NY CDL Combination cheat sheet

Pre-trip order for a combination: coupling system first (fifth wheel, locking jaws, safety latch, kingpin, air/electric lines), then landing gear, mud flaps, lights, tires, wheels and rims, brakes, suspension, and rear of trailer.

Fifth wheel inspection: jaws must be fully closed around the kingpin, the release lever must be in the locked position, and the safety latch must be over or through the handle.

Tug test: after coupling, pull forward slowly with the trailer brakes set (or tractor brakes released and trailer brakes applied) to confirm the kingpin is locked; the tractor should not move.

Coupling sequence: inspect the fifth wheel and kingpin, back under slowly, hear and feel the click, tug test, visually check the jaws, raise landing gear, connect air lines, connect electrical cord, then release trailer spring brakes.

Air line order: connect the emergency (supply) line before the service line; on some systems the service line will not charge until the emergency line is connected.

Uncoupling sequence: park on firm level ground, set the parking brake, chock wheels if needed, lower landing gear, disconnect electrical cord and air lines, release the fifth wheel latch, then pull forward slowly.

Landing gear must contact the ground and take the trailer weight before the fifth wheel is released; a trailer dropped without gear contact can tip or crush the tractor frame.

After coupling, check that the air lines and electrical cord have enough slack for turns and that they are not resting on the catwalk or dragging.

Off-tracking: the rear wheels of a combination follow a shorter path than the front wheels; the longer the wheelbase, the greater the off-tracking.

Rule of thumb: a 50-foot tractor-trailer 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 rear of the trailer swings outside the front path during a turn; the wider the turn, the more the trailer tail swings out.

Right turns: swing wide to the left before turning right, but do not swing so wide that you cross the centerline or force traffic into the curb lane.

Left turns: keep the trailer close to the inside of the turn; if you turn too sharply, the trailer wheels will cut the corner and can hit curbs or pedestrians.

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.

Lane tracking: use the mirrors to confirm the trailer is centered in the lane; the trailer will not track exactly behind the tractor.

Backing: back toward the driver's side (left) whenever possible; use a spotter or get out and check the area before backing.

Total stopping distance = perception distance + reaction distance + brake lag distance + effective braking distance.

Brake lag on an air brake system is about 0.4 second; at 55 mph that is roughly 32 feet traveled before the brakes begin to act.

Push the brake pedal down and hold it; fanning or pumping the pedal wastes air pressure and can leave you without enough air to stop.

Brake adjustment: with the system at normal pressure, a fully applied brake should not move more than about 1 inch of pushrod travel on a standard chamber.

Leak test: with the engine off and the system charged, apply and hold the brakes; pressure should not drop more than 3 psi in one 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; the spring brakes will begin to apply around 20 to 45 psi.

Trailer brakes must be connected and working; if the trailer brake line is disconnected, the trailer emergency brakes will lock and the combination can jackknife.

Use a lower gear before a long downgrade; do not rely on the brakes alone to control speed, and never coast in neutral.

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.

Speed in curves: enter a curve below the posted speed, and slow further when the trailer is loaded or the center of gravity is high.

Centrifugal force increases with the square of speed: doubling speed quadruples the force pushing the vehicle outward in a curve.

High center of gravity: cargo loaded high or a partially filled tank raises the rollover risk; keep the load low and centered.

Following distance: 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.

Downhill speed: 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.

Weather and road: reduce speed on wet, icy, or gravel surfaces; the trailer can begin to slide before the tractor shows any loss of traction.

Jackknife types: a drive-axle jackknife occurs when the drive wheels lose traction and the tractor swings; a trailer jackknife occurs when the trailer wheels lose traction and the trailer swings.

Drive-axle jackknife recovery: release the brakes and steer in the direction the tractor is sliding; do not apply more braking until the wheels regain traction.

Trailer jackknife recovery: release the brakes and steer to keep the tractor and trailer aligned; a locked trailer brake can cause the trailer to swing.

Skid recovery rule: stop braking, look and steer where you want to go, and do not overcorrect; the vehicle will straighten as traction returns.

Front-wheel skid: release the brakes and steer in the direction of the skid; the front wheels must roll to regain steering control.

Emergency stop: apply the brakes firmly and hold, keep the steering straight, and do not swerve if a collision is unavoidable; swerving can cause a rollover.

Tire blowout: hold the steering wheel firmly, keep the vehicle straight, ease off the accelerator, and brake gently once control is regained.

Runaway ramp: if brakes fail on a downgrade, use the runaway truck ramp; aim for the center of the ramp and keep the vehicle straight.

