulling forward gently against the trailer brakes, the trailer moves forward several inches and the driver hears a clunk from the fifth wheel area. The driver stops, inspects the fifth wheel, and finds that the locking lever is not fully in the locked position. What is the most likely cause of this coupling failure, and what should the driver do?

9. A driver is descending a 5% mountain grade in rainy conditions with a loaded tractor-semitrailer. The driver applies the brakes firmly to slow from 45 MPH to 35 MPH, and the tractor immediately begins to skid with the trailer swinging to the right. The driver releases the brakes and counter-steers, but the trailer continues swinging until the combination reaches a full jackknife position. Which factor most likely initiated this jackknife sequence?

10. A tractor-semitrailer rolls over while negotiating an interstate highway curve at 50 MPH. Investigation reveals the following: the cargo was palletized goods loaded to the full height of the trailer (high center of gravity), the curve had an advisory speed of 35 MPH, the driver entered the curve at 50 MPH and did not brake until mid-curve, and the road surface was dry. Which combination of factors contributed most directly to this rollover?

11. A driver needs to uncouple a tractor from a semitrailer at a truck stop. Which step should be performed FIRST in the proper uncoupling sequence?

12. What is the purpose of the tractor protection valve in a combination vehicle’s air brake system?

13. A driver has coupled a tractor to a semitrailer and successfully performed the tug test. The fifth wheel is confirmed locked. What is the correct procedure for raising the landing gear before driving?

14. A driver notices that when applying the service brake pedal, the trailer seems to push against the tractor momentarily before the trailer brakes engage, causing a brief “surge” feeling. What does this symptom indicate about the brake system?

15. A driver operating a twin-trailer combination (doubles) is approaching a right turn onto a narrow two-lane road from a highway. The first trailer is 28 feet long and the second trailer is also 28 feet. Compared to a single 53-foot semitrailer, how does the off-tracking behavior differ for this doubles combination during the turn?

16. A new CDL driver is learning to couple a tractor to a semitrailer. The driver performs the following steps in this order: (1) backs under the trailer until the fifth wheel engages, (2) connects the air lines, (3) raises the landing gear, (4) performs the tug test, (5) connects the electrical cord. What is wrong with this sequence, and what risk does it create?

17. A driver operating a loaded tractor-semitrailer on a dry highway at 55 MPH encounters an emergency situation requiring immediate stopping. A passenger vehicle has crossed into the CMV’s lane from a perpendicular road. The driver has approximately 2 seconds before impact. Which braking technique provides the best chance of stopping safely while maintaining steering control?

18. During a pre-trip inspection of a Class A tractor-semitrailer, a driver examines the fifth wheel mounting and observes the following: the fifth wheel is securely bolted to the tractor frame with no missing fasteners, the fifth wheel plate has visible grease but shows a worn, dry streak along the center where the trailer kingpin slides, the locking jaw mechanism moves freely but has visible wear marks on the jaw surface, and the release lever operates correctly with the safety latch engaging. Which condition requires immediate correction before driving, and why?

19. A driver operating a triple-trailer combination (three 28-foot trailers) on a straight highway at 60 MPH needs to make a sudden lane change to avoid debris in the road. After the tractor moves into the adjacent lane, what happens to the trailing trailer units, and what risk does this create?

20. A driver couples a tractor to a semitrailer and performs all correct coupling steps including the tug test. During the subsequent pre-trip inspection, the driver checks the fifth wheel area and notices the locking lever is in the locked position with the safety latch/clip engaged, but the fifth wheel plate sits slightly higher than expected relative to the trailer frame, and there is a gap visible between the fifth wheel plate and the trailer’s kingpin plate. What is the most likely cause and what action should the driver take?

21. What is the correct sequence for the first two steps when coupling a tractor to a trailer?

22. What is the correct use of the trailer hand valve (trolley valve) during normal driving operations?

23. A driver has backed under a trailer and the fifth wheel has locked around the kingpin. Before raising the landing gear, what critical test must the driver perform?

