Michigan CDL Combination flashcards
Michigan 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.
- Brake lag distance
- The distance traveled while air pressure moves through the lines before brakes apply; about 32 feet at 55 mph, roughly 1.1 feet per mph.
- Perception distance
- The distance traveled from seeing a hazard to the brain recognizing it; about 60 feet at 55 mph, before any reaction begins.
- Reaction distance
- The distance traveled from recognizing a hazard to physically applying the brake; about 61 feet at 55 mph.
- Stab braking
- A technique for hot, fading brakes: push the pedal hard, release fully, and repeat; do not fan or pump lightly.
- Tire tread minimum
- Front steer tires need at least 4/32 inch tread depth; all other tires need at least 2/32 inch; no cuts or exposed cord.
- Air leak test
- With engine off and full pressure, loss must not exceed 3 psi per minute for a single vehicle or 4 psi for a combination.
- Applied leak test
- With brakes fully applied and held one minute, air loss must not exceed 4 psi; low-pressure warning must sound by 60 psi.
- Slack adjuster check
- With brakes released, push the slack adjuster by hand; movement at the chamber push rod should be about 1 inch or less.
- Fifth wheel inspection
- Jaws fully closed around the kingpin, no gap between upper and lower plates, release handle locked, and safety latch engaged.
- Pull test
- After locking the fifth wheel jaws, apply trailer spring brakes and pull forward gently to confirm the kingpin is captured.
- Coupling sequence
- Inspect fifth wheel, back under trailer, secure tractor, connect lines, lock jaws, raise landing gear, then pull test.
- Uncoupling sequence
- Park, chock wheels, lower landing gear, disconnect lines, release jaws, then pull forward slowly.
- Landing gear support
- Lower landing gear until it firmly contacts the ground and supports the trailer before releasing the fifth wheel.
- Tractor protection valve
- A valve that closes automatically during a trailer breakaway, sealing the tractor's air supply so it keeps pressure.
- Spring brakes
- Emergency and parking brakes that apply automatically when air pressure drops to roughly 20-45 psi.
- Low air warning
- A buzzer or light that must activate before pressure drops below 60 psi, signaling the driver to stop safely.
- Supply vs service line
- The supply (emergency) line charges the trailer air tanks; the service (control) line applies the trailer brakes.
- Trailer hand valve
- The trolley valve used only to test trailer brakes; never use it to park, because it can leak and release brakes.
- Off-tracking
- The tendency of rear wheels to follow a shorter path than front wheels; a long trailer can off-track several feet in a turn.
- Swing-out
- The outward swing of the tractor's rear and the trailer's front opposite the turn direction; check mirrors before turning.
- Backing steering rule
- Steer the top of the steering wheel in the direction you want the trailer to go; back toward the driver's side when possible.
- GOAL
- Get Out And Look: stop and inspect the area behind the trailer when visibility is poor or space is tight.
- Right turn technique
- Swing wide to the left without entering oncoming traffic; a large combination may need both lanes to clear the corner.
- Rear-wheel skid recovery
- Stop braking, steer in the direction you want to go, and avoid overcorrecting to regain traction.
- Front-wheel skid
- The vehicle will not respond to steering; ease off the accelerator and brake gently to regain traction.
- Jackknife recovery
- Release the brakes so trailer wheels roll and regain traction, then steer to straighten the combination.
- ABS use
- Anti-lock braking prevents wheel lockup; do not pump the brakes on ABS-equipped vehicles, just hold firm pressure.
- Tiedown load limit
- The aggregate working load limit of tiedowns must be at least 50 percent of the cargo weight being secured.
- Minimum tiedowns
- One tiedown for cargo up to 1,100 lbs, two for 1,100-2,200 lbs, and three for cargo over 2,200 lbs.
- Axle weight limits
- Steer axle about 12,000 lbs, drive tandems about 34,000 lbs, trailer tandems about 34,000 lbs, gross up to 80,000 lbs.
- Following distance rule
- At least one second per 10 feet of vehicle length under 40 mph; add one second when speeds exceed 40 mph.
- Space cushion
- Keep space to the front, sides, and rear; avoid driving in another vehicle's blind spot for extended periods.