Pre-trip order for a combination: coupling system first (fifth wheel, locking jaws, safety latch, kingpin, air/electric lines), then landing gear, mud flaps, lights, tires, wheels and rims, brakes, suspension, and rear of trailer.

Fifth wheel inspection: jaws must be fully closed around the kingpin, the release lever must be in the locked position, and the safety latch must be over or through the handle.

Tug test: after coupling, pull forward slowly with the trailer brakes set (or tractor brakes released and trailer brakes applied) to confirm the kingpin is locked; the tractor should not move.

Coupling sequence: inspect the fifth wheel and kingpin, back under slowly, hear and feel the click, tug test, visually check the jaws, raise landing gear, connect air lines, connect electrical cord, then release trailer spring brakes.

Air line order: connect the emergency (supply) line before the service line; on some systems the service line will not charge until the emergency line is connected.

Uncoupling sequence: park on firm level ground, set the parking brake, chock wheels if needed, lower landing gear, disconnect electrical cord and air lines, release the fifth wheel latch, then pull forward slowly.

Landing gear must contact the ground and take the trailer weight before the fifth wheel is released; a trailer dropped without gear contact can tip or crush the tractor frame.

After coupling, check that the air lines and electrical cord have enough slack for turns and that they are not resting on the catwalk or dragging.

Off-tracking: the rear wheels of a combination follow a shorter path than the front wheels; the longer the wheelbase, the greater the off-tracking.

Rule of thumb: a 50-foot tractor-trailer 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 rear of the trailer swings outside the front path during a turn; the wider the turn, the more the trailer tail swings out.

Right turns: swing wide to the left before turning right, but do not swing so wide that you cross the centerline or force traffic into the curb lane.

Left turns: keep the trailer close to the inside of the turn; if you turn too sharply, the trailer wheels will cut the corner and can hit curbs or pedestrians.

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.

Lane tracking: use the mirrors to confirm the trailer is centered in the lane; the trailer will not track exactly behind the tractor.

Backing: back toward the driver's side (left) whenever possible; use a spotter or get out and check the area before backing.

Total stopping distance = perception distance + reaction distance + brake lag distance + effective braking distance.

Brake lag on an air brake system is about 0.4 second; at 55 mph that is roughly 32 feet traveled before the brakes begin to act.

Push the brake pedal down and hold it; fanning or pumping the pedal wastes air pressure and can leave you without enough air to stop.

Brake adjustment: with the system at normal pressure, a fully applied brake should not move more than about 1 inch of pushrod travel on a standard chamber.

Leak test: with the engine off and the system charged, apply and hold the brakes; pressure should not drop more than 3 psi in one 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; the spring brakes will begin to apply around 20 to 45 psi.

Trailer brakes must be connected and working; if the trailer brake line is disconnected, the trailer emergency brakes will lock and the combination can jackknife.

Use a lower gear before a long downgrade; do not rely on the brakes alone to control speed, and never coast in neutral.

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.

Speed in curves: enter a curve below the posted speed, and slow further when the trailer is loaded or the center of gravity is high.

Centrifugal force increases with the square of speed: doubling speed quadruples the force pushing the vehicle outward in a curve.

High center of gravity: cargo loaded high or a partially filled tank raises the rollover risk; keep the load low and centered.

Following distance: 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.

Downhill speed: 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.

Weather and road: reduce speed on wet, icy, or gravel surfaces; the trailer can begin to slide before the tractor shows any loss of traction.

Jackknife types: a drive-axle jackknife occurs when the drive wheels lose traction and the tractor swings; a trailer jackknife occurs when the trailer wheels lose traction and the trailer swings.

Drive-axle jackknife recovery: release the brakes and steer in the direction the tractor is sliding; do not apply more braking until the wheels regain traction.

Trailer jackknife recovery: release the brakes and steer to keep the tractor and trailer aligned; a locked trailer brake can cause the trailer to swing.

Skid recovery rule: stop braking, look and steer where you want to go, and do not overcorrect; the vehicle will straighten as traction returns.

Front-wheel skid: release the brakes and steer in the direction of the skid; the front wheels must roll to regain steering control.

Emergency stop: apply the brakes firmly and hold, keep the steering straight, and do not swerve if a collision is unavoidable; swerving can cause a rollover.

Tire blowout: hold the steering wheel firmly, keep the vehicle straight, ease off the accelerator, and brake gently once control is regained.

Runaway ramp: if brakes fail on a downgrade, use the runaway truck ramp; aim for the center of the ramp and keep the vehicle straight.