Colorado DMV CDL General Knowledge Practice Test 10
- Questions50
- Correct to pass40
- Passing score80%
- Minimum age18 years
-
1. You hear air escaping from a trailer tire during the pre-trip. What should you do?
Show answer
Answer C: Have it repaired or replaced before the vehicle is driven
An audible leak means the tire is failing now, and federal rules do not allow a vehicle to be operated on a flat or leaking tire.
-
2. Why is driving much slower than the rest of the traffic dangerous?
Show answer
Answer B: Other drivers must keep passing you, which creates conflicts
Traffic that has to work its way around you produces lane changes and closing speeds, which is why a large speed difference is itself a hazard.
-
3. How is free play in the steering wheel measured during the inspection?
Show answer
Answer B: By turning the wheel until the front wheels just start to move and noting the movement
Play is the movement at the rim that produces no movement at the road wheels, so it is measured by turning until the wheels first respond.
-
4. What are you checking when you look at the batteries during the engine compartment inspection?
Show answer
Answer D: That they are securely mounted, the connections are tight and free of corrosion, and the caps are in place
Loose or corroded batteries can fail or short out, so the mount, cables, terminals and vent caps are all part of the check.
-
5. Which set of emergency equipment must be carried on a commercial motor vehicle?
Show answer
Answer D: A fire extinguisher, spare electrical fuses unless the vehicle has circuit breakers, and warning devices
The required kit is a properly charged and rated fire extinguisher, spare fuses when the vehicle uses them, and warning devices for a stopped vehicle.
-
6. May a commercial driver use a hand-held phone while stopped at a red light?
Show answer
Answer B: No, a stop in traffic still counts as driving
Hand-held use is allowed only when the vehicle has been moved to the side of or off the highway and halted where it can safely remain stopped.
-
7. You find a defect during the pre-trip inspection. What must happen before the vehicle is driven?
Show answer
Answer C: It must be repaired, or the vehicle must not be driven
Writing a defect down does not make the vehicle safe; a defect that affects safe operation has to be corrected before the trip starts.
-
8. You are backing into a yard where electrical wires cross overhead. What is the main concern?
Show answer
Answer C: The wires may hang lower than the top of your vehicle
Overhead space has to be checked like any other space around the vehicle, because wires and cables are often lower than they look from the cab.
-
9. You can see a crack in a brake drum that runs across more than half the width of the friction surface. What does this mean?
Show answer
Answer C: The drum is defective and must be repaired before the vehicle is driven
Cracks longer than half the width of the friction area mean the drum can break apart under braking heat and must be replaced.
-
10. For an unblocked article longer than 10 feet, the minimum is two tiedowns plus how many more?
Show answer
Answer B: One more for every additional 10 feet of length or any part of 10 feet
Past the first 10 feet, one more tiedown is added for each additional 10 feet of length or any fraction of that distance.
-
11. An article of cargo has been blocked so that it cannot move forward. How many tiedowns does the federal rule call for?
Show answer
Answer A: One tiedown for every 10 feet of article length, or any part of that
Blocking against forward movement lowers the requirement to one tiedown per 10 feet of length or fraction of 10 feet.
-
12. Why should a driver avoid traveling alongside another vehicle for any length of time?
Show answer
Answer D: You lose your escape route and you may be sitting in the other driver blind spot
Running beside someone leaves nowhere to move if you have to change lanes, and the other driver may not know you are there at all.
-
13. What is checked about the clutch and the gearshift during the in-cab inspection?
Show answer
Answer D: That the clutch free play is within the range the manufacturer specifies
Too little or too much clutch free play causes slipping or dragging, either of which can leave the driver unable to select the gear a hill demands.
-
14. What are you checking on the mud flaps during the walkaround?
Show answer
Answer C: That they are securely attached, not torn and not dragging on the ground
A flap that is torn or hanging loose stops shielding following traffic from spray and stones, and a dragging flap can catch and tear away on the road.
-
15. Who may remove an out-of-service sticker from a commercial vehicle?
Show answer
Answer B: Only an authorized person, and only after the defect that caused it has been repaired
The sticker stays on the vehicle until the repairs are made and an authorized person removes it, so nobody can simply peel it off and drive away.
-
16. On a multilane highway, which lane should a heavy vehicle normally use?
Show answer
Answer A: The right lane, except to pass or where signs direct otherwise
Keeping right leaves the faster lanes free and reduces the number of vehicles that have to move around a slower, heavier vehicle.