24. Which combination of factors creates the HIGHEST risk for rollover in a combination vehicle?

25. A driver begins to notice the trailer drifting toward the shoulder on a curve. What is the correct response to prevent a potential rollover?

26. A driver is operating a combination vehicle on an icy road when the trailer begins to swing outward to the left (trailer jackknife). The driver’s initial instinct is to apply the brakes hard and steer right to correct. What should the driver actually do, and why?

27. During the coupling process, after backing under the trailer and hearing the fifth wheel lock, a driver notices the trailer landing gear is on soft ground. What is the correct procedure for the tug test in this situation?

28. A driver is hauling a tanker trailer partially filled with liquid. Which statement BEST explains why this configuration presents a higher rollover risk than a fully loaded tanker?

29. When uncoupling a tractor from a trailer, what should the driver do BEFORE lowering the landing gear?

30. A driver is operating a combination vehicle in strong crosswinds on an open highway. The trailer begins to sway side to side. The driver considers several responses. Which response would be MOST dangerous?

You are delivering a trailer to a loading dock where space is extremely limited. Before coupling, you should:

During your pre-trip inspection, you notice that the fifth wheel appears to have excessive wear but the trailer will couple. What should you do:

You’re approaching a steep downgrade with your combination vehicle fully loaded. What is your primary braking strategy:

When transporting placarded hazardous materials in a combination vehicle, how often should you inspect the cargo area:

You need to back a 53-foot trailer into a narrow loading dock that’s at a 45-degree angle to your approach. What technique should you use:

What is the maximum weight limit for a five-axle tractor-trailer combination on the federal interstate system:

Your trailer brakes fail during a descent on a mountain grade. Which action should be your FIRST priority:

Which component in the fifth wheel coupling system is designed to prevent accidental separation:

When hauling hazardous materials, what is the maximum on-duty period before taking a 10-hour break:

During your pre-trip inspection, you find that the trailer tandems are positioned to their rear-most setting. What potential safety issue does this create:

When coupling a tractor to a semi-trailer, after connecting the glad hands, you should press the trailer air supply valve and listen for:

During a pre-trip inspection of a combination vehicle, you notice the converter dolly air tank drain valve is continuously dripping air. After checking the valve is fully closed, the dripping persists. What is the most appropriate action?

When driving a double-trailer combination on a curved highway off-ramp, the rear trailer will follow a path that is:

What is the minimum recommended following distance for a 65-foot combination vehicle traveling at 55 mph on dry pavement?

Before uncoupling a trailer, you should lower the landing gear until it:

What is the purpose of the tractor protection valve in a combination vehicle’s air brake system?

While driving a tractor-semitrailer combination downhill on a 6% grade, you need to maintain 35 mph. Your current speed is 40 mph and increasing. What is the most effective braking technique combination?

You’re driving a 53-foot trailer combination and need to make a right turn from a two-lane road onto another two-lane road. The intersection has a curb radius of approximately 20 feet. What is the best approach?

What is the primary danger of the “crack-the-whip” effect in double and triple trailers?

After coupling a tractor to a semi-trailer, you perform a tug test by driving forward slightly with the trailer brakes locked. The tractor moves but the trailer doesn’t. However, you notice the fifth wheel jaws are not fully visible through the sight window. What should you do?

While coupling a trailer with a sliding fifth wheel, you have positioned the tractor to align the kingpin with the fifth wheel. What is the critical safety procedure you must perform BEFORE engaging the fifth wheel locking mechanism?

During a pre-trip inspection of a tractor-trailer combination, you notice the trailer brakes are engaging earlier than the tractor brakes when applying the brake pedal gradually. What potential safety hazard does this indicate and what corrective action should you take?

