NV CDL General Knowledge common mistakes
NV CDL General Knowledge · Understand the traps and how to avoid them.
Treating the air-brake warning buzzer as a signal to keep driving to the next stop, instead of stopping and investigating once the low-pressure warning activates (typically around 60 psi) and the spring brakes have not yet applied.
Candidates memorize the 100 psi operating range and the governor cut-in/cut-out numbers but never learn the sequence of what happens as pressure falls, so they misread the buzzer as a nuisance alarm rather than the last warning before emergency spring-brake application.
What to do instead
Learn the pressure events in order: governor cut-out near 130 psi, cut-in near 100 psi, warning buzzer and light by about 60 psi, spring brakes applying in the 20–45 psi range. On the test, any question describing the buzzer sounding has one safe answer: stop and find the leak or fault before moving.
Answering pre-trip inspection questions with a general 'check it looks fine' rather than naming the specific defect criterion, such as brake slack adjuster travel beyond the allowed limit, cracked or glazed linings, or a pushrod stroke past its adjustment limit.
Candidates study the inspection as a walk-around ritual and skip the pass/fail thresholds, so they cannot pick the technically correct answer when a question asks what makes a component out of service.
What to do instead
Build a defect list with measurable limits for each item you must inspect: slack adjuster travel, brake lining thickness, tire tread depth and damage, belt condition, fluid leaks, and secure mounting of battery and exhaust. Practice stating each as 'reject if…' so the answer is a criterion, not an impression.
Stopping distance questions answered with reaction distance alone, or by adding a fixed number of feet, instead of total stopping distance = perception distance + reaction distance + brake lag distance + effective braking distance.
Candidates collapse the four components into 'reaction plus braking' and forget brake lag, which matters far more on an air-brake vehicle than on a car, so they underestimate total stopping distance at highway speed.
What to do instead
Memorize the four-part formula and be able to say what changes each part: perception and reaction grow with driver alertness, brake lag grows with air system design and slack adjustment, braking distance grows with speed squared and with weight. Work a few numeric examples at 30, 50, and 60 mph until the components are automatic.
Choosing a following distance of one second per ten feet of vehicle length at all speeds, instead of adding an extra second when speed exceeds about 40 mph.
Candidates memorize the base rule and drop the speed modifier, so they answer with the correct-looking number that is actually one second short at highway speed.
What to do instead
State the rule as a two-part formula: one second per ten feet of vehicle length, plus one additional second if traveling over 40 mph. For a 60-foot vehicle at 55 mph that is six plus one, seven seconds. Apply the same care to the four-second minimum for following a vehicle that blocks your view.
Downshifting one gear at a time while descending a long grade and relying on the service brakes to hold speed, rather than selecting a gear low enough before the descent and using engine braking with only intermittent brake applications.
Candidates treat downhill driving like flat-ground driving and do not connect brake fade and overheating to continuous service-brake use, so they pick the answer that feels natural rather than the one that preserves braking capacity.
What to do instead
Learn the rule: choose your descent gear before the grade starts, at a speed below the posted limit, and do not shift up while descending. Use the brakes firmly enough to feel a real slowdown, then release, rather than riding them lightly. Know the signs of fade and the escape-route response if brakes fail.
Answering hazard-perception questions by identifying only the hazard directly ahead, missing the stale green light, the vehicle waiting to pull out, the pedestrian near the crosswalk, or the construction zone taper that requires a plan before reaching it.
Candidates read hazard questions as recognition tests rather than scanning-and-planning tests, so they pick the obvious obstacle and ignore the cues that require an early speed or lane decision.
What to do instead
Practice the scan pattern explicitly: look far ahead, check mirrors and blind spots on a cycle, and for each hazard ask what could happen and what you will do if it does. On the test, prefer the answer that describes anticipating and planning early over the one that describes reacting late.
Signaling only at the moment of the turn or lane change, or assuming a signal gives the right of way, instead of signaling early enough to warn others and then checking mirrors and blind spots before moving.
Candidates confuse communication with permission and skip the confirm-the-space step, so they choose answers where the driver signals and moves without verifying the lane is clear.
What to do instead
Treat signaling as one step in a sequence: signal early, check mirrors, check the blind spot, then move only when the space is confirmed. Also know when signals must be used - turns, lane changes, pulling away from or into a curb, and slowing suddenly - and that a signal never grants right of way.
Describing a skid recovery as braking hard and steering away from the skid, instead of releasing the brakes, steering in the direction you want the vehicle to go, and then correcting once traction returns.
Candidates carry over instinctive car-driving reactions and do not separate the types of skid, so they pick the answer that feels like regaining control but actually worsens it.
What to do instead
Learn the recovery per skid type: for a drive-wheel or rear-wheel skid, release the accelerator or brake, steer the way you want to go, and avoid overcorrecting. For a front-wheel skid, ease off the accelerator and let the wheels regain grip before steering. Know that locked wheels from hard braking are a common cause and that releasing the brake is the first move.
Loading and securing questions answered by 'tie it down well' rather than with the actual requirements: aggregate working load limit of tiedowns at least half the cargo weight, one tiedown per ten feet of cargo length, and front-end structure or header board to protect the cab.
Candidates skim the cargo securement section because it feels like common sense, so they miss the numeric rules and the specific devices the test asks about.
What to do instead
Memorize the numbers and the reasons behind them: tiedown count based on cargo length, aggregate WLL at least half the cargo weight, cargo placed against the front structure, and covers required for loose material that could blow out. Be able to name the tiedown types and what each is suited to.
Treating the vehicle inspection as a formality performed once, instead of answering questions about en-route checks - after the first 50 miles and every 150 miles or three hours thereafter - and about inspecting cargo and securing devices during those stops.
Candidates prepare for the pre-trip walk-around and do not study the inspection-during-a-trip rules, so they miss questions about when to re-check tires, brakes, cargo, and lights.
What to do instead
Learn the en-route schedule and what triggers an unscheduled check: the first 50 miles, then every 150 miles or three hours, plus after any incident or when something feels wrong. Remember that cargo and tiedowns are part of every en-route check, not just the pre-trip.