Combination Vehicle Operations Flashcards
7 cards from real CLP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Combination Vehicle Operations flashcards as text
What is the off-tracking difference in a long combination vehicle compared to a single unit truck?
Answer: The rear wheels follow a significantly shorter path (inside) than the front wheels when turning
Off-tracking causes the rear wheels to cut corners more severely than the front wheels, requiring drivers to allow extra space on the inside of turns.
Under FMCSA regulations, the maximum overall length for a twin-trailer (doubles) combination on most interstate highways is:
Answer: No overall length limit on the combination, but each trailer is limited to 28.5 feet
Federal law grandfathers twin 28.5-foot trailers on the National Network with no set overall combination length limit, though trailer length is capped at 28.5 feet each.
When should you drain the air tanks on a combination vehicle?
Answer: At the end of each day or before a major trip to remove moisture that can freeze and cause brake failure
Moisture accumulates daily and can freeze in cold weather, blocking air lines and causing brake failure, so daily draining is required.
What is the safest way to prevent a tractor jackknife when braking hard on a slippery road without ABS?
Answer: Brake firmly but release and reapply before the drive wheels lock up
Stab braking or threshold braking keeps drive wheels from locking, which is what causes the tractor to swing out in a jackknife.
What is the purpose of the pintle hook on a full trailer or converter dolly?
Answer: It provides the mechanical connection point that the drawbar eye of the following unit latches onto
The pintle hook is a hook-type coupler that the drawbar eye of the trailer or dolly latches into, forming the towing connection.
Why is it dangerous to disconnect the air lines before uncoupling the fifth wheel?
Answer: The trailer spring brakes may not apply, allowing the unsupported trailer to roll freely
If air lines are disconnected first, the emergency line loses pressure and should apply spring brakes, but improper sequencing can leave the trailer free to roll.
What is the FIRST step when performing a pre-trip inspection on a combination vehicle's coupling system?
Answer: Check that the fifth wheel is properly mounted and that the mounting bolts are secure
The foundation of safe coupling is a properly mounted fifth wheel; loose mounting bolts can allow it to shift and cause separation.