You are operating a double-bottom tanker combination on a downhill grade when you notice significant surge from the front tank affecting the vehicle handling. What is the most effective driving technique to manage this situation?

After coupling a trailer to a tractor, you discover that the fifth wheel has a slight gap between the tractor and trailer frame despite the kingpin being fully engaged. What is the most immediate safety concern and what action should you take?

What is the primary reason why vehicle handling characteristics differ significantly between loaded and empty trailer combinations?

During a brake application on a fully loaded combination vehicle, you observe the trailer brakes locking up before the tractor brakes. What is the immediate danger and what corrective action should you take?

You are uncoupling a trailer in a confined space with limited clearance. What sequence of actions should you follow to ensure safe uncoupling and prevent damage to the equipment?

You are operating a combination vehicle in high crosswind conditions. What specific technique should you employ to maintain control and prevent trailer sway?

During a comprehensive pre-trip inspection, you notice the slack adjusters on the trailer brakes have more than 1/4 inch of play when the brakes are applied. What does this indicate and what immediate action should you take?

While driving a combination vehicle, you experience a sudden loss of air pressure in the trailer brake system while maintaining normal tractor brake pressure. What is the most appropriate immediate action to take?

When performing a pre-trip inspection of a combination vehicle, what should you check to ensure the fifth wheel is properly positioned and lubricated?

How does the trailer air supply valve (trailer glad hand) typically differ from the tractor supply line?

When backing a trailer with a tractor-trailer combination into a tight loading dock, which technique should you use to maintain control and prevent jackknifing?

If a combination vehicle is overweight on the trailer axles but within legal limits for the tractor axles, which adjustment should you make to properly distribute the weight?

When coupling a semi-trailer to a tractor, what is the proper procedure after connecting the air lines?

When descending a steep grade in a combination vehicle, which technique is most effective for maintaining safe speed and brake system integrity?

If the trailer breaks away from the tractor while traveling at highway speed, what should be your first action to maintain control?

When uncoupling a semi-trailer from a tractor, what safety equipment must you have in place before removing the fifth wheel locking pin?

A combination vehicle has a total weight of 80,000 pounds with the following axle weights: tractor steer axle: 12,000 lbs, tractor drive axles: 34,000 lbs, trailer tandems: 34,000 lbs. If you need to move 5,000 pounds of cargo forward in the trailer by 10 feet, how will this affect the axle weight distribution?

When connecting glad hands to a trailer’s air lines, what should you do if you observe damage to the rubber seal on one of the glad hands?

After coupling the tractor to the trailer, what is the purpose of pulling the tractor forward gently with the trailer brakes locked before completing the coupling process?

You are driving a tractor-trailer on a downhill grade and notice the trailer has begun to push the tractor, causing a jackknife risk. Which corrective action should you take first?

What would happen if the emergency (supply) air line between the tractor and trailer were to separate or rupture while driving at highway speed?

You are approaching a right turn at an intersection in a 53-foot trailer combination. The intersection is narrow with a curb on the right side. What is the safest turning technique?

During the pre-trip inspection of a combination vehicle, what should you check regarding the glad hand connectors and their rubber seals?

A tractor-trailer enters a curve too fast and the rear of the tractor begins to slide outward while the trailer remains relatively stable. What is happening, and what should the driver do?

During a pre-trip inspection, you notice that the fifth wheel sliding mechanism’s locking pins are worn and do not fully engage the slider rail holes. What is the correct action?

Why does a combination vehicle (tractor-trailer) have a greater risk of rollover compared to a single-unit truck of the same weight?

While driving on an interstate at 60 mph, your trailer begins to swing out to the left in a trailer jackknife. You have already released the accelerator. What is your next immediate action?

A driver is preparing a fully loaded combination vehicle for a 500-mile trip through mixed terrain including mountain grades. During the pre-trip inspection, all mechanical systems check out. Which additional factor is most critical to safe operation in mountainous terrain that the driver must verify before departure?