NY CDL Combination flashcards
NY CDL Combination · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Tug test
- After coupling, pull the tractor forward slowly with the trailer brakes applied. If the kingpin is locked, the tractor will not move; if it moves, the coupling is not secure.
- Fifth wheel jaws
- The locking mechanism that grips the trailer kingpin. Jaws must be fully closed around the kingpin and the release lever locked with the safety latch engaged.
- Landing gear check
- Before releasing the fifth wheel, lower the landing gear until it contacts the ground and supports the trailer weight; otherwise the trailer can tip or damage the tractor.
- Air line connection order
- Connect the emergency (supply) line before the service line. On many systems the service line will not charge until the emergency line is connected.
- Coupling sequence
- Inspect fifth wheel and kingpin, back under slowly, hear the click, tug test, check jaws, raise landing gear, connect air lines, connect electrical cord, release trailer brakes.
- Uncoupling sequence
- Park on firm level ground, set parking brake, chock wheels, lower landing gear, disconnect electrical cord and air lines, release fifth wheel latch, pull forward slowly.
- Pre-trip combination order
- Start at the coupling system, then check landing gear, mud flaps, lights, tires, wheels, brakes, suspension, and the rear of the trailer.
- Off-tracking
- The tendency of the rear wheels of a combination to follow a shorter path than the front wheels. Longer wheelbase produces greater off-tracking.
- Off-tracking rule of thumb
- A combination off-tracks about 2 feet for each 10 feet of wheelbase beyond the first 50 feet. A 90-foot combination tracks roughly 8 feet inside the front path.
- Swept path
- The path swept by the outer rear corner of the trailer during a turn. The trailer tail swings outside the front path, so watch mirrors and clearance.
- Right turn procedure
- Swing wide to the left before turning right, but do not cross the centerline or force traffic into the curb lane. Complete the turn slowly.
- Left turn procedure
- Keep the trailer close to the inside of the turn. Turning too sharply makes the trailer wheels cut the corner and can strike curbs or pedestrians.
- Backing a combination
- Back toward the driver's side (left) whenever possible. Use a spotter or get out and check the area before backing.
- Turning radius
- A combination vehicle needs a much larger turning radius than a single unit. Plan turns from the far lane and complete them at low speed.
- Total stopping distance
- Perception distance plus reaction distance plus brake lag distance plus effective braking distance. All four components add to the distance needed to stop.
- Air brake lag
- About 0.4 second between pressing the pedal and the brakes acting. At 55 mph that is roughly 32 feet traveled before braking begins.
- Brake fade
- Loss of braking power from overheating, common on long downgrades. Use a lower gear and engine braking instead of riding the brakes.
- Leak test
- With the engine off and system charged, hold the brakes. Pressure should not drop more than 3 psi per minute for a single vehicle or 4 psi for a combination.
- Low air warning
- The warning buzzer or light must activate before pressure drops below 60 psi. Spring brakes begin to apply around 20 to 45 psi.
- Brake adjustment
- At normal pressure, a fully applied brake should not move more than about 1 inch of pushrod travel on a standard chamber.
- Fanning the brake pedal
- Pumping or fanning the pedal wastes air pressure and can leave the system without enough air to stop. Push down and hold instead.
- Rollover threshold
- A loaded combination can roll over at lateral acceleration of roughly 0.4 g or less. Posted curve speeds assume a lower center of gravity than a loaded trailer.
- Centrifugal force and speed
- Centrifugal force increases with the square of speed. Doubling speed in a curve quadruples the outward force pushing the vehicle toward rollover.
- Following distance rule
- Allow at least one second per 10 feet of vehicle length plus one second. A 60-foot combination needs about 7 seconds at highway speed.
- High center of gravity
- Cargo loaded high or a partially filled tank raises rollover risk. Keep the load low and centered to lower the center of gravity.
- Downhill speed control
- Shift to a lower gear before the grade and use engine braking. A combination gains speed faster than a single unit on a downgrade.
- Smooth control
- Avoid sudden steering, hard braking, and rapid acceleration. Abrupt inputs can upset a loaded trailer and cause a rollover.
- Drive-axle jackknife
- The drive wheels lose traction and the tractor swings. Release the brakes and steer in the direction the tractor is sliding.
- Trailer jackknife
- The trailer wheels lose traction and the trailer swings. Release the brakes and steer to keep the tractor and trailer aligned.
- Front-wheel skid recovery
- Release the brakes and steer in the direction of the skid. The front wheels must roll to regain steering control.
- Tire blowout procedure
- Hold the steering wheel firmly, keep the vehicle straight, ease off the accelerator, and brake gently once control is regained.
- Runaway truck ramp
- If brakes fail on a downgrade, use the runaway ramp. Aim for the center of the ramp and keep the vehicle straight to avoid a rollover.