Colorado DMV CDL General Knowledge Practice Test 7
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
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1. What does the commercial driver manual tell you to do with the parking brake when you leave your vehicle?
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Answer B: Apply the parking brake every time you leave the vehicle
The manual is explicit that the parking brake goes on whenever the driver leaves the vehicle, because once nobody is at the controls it is the only thing holding it.
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2. An oncoming vehicle at night has bright headlights that are making it hard to see. What should you do?
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Answer B: Look toward the right edge of your lane and avoid looking directly at the lights
Looking at the right edge of the road keeps your eyes off the glare while you stay in your lane; glare can leave you nearly blind for several seconds.
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3. Unless otherwise posted, what speed limit does Colorado set for vehicles in the business of hauling trash?
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Answer D: 45 mph
Colorado's published list of statutory speed limits includes 45 mph for vehicles in the business of hauling trash.
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4. What is checked in step six of the seven-step method?
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Answer D: The turn signals and the stop lights, checked from outside the vehicle
Step six returns to the cab to switch on the signal and stop lamps, then checks each one from outside, because those lamps are not lit during the earlier light check.
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5. Federal rules keep recapped and retreaded tires off the front wheels of which vehicle?
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Answer B: Any bus carrying passengers
The federal rule names buses: a bus may not run with regrooved, recapped or retreaded tires on its front wheels, because a steer tire failure with passengers aboard takes away steering control.
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6. Why should you avoid using your lights to tell a following driver that it is safe to pass you?
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Answer B: You may misjudge the gap and the driver will act on your signal
The manual warns against signaling others to pass, because the responsibility for a head-on crash then rests on a judgment you could easily get wrong.
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7. During the walkaround you find the reflective conspicuity tape along the trailer caked with road grime. What should you do?
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Answer B: Clean it, because dirty reflective material cannot make the trailer visible at night
Reflective sheeting only works if light can reach it and bounce back, so a dirty strip leaves the trailer effectively unmarked to approaching traffic.
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8. On a tractor with a sliding fifth wheel, what does moving the fifth wheel forward do?
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Answer A: Puts more of the trailer weight onto the steering axle
Moving the coupling point forward transfers weight from the drive axles to the steering axle, which is how a driver corrects a drive axle that is over the limit.
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9. Why must cargo also be held down against vertical movement and not only against sliding?
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Answer D: Because a load that bounces can jump the blocking and slacken its own tiedowns
Rough road makes an unrestrained article lift; every bounce lets it move a little and works the tiedowns loose until nothing is holding it.
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10. What happens to braking performance if oil or grease reaches a brake lining?
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Answer B: That brake loses much of its effect and the vehicle can pull to one side
A contaminated lining cannot grip the drum, so that wheel contributes little braking and the vehicle pulls toward the side that is still working.
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11. In the seven-step method, what comes immediately after starting the engine and inspecting inside the cab?
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Answer D: Turn off the engine and check the lights
Step four shuts the engine down and switches on the lamps needed for driving so the driver can leave the cab and confirm they actually work.
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12. Your axle weights are legal, but the tires on that axle are rated below the weight it is carrying. What controls?
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Answer B: The lower figure, so the tires may not be loaded beyond their marked rating
You may never exceed the rating marked on a tire, even when the axle limit would allow more, because an overloaded tire builds heat and can fail.
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13. Which set of maneuvers makes up the basic control skills part of the commercial driving test?
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Answer D: Straight line backing, offset backing, parallel parking and alley docking
The basic control skills test is carried out off the road and consists of low speed exercises such as straight line backing, offset backing, parallel parking and the alley dock.
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14. You are told a posted bridge ahead has a weight limit lower than your gross weight. What must you do?
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Answer C: Take a route that avoids it, because a posted limit is a legal limit
A posted structure limit must be obeyed exactly as any other weight limit, so a heavier vehicle has to be routed around it.
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15. A hazard suddenly appears ahead and you must act. Which is usually the faster way to avoid it in a heavy vehicle?
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Answer B: Steering around it, because you can usually turn faster than you can stop
Stopping distance at speed is very long, so a quick turn out of the way, when there is room, avoids the crash sooner than braking.
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16. When should a driver select the gear for a long, steep downgrade?
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Answer B: Before starting down the grade
The low gear has to be chosen before the descent, because a heavy vehicle gaining speed may refuse to shift down at all.
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17. What tells you that an air suspension bag has a problem?
