Texas CDL: General Knowledge Practice Test

Not quite. The answer is You can use the tachometer to tell you when to shift.

You can use your tachometer to determine when to upshift. Before driving your vehicle, check the driver's manual to find out the recommended operating rpm range. As you're driving, keep your eye on your tachometer as your vehicle increases speed. Upshift when engine rpm gets high enough. Double-clutching is a technique used mostly for shifting gears in an unsynchronized manual transmission, such as those found on some trucks. This technique helps you manually match engine speed to the speed of the gear you'll shift into. (A synchronized manual transmission matches the speed for you.)

Not quite. The answer is Allow injured persons to become chilled or overheated.

If qualified medical personnel are at the accident scene, stay out of their way unless they ask for help. If they haven't arrived yet, try to keep injured persons warm (but not overheated) or cool (but not chilled). Don't move them unless there is a danger of fire or another accident from passing traffic.

Not quite. The answer is A burning tire should be cooled with water.

If the cargo is on fire, opening the trailer's doors will let more oxygen into the trailer and feed the fire. If a tire is on fire, it should be cooled, preferably with a lot of water.

Not quite. The answer is 250 feet ahead.

Your low beams let you see about 250 feet ahead. Your high beams let you see about 350–500 feet ahead.

Not quite. The answer is All of the above are true.

49% of CMV drivers smoke, compared with 27% of the general adult population. 73% of CMV drivers are obese, compared with 33% of the general population. 33% of CMV drivers have hypertension (high blood pressure), compared with 26% of the general population. Finally, only 8% of CMV drivers exercise regularly, compared with 25% of the general population.

Not quite. The answer is Release the brake when you are 5 mph below your safe speed and let your speed come back up to your safe speed. Then repeat braking to 5 mph below your safe speed.

The best technique for descending is to assess the slope and conditions and choose a safe speed. Once you reach this speed, gently brake until you are going 5 miles an hour slower, and then let your speed build up again. When you reach your safe speed, brake again, and so forth. This is much less likely overheat your brakes than trying to hold a set speed with the brakes permanently half on.

Not quite. The answer is When going down grades

To use engine braking on a downgrade to control the speed of a CMV with an automatic transmission, select a low gear range that prevents the transmission from shifting up beyond the selected gear.

Not quite. The answer is Protect the accident scene.

At an accident scene, first protect the accident scene to help prevent another accident. Pull your vehicle as far away from traffic and as close to the side of the road as possible. Set out warning devices such as reflective triangles.

Not quite. The answer is The cargo you're carrying makes stopping mandatory under federal or state regulations.

A full stop is required at railroad grade crossings whenever (a) the nature of the cargo makes a stop mandatory under state or federal regulations, or (b) such a stop is otherwise required by law. For example, federal regulations require any CMV that is placarded for carrying hazardous materials to stop at every railroad grade crossing.

Not quite. The answer is Make sure the oil pressure gauge is working.

When you start the engine, the oil pressure shown on the gauge should rise to normal oil pressure or the warning light should turn off.

Not quite. The answer is If you stop on a hill or curve, it's necessary to place them up to 500 feet behind your vehicle.

Under federal regulation 49 CFR 392.22, if you must stop your CMV in an emergency at night or when visibility is low, you must turn on your four-way hazard flashers, AND you must set out your emergency warning devices (flares, fusees, or reflective triangles) within 10 minutes. That same regulation also states where you must place your emergency warning devices. If your vehicle is stopped within 500 feet of a curve, a crest of a hill, or another obstruction to viewing, you must place a warning device within 100–500 feet of your vehicle, in the direction of that obstruction.

Not quite. The answer is There are blind spots you can't see.

If you can, use a helper when backing up. Even with all your mirrors, there are still blind spots that you cannot see. The helper can stand near the rear of your vehicle and keep an eye on your blind spots. He or she can signal you to stop before an accident can occur.

Not quite. The answer is At night, keep your high beams on as you pass the vehicle.

Whenever you are about to pass a vehicle, pedestrian, or bicyclist, assume they don't see you. They could suddenly move in front of you. Where it is legal, tap the horn lightly or, at night, flash your lights momentarily from low beams to high beams and back. (High beams can be distracting or even blinding if left on.)

Not quite. The answer is provide enough traction to steer and push the vehicle through snow.

Snow-covered road surfaces provide much less traction than dry surfaces. Your tires must provide enough traction to maneuver your vehicle on snow safely. Under federal regulations, your front tires must have a tread depth of at least 4/32 inch, and all other tires must have a tread depth of at least 2/32 inch. For best traction, however, make sure that the treads are even deeper before you try to drive on snow.

Source: 49 CFR 570.62

Not quite. The answer is The length of a football field

For a tractor-trailer traveling at 55 mph on dry pavement, the typical perception distance is about 142 feet, the typical reaction distance is about 61 feet, and the typical braking distance is about 216 feet, for a total stopping distance of 419 feet. Air brake lag distance adds another 32 feet to this total. In comparison, the length of a football field (including the two end zones) is 360 feet.

Not quite. The answer is All of the above

If you must drive through a tunnel, there are several issues you must deal with. First, make sure that the tunnel is tall enough for your vehicle to get through it safely. Plan in advance. Know the height of your CMV and the height of the tunnel ceiling. Second, tunnels often have reduced lane widths. Your CMV may be 8½ feet wide. Drive with caution and watch the sides of your vehicle. Finally, there can be strong winds inside the tunnel, and strong crosswinds as you exit the tunnel.

Not quite. The answer is Use engine speed (rpm) and road speed (mph).

Before driving your vehicle, check the driver's manual to find out the recommended operating rpm range. As you're driving, keep your eye on your tachometer as your vehicle increases speed. Shift up when engine rpm gets to the top of the recommended range. Another way to know when to shift up is to learn in advance which gears are suited to which speeds. As you drive, watch your speedometer and shift accordingly.

Not quite. The answer is Main spring

Component R is a main leaf spring. Component U is an auxiliary leaf spring (sometimes called a helper spring), attached to the axle with the same U-bolt. Auxiliary springs are often employed in rear suspensions that have to support heavy loads.

Not quite. The answer is use a lower gear than you would use to climb the hill.

With older trucks, you typically use the same gear for driving uphill and driving downhill. Today's trucks tend to have more powerful engines and be more efficient than older trucks. Hence, you can drive such a truck uphill in higher gears than you would use to drive downhill with engine braking.

Not quite. The answer is release the parking brake as you apply engine power.

If you start to move your vehicle when facing uphill, you need to take steps to keep from rolling back. If your vehicle has a manual transmission, partly engage the clutch before you take your right foot off the brake. Put on the parking brake whenever necessary to keep from rolling back. Release the parking brake only when you have applied enough engine power to keep from rolling back. On a tractor-trailer equipped with a trailer brake hand valve, the hand valve can be applied to keep from rolling back until you've built up engine power.