Alabama CDL Combination Vehicles Practice Test 2019
THERE ARE TWO THINGS THAT A DRIVER CAN DO TO PREVENT A ROLLOVER. THEY ARE "GO SLOW AROUND CORNERS" AND _____.
The following two things will help you prevent rollover, 1) keep the cargo as close to the ground as possible, and 2) drive slowly around turns. Keeping cargo low is even more important in combination vehicles than in straight trucks.
WHY SHOULD YOU NOT USE THE TRAILER HAND VALVE WHILE DRIVING?
The trailer hand valve should be used only to test the trailer brakes. Do not use it in driving because of the danger of making the trailer skid. The foot brake sends air to all of the brakes on the vehicle (including the trailer(s). There is much less danger of causing a skid or jackknife when using just the foot brake.
WHEN YOU BACK A TRAILER, YOU SHOULD POSITION YOUR VEHICLE SO YOU CAN BACK IN A CURVED PATH TO THE DRIVER’S SIDE. TRUE OR FALSE?
When you have to back, start in the proper position. Look at your path and use mirrors on both sides and back slowly. Back and turn toward the driver's side whenever possible and use a helper.
WHAT MIGHT HAPPEN IF THE TRAILER IS TOO HIGH WHEN YOU TRY TO COUPLE?
The trailer should be low enough that it is raised slightly by the tractor when the tractor is backed under it. Raise or lower the trailer as needed. If the trailer is too low, the tractor may strike and damage the trailer nose. If the trailer is too high, it may not couple correctly.
YOU ARE DRIVING A SEMI AND THE TRAILER BREAKS AWAY, PULLING APART THE AIR LINES. YOU EXPECT THE TRAILER BRAKES TO COME ON AND ____ .
When the trailer breaks away and severs the emergency air line, emergency brakes on the trailer engage. At the same time, the tractor bakes will remain operational.
WHICH SHUT-OFF VALVES SHOULD BE OPEN AND WHICH CLOSED?
To test that air reaches all the way to the back of the last trailer, you can open shut-off valves at the rear of the last trailer, on both the service and the emergency lines. You should hear the air escaping. Close the valves. If you do not hear the air escaping from both lines, check to see that the shut-off valves on the previous trailer/tractor are in the open position.
THE AIR LEAKAGE RATE FOR A COMBINATION VEHICLE (ENGINE OFF, BRAKES OFF) SHOULD BE NO MORE THAN ____ PSI PER MINUTE.
The air loss rate should be less than 2 psi in one minute for single vehicles and less than 3 psi in one minute for combination vehicles when no brakes are engaged.
THE FEWER AXLES ON A UNIT, THE MORE STABLE IT IS?
Our of two units of comparable weight and length, a unit with fewer axles will have more rearward amplification and is more likely to roll over in a turn.
AIR LINES ON A COMBINATION VEHICLE ARE OFTEN COLORED TO KEEP THEM FROM GETTING MIXED UP. THE EMERGENCY LINE IS ____; THE SERVICE LINE IS ____.
The emergency line (also called the supply line) line is always coded with red color, while the service air line is labeled with blue color.
WHAT IS OFF-TRACKING?
Off-tracking causes the path followed by a tractor to be wider than the rig itself. Longer vehicles will off-track more. The rear wheels of the powered unit (truck or tractor) will off-track some, and the rear wheels of the trailer will off-track even more.
COMBINATION VEHICLES ARE USUALLY HEAVIER, LONGER, AND REQUIRE MORE DRIVING SKILL THAN SINGLE COMMERCIAL VEHICLES.
Combination vehicles are usually heavier, longer, and require more driving skill than single commercial vehicles. This means that drivers of combination vehicles need more knowledge and skill than drivers of single vehicles.
HOW CAN YOU TEST THE TRAILER EMERGENCY BRAKES?
Charge the trailer air brake system and check that the trailer rolls freely. Then stop and pull out the trailer air supply control (also called tractor protection valve control or trailer emergency valve), or place it in the “emergency” position. Pull gently on the trailer with the tractor to check that the trailer emergency brakes are on.
THE SAFETY LATCH FOR THE FIFTH WHEEL LOCKING LEVER MUST BE ____ FOR A COUPLING TO BE COMPLETE
While inspecting coupling, check that the fifth wheel locking lever is in the lock position and that the safety latch is in position over locking lever (on some fifth wheels the catch must be put in place by hand).
WHAT TYPE OF TRAILERS CAN GET STUCK ON RAILROAD-HIGHWAY CROSSINGS?
Low-slung units (lowboy, car carrier, moving van, possum-belly livestock trailer) and single-axle tractor pulling a long trailer with its landing gear set to accommodate a tandem-axle tractor stand a higher chance of getting stuck on a railroad-highway crossing.
TRAILER MADE BEFORE 1975, EQUIPPED WITH AIR BRAKES:
Newer trailers have spring brakes just like trucks and truck tractors; however, converter dollies and trailers built before 1975 are not required to have spring brakes. Those that do not have spring brakes have emergency brakes, which work from the air stored in the trailer air tank.
WHAT PART OF THE KINGPIN SHOULD THE LOCKING JAWS CLOSE AROUND?
The fifth wheel jaws must close around the shank of the kingpin. If the coupling isn't right, don't drive the coupled unit, the trailer may come loose easily.
THERE ARE TWO THINGS THAT A DRIVER CAN DO TO PREVENT A ROLLOVER. THEY ARE "GO SLOW AROUND CORNERS" AND _____.
The following two things will help you prevent rollover, 1) keep the cargo as close to the ground as possible, and 2) drive slowly around turns. Keeping cargo low is even more important in combination vehicles than in straight trucks.
YOU ARE DRIVING A SEMI AND THE TRAILER BREAKS AWAY, PULLING APART THE AIR LINES. YOU EXPECT THE TRAILER BRAKES TO COME ON AND ____ .
When the trailer breaks away and severs the emergency air line, emergency brakes on the trailer engage. At the same time, the tractor bakes will remain operational.
COMBINATION VEHICLES ARE USUALLY HEAVIER, LONGER, AND REQUIRE MORE DRIVING SKILL THAN SINGLE COMMERCIAL VEHICLES.
Combination vehicles are usually heavier, longer, and require more driving skill than single commercial vehicles. This means that drivers of combination vehicles need more knowledge and skill than drivers of single vehicles.
WHAT IS OFF-TRACKING?
Off-tracking causes the path followed by a tractor to be wider than the rig itself. Longer vehicles will off-track more. The rear wheels of the powered unit (truck or tractor) will off-track some, and the rear wheels of the trailer will off-track even more.