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Answer B: The bag is leaking or damaged, or the vehicle sits unevenly on that side
An air bag that leaks or is cut lets that corner of the vehicle settle, which throws the load onto the other suspension parts and changes the ride height.
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18. What are you looking for on the brake drums during the walkaround?
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Answer B: Cracks, dents and any oil or grease that has reached the friction surface
A cracked or badly scored drum can break apart under braking heat, and oil or grease on the friction surface destroys the braking effort at that wheel.
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19. Why should the radiator cap never be removed while the engine is hot?
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Answer A: The cooling system is under pressure and scalding coolant can be sprayed out
A hot cooling system holds pressurized coolant above its normal boiling point, so releasing the cap can throw boiling liquid and steam at whoever is holding it.
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20. Why does a driver use pull-ups while backing into a tight space?
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Answer C: To pull forward and start the approach again when the angle is going wrong
Stopping, pulling ahead and repositioning fixes a bad angle safely, and there is nothing wrong with needing more than one attempt.
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21. What extinguisher rating is required on a vehicle carrying hazardous materials in amounts that need placards?
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Answer B: 10 B:C or more
Placarded loads carry a much higher fire risk, so the required extinguisher rating rises to at least 10 B:C.
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22. You are about to slow down sharply on a highway to make a turn into a narrow driveway. How can you warn the drivers behind you?
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Answer C: Tap the brake pedal a few times so the brake lights flash before you slow down
A few light taps flash the brake lights and give following drivers an early warning that you are about to slow or stop.
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23. A car that passed you on the right slows and stays alongside your trailer. What is the best response?
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Answer D: Ease off the accelerator so the car can move clear
A vehicle sitting beside a trailer is in a blind area and has nowhere to go if you need the lane, so the safest fix is to let it get ahead or behind.
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24. During the walkaround you notice one tire on an axle is a radial and the tire next to it is bias-ply. What should you do?
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Answer B: Treat it as a defect, because radial and bias-ply tires must not be mixed on the same axle
Radial and bias-ply tires flex and grip differently, so mixing them on one axle makes the vehicle handle unpredictably and is not allowed.
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25. You have a part load that fills only a third of a long trailer. How should it be placed?
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Answer C: Spread out and centerd side to side, so the weight sits over the axles
A part load is spread over as much of the floor as possible and kept centerd, so no axle is overloaded and the vehicle stays balanced from side to side.
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26. Experienced commercial drivers scan the road ahead by roughly how much travel time?
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Answer B: About 12 to 15 seconds
Looking 12 to 15 seconds ahead gives a heavy vehicle enough room to slow or change lanes smoothly instead of reacting late.
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27. Your windshield washer reservoir is empty and rain and road spray are expected. What should you do?
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Answer D: Fill it before the trip, because you need the washers to keep the windshield clear
Wipers alone smear the film of oil and grit thrown up by traffic, so the washers are part of keeping a usable view of the road.
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28. If an intersection has two lanes marked for left turns, which one should a large vehicle use?
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Answer D: The right hand of the two turning lanes
The outside turning lane leaves room for the rear of the vehicle to swing without striking a vehicle in the adjacent lane.
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29. The coolant temperature gauge climbs above its normal range on a long grade. What is the correct response?
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Answer C: Stop when it is safe to do so and find the cause before going on
Rising coolant temperature signals a fault such as a lost belt, a leak or a blocked radiator, and continuing can turn a repair into a destroyed engine.
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30. A vehicle becomes unsafe while you are already on the road. What does the federal rule allow?
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Answer A: Continuing only to the nearest place where repairs can safely be made
If stopping where you are would be more dangerous than moving, the rule allows you to reach the nearest place where the vehicle can safely be repaired, and no further.
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31. Does the federal texting ban apply to a company dispatching device mounted in the cab?
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Answer B: Yes, entering or reading text on it while driving is banned
The rule is written around the act of reading or entering text on any electronic device, not around who owns the device.
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32. An angry driver has cut in front of you and is now braking hard to provoke you. What is the safest response?
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Answer D: Drop back, avoid eye contact and let the driver go
Giving an aggressive driver space and no response removes the conflict, while any answering gesture invites escalation you cannot control in a heavy vehicle.
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33. Where on the road are you most likely to find ice in cold weather?
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Answer B: On bridges, overpasses and shaded stretches, which freeze before the rest of the road
Bridges and overpasses lose heat from above and below, and shaded areas get no sun, so they ice over first and stay icy longest.
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34. What must be checked about the cargo doors and any tarpaulin before a trip?