-
17. Cargo securement must be strong enough to hold the load under which conditions?
Show answer
Answer A: Hard braking, hard acceleration and hard turning, as well as the bouncing of the road
The securement standard is written around the forces of a hard stop, a hard start, a hard turn and vertical movement on a rough surface, all of which occur in ordinary driving.
-
18. How does bracing differ from blocking when securing cargo?
Show answer
Answer B: Bracing runs from the upper part of the cargo to the floor or walls to keep it from moving, while blocking fits snugly against the cargo
Blocking is shaped to fit against the front, back or sides of a piece of cargo; bracing supports it from above so it cannot tip or shift.
-
19. After coupling, where should the fifth wheel release handle be?
Show answer
Answer A: In the locked position with the safety latch in place
The handle must be pushed in and latched, because a handle left out means the jaws can open and release the trailer while you are driving.
-
20. Why is cargo often covered with a tarp?
Show answer
Answer C: To protect people from spilled cargo and to protect the cargo from weather
A cover keeps material from blowing or spilling onto the road and shields the load from rain and sun; it does not replace securement.
-
21. You are backing a tractor-trailer in a straight line and the trailer starts to drift to the left. What is the standard correction?
Show answer
Answer D: Turn the top of the steering wheel a little to the left, toward the drift
Small corrections made in the direction the trailer is drifting bring it back into line; large or opposite movements make the drift worse.
-
22. Which combination of warning devices meets the requirement for a stopped commercial vehicle?
Show answer
Answer A: Three reflective triangles, or six fusees, or three liquid burning flares
A vehicle may carry three bidirectional reflective triangles, six fusees or three liquid burning flares as its warning devices.
-
23. Your load projects more than 4 feet beyond the rear of the vehicle. How must the projecting end be marked?
Show answer
Answer A: With a red or orange flag by day and a red lamp after dark
Federal rules require a warning flag on a rear projecting load in daylight and a red lamp on the end of it when lights are required.
-
24. What condition should the fifth wheel be in before you back under a trailer?
Show answer
Answer C: Jaws open, plate greased, and the fifth wheel tilted down toward the rear
The jaws have to be open to take the kingpin, the plate must be lubricated to prevent hard steering, and the fifth wheel is tilted down at the rear so the trailer apron can ride up onto it.
-
25. Your brakes have failed and you decide to use the parking brake to slow down. Why should you hold the release button or lever while doing so?
Show answer
Answer D: So you can release the brake at once if the wheels lock and the vehicle starts to skid
The parking brake can lock the wheels; keeping your hand on the release lets you let go the moment a skid starts and regain control.
-
26. What are the rules for using your turn signal before a turn or lane change?
Show answer
Answer A: Signal early, keep the signal on until the turn is finished, then cancel it
An early, continuous signal tells others what you plan to do; cancelling afterward keeps the signal from misleading them.
-
27. Why should a driver avoid stopping partway up a snow covered hill?
Show answer
Answer D: You may not get moving again and could slide backwards
On a slippery grade the drive wheels may simply spin when you try to restart, leaving the vehicle stuck across the road or sliding back down it.
-
28. Which step of the seven-step inspection method comes immediately after checking the engine compartment?
Show answer
Answer D: Start the engine and inspect the inside of the cab
Once the hood is closed the driver moves to the driver seat, starts the engine and checks gauges, controls and warning devices before going any further.
-
29. On a set of dual tires, which condition must be reported as a defect?
Show answer
Answer D: The two tires are touching each other or rubbing on part of the vehicle
Duals that touch each other or the vehicle overheat and wear quickly, so they must be separated by proper spacing and inflation before driving.
-
30. On a one way street or a divided highway, where are the warning devices placed?
Show answer
Answer B: About 10 feet, 100 feet and 200 feet back toward the approaching traffic
When traffic can only come from one side, all three devices are spread out behind the vehicle to give approaching drivers a longer warning.
-
31. A driver snores heavily, stops breathing briefly during the night and is tired all day despite long hours in bed. What should be suspected?
Show answer
Answer B: Sleep apnea
Sleep apnea repeatedly interrupts breathing during sleep, so the driver never gets true rest and stays dangerously drowsy during the day.
-
32. You have countersteered to correct a rear-wheel skid and the vehicle straightens out. What must you be ready for next?
Show answer
Answer D: The vehicle may swing back the other way, so you must steer again to correct it
A vehicle coming out of a skid tends to overshoot and swing in the opposite direction, and the driver must be ready to countersteer a second time.
-
33. Why does a load of live animals need special attention?
Show answer
Answer D: The animals move and lean, so the center of gravity shifts and the vehicle can be pushed off balance in a turn
A live load will not stay where it is put, and that movement changes the balance of the vehicle exactly when a curve is loading it most.