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Answer B: That the doors are closed and latched and that any tarp is tied down securely
An unlatched door or a loose tarp can swing open or tear free at speed, spilling cargo or blocking the view of the traffic behind you.
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35. Which factors determine a safe speed for a long, steep downgrade?
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Answer C: The steepness and length of the grade, the weight of the vehicle and cargo, and the road and weather conditions
Gravity, weight and traction all decide how fast a heavy vehicle can safely descend, which is why signs often post lower speeds for trucks on grades.
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36. What must the driver confirm about the required emergency equipment before a trip?
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Answer A: That it is in place, in working order and ready to be used
Federal rules require the driver to be satisfied that the emergency equipment is present and ready, because it is needed at the worst possible moment.
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37. Your vehicle begins to hydroplane on a wet road. What should you do?
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Answer B: Release the accelerator and push in the clutch so the wheels can turn freely and regain grip
Hydroplaning tires are riding on water; slowing without braking lets them settle back onto the road and grip again.
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38. How are the extra gears of a multi-speed rear axle or auxiliary transmission usually controlled?
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Answer D: With a selector knob or switch on the gearshift lever of the main transmission
A range selector on the shift lever lets the driver choose the extra gear range while shifting the main transmission.
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39. You pick up a trailer that another driver dropped in the yard. What must you do before pulling it?
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Answer B: Inspect it yourself, because you are responsible for the whole vehicle you drive
Responsibility follows the driver who moves the vehicle, and a trailer that has stood in a yard may have lost air, developed a flat tire or been damaged.
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40. Why does the manual insist on a firm grip with both hands on opposite sides of the steering wheel?
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Answer A: A hard bump can pull the wheel out of a loose grip
Hitting a curb or a deep pothole can jerk the wheel violently, and only a firm two-handed grip keeps the vehicle under control when that happens.
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41. Which of these is NOT on the federal list of parts and accessories the driver must be satisfied are in good working order before driving?
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Answer D: The seat cushion upholstery
The federal pre-trip rule names brakes, steering, lights and reflectors, tires, horn, wipers, mirrors, coupling devices, wheels and rims, and emergency equipment; seat upholstery is not on that list.
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42. A fire has started in the vehicle. How should the extinguisher be used?
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Answer B: Stay as far back as the reach of the extinguisher allows, stand upwind, and aim at the base of the fire
Aiming at the base attacks what is actually burning, and staying upwind and well back protects the driver from heat, smoke and the flames themselves.
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43. Which windshield condition should be reported during the inspection?
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Answer B: Cracks or dirt that get in the way of your view of the road
The windshield must give a clear view; damage or grime in the driver line of sight is a safety defect.
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44. The engine oil pressure gauge falls toward zero while you are driving. What should you do?
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Answer C: Stop as soon as it is safe to do so and shut the engine down
Loss of oil pressure destroys an engine in a very short time, so the correct response is to stop and shut down rather than to drive on.
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45. A 40 foot straight truck and a 70 foot tractor-trailer make the same right turn. Which needs more room and why?
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Answer B: The tractor-trailer, because the longer the vehicle the farther inside the rear wheels track
Off-tracking grows with the distance between the front and rear axles, so the longer combination cuts the corner much more sharply and needs extra room.
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46. Loading heavy freight on top of lighter freight has what effect on the vehicle?
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Answer B: It raises the center of gravity and makes a rollover more likely
A high center of gravity lets the vehicle tip more easily in curves or during a sudden swerve.
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47. What does a front-end header board on a van or flatbed protect against?
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Answer A: Cargo moving forward toward the cab in a crash or hard stop
The header board, often called a headache rack, blocks forward movement of the load toward the driver.
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48. During the walkaround inspection, where does the driver normally start and how does the check proceed?
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Answer C: At the left front of the vehicle, working around it in a set order that returns to the cab
The walkaround follows the same route every time, starting at the left front and circling the vehicle, so that nothing is skipped when the driver is tired or rushed.
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49. How do you test for leaks in a hydraulic brake system during the pre-trip inspection?
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Answer A: Pump the pedal three times, then hold firm pressure for five seconds and make sure the pedal does not move
If the pedal sinks while you hold pressure, fluid is escaping or air is in the lines, and the vehicle must not be driven until the problem is repaired.
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50. How does a front tire failure usually feel to the driver?
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Answer D: The steering suddenly becomes heavy and pulls to one side
A failed front tire loads the steering and makes the wheel feel heavy, while a rear tire failure shows up as the back end swaying.