-
34. You are entering a freeway from a short ramp with a fully loaded trailer. What should you do?
Show answer
Answer A: Begin building speed early and wait for a large gap
A loaded vehicle accelerates slowly, so it needs both a running start and a much larger gap than a car would use.
-
35. How does the working load limit of a tiedown relate to the force that would break it?
Show answer
Answer B: The working load limit is a fraction of the breaking strength and is the figure you use
The working load limit is set well below the point at which the device would fail, and securement is always calculated from the working load limit, never from breaking strength.
-
36. Which description matches controlled braking during an emergency stop?
Show answer
Answer D: Apply the brakes as hard as you can without locking the wheels and keep steering movements small
Controlled braking keeps the wheels rolling just short of lockup, which gives the shortest stop while you keep the ability to steer.
-
37. What is wrong with resting your foot on the clutch pedal between shifts?
Show answer
Answer B: It slowly wears the clutch out, because the pressure plate is never fully engaged
Any weight on the pedal partly disengages the clutch, so it slips and wears; the foot belongs off the pedal once the shift is finished.
-
38. You must leave the vehicle parked on a slight grade. What adds security beyond setting the parking brake?
Show answer
Answer D: Chocking the wheels so the vehicle cannot roll if the brake bleeds off
Chocks hold the vehicle mechanically and are the standard backup whenever a parked vehicle could roll.
-
39. What is the best practice when fog is thick enough to hide the road ahead?
Show answer
Answer B: Slow down before entering the fog, and if visibility is too poor, pull off into a rest area or truck stop until it improves
The safest choice in heavy fog is not to be driving in it, and if you are already in it your speed has to come down before your visibility does.
-
40. Which lamp must make the rear registration plate legible after dark?
Show answer
Answer C: A white lamp that lights the plate
A white license plate lamp is required so the plate can be read at night, and a burned out one is a defect like any other lamp.
-
41. What does the suspension system weight rating tell the driver?
Show answer
Answer A: The maximum weight that the manufacturer says the suspension can carry
Like tires and axles, suspensions have a manufacturer capacity, and loading beyond it can damage springs and air bags.
-
42. Why must you never coast down a hill in neutral or with the clutch pushed in?
Show answer
Answer C: You lose the braking effect of the engine and your brakes may overheat and fail
Engine braking is what keeps a heavy vehicle in check on a grade; coasting throws it away and leaves the service brakes to do all the work until they overheat.
-
43. How long must a Colorado commercial learner's permit be held before the skills test may be taken?
Show answer
Answer B: 14 calendar days
Colorado requires the commercial learner's permit to be held for 14 calendar days before the skills test can be taken at an approved third-party testing facility.
-
44. What should you do before backing into a space you have not used before?
Show answer
Answer A: Get out and walk around to check the path, the clearance and any obstacles
Walking the area first reveals low obstructions, soft ground and objects that never appear in the mirrors.
-
45. What is the basic rule about backing a large vehicle?
Show answer
Answer B: Avoid backing whenever there is another way
Backing is dangerous because you cannot see everything behind you, so the manual tells drivers to plan routes and parking that avoid it.
-
46. What should you do with the previous driver vehicle inspection report before starting your trip?
Show answer
Answer B: Review it and confirm that listed defects were certified as repaired or as not needing repair
Reviewing the last report and the carrier certification tells you whether reported defects have been corrected before you take the vehicle out.
-
47. What is the purpose of the header board, or headache rack, that you inspect behind the cab?
Show answer
Answer A: It protects the driver from cargo that shifts forward during a hard stop
In a hard stop the load keeps moving forward, and the header board is the barrier between that load and the back of the cab.
-
48. Your drive wheels start to spin and the rear begins to slide while you accelerate on a slick surface. What should you do?
Show answer
Answer B: Stop accelerating and, if the vehicle has a manual transmission, push in the clutch
An acceleration skid ends when the drive wheels stop pushing, so easing off the throttle and disengaging the clutch lets them regain grip.
-
49. What should the ammeter or voltmeter show once the engine is running?
Show answer
Answer D: A reading in the normal charging range
With the engine running, the alternator should be charging; a discharge reading or an abnormal charge level means an electrical fault.
-
50. How can a driver restart the 60 or 70 hour on-duty limit?
Show answer
Answer B: Take 34 or more consecutive hours off duty
A period of 34 or more consecutive hours off duty resets the 60 or 70 hour calculation so the driver can begin a new period.