CSLB General Building (B) — All Questions

Before backing a tractor under a trailer, where should the trailer be positioned relative to the fifth wheel?

• a.Slightly higher than the fifth wheel so it can slide up as you back
• b.Low enough that the trailer is raised slightly by the tractor as you back under it✓
• c.At the exact same height so no lifting occurs
• d.Below the frame rails so the kingpin drops in freely

The trailer should be low enough that it is raised slightly when the tractor backs under it. This ensures the fifth wheel makes solid contact and the kingpin seats properly. If the trailer is too low the tractor may hit and damage the nose; too high and it can miss the fifth wheel.

What is the correct order for positioning the tractor before coupling to a trailer?

• a.Line the tractor directly in front of the trailer, never backing under it at an angle✓
• b.Approach from the side to save time
• c.Back in from a 45-degree angle for better vision
• d.Position the tractor with the fifth wheel already tilted forward

You should line the tractor up directly in front of the trailer and never back under at an angle. Backing under at an angle can push the trailer sideways and break the landing gear. Approaching straight also helps the kingpin center in the fifth wheel jaws.

Before backing under a trailer, the fifth wheel should be tilted how?

• a.Tilted down toward the rear of the tractor
• b.Kept perfectly level
• c.Tilted down toward the rear so the kingpin can rise into the jaws✓
• d.Locked flat with jaws already closed

The fifth wheel should be tilted down toward the rear of the tractor so the kingpin can slide up the ramp and into the locking jaws. The jaws must be open before backing under. A properly tilted fifth wheel allows smooth coupling and correct kingpin seating.

When connecting the glad hands, what must you check to avoid a dangerous coupling mistake?

• a.That both hoses are the same color
• b.That the hoses are as short as possible
• c.That the tractor engine is running
• d.That the emergency (red) and service (blue) lines are connected to the correct couplers, not crossed✓

You must make sure the emergency and service air lines are connected to the correct glad hands and not crossed. Crossing the lines can leave the trailer with no emergency brake protection. Many rigs color-code red for emergency and blue for service to prevent mistakes.

After the kingpin has locked into the fifth wheel, how should you test that the coupling is secure?

• a.Put the tractor in low gear and gently pull forward against the locked trailer brakes (tug test)✓
• b.Rev the engine while in neutral
• c.Bounce the cab up and down
• d.Release all air and roll forward

You should perform a tug test by putting the tractor in low gear and gently pulling forward while the trailer brakes are locked. If the coupling is secure, the trailer will not separate. This confirms the kingpin is fully engaged before you crawl under to inspect.

After the tug test, why should you go under the trailer and look into the back of the fifth wheel?

• a.To check the color of the kingpin
• b.To confirm the fifth wheel jaws have closed around the shank of the kingpin✓
• c.To measure the height of the landing gear
• d.To grease the fifth wheel plate

You should go under the trailer with a flashlight and look at the back of the fifth wheel to confirm the locking jaws have closed completely around the shank, not the head, of the kingpin. This visual check catches a false coupling that the tug test alone might miss. A gap means the coupling is not safe.

When should the locking jaws be closed around the kingpin?

• a.Around the top head of the kingpin
• b.Loosely, so the trailer can pivot freely
• c.Around the shank of the kingpin, with no gap between the upper and lower fifth wheel plates✓
• d.Only after the landing gear is fully lowered

The locking jaws must close around the shank of the kingpin, and there should be no space between the upper and lower fifth wheel plates. If the jaws close on the head of the kingpin, the coupling can come apart. A gap between the plates indicates a bad coupling that must be corrected before driving.

After the trailer is securely coupled and supported by the tractor, what should you do with the landing gear?

• a.Leave it partway down for extra support
• b.Raise it only halfway
• c.Leave it fully down until you reach the destination
• d.Raise it fully and secure the crank handle✓

Once the trailer weight rests on the tractor, raise the landing gear all the way up and secure the crank handle in its holder. Landing gear left partway down can catch on railroad tracks or uneven surfaces. A loose crank handle can strike someone or damage equipment.

Before supplying air to the trailer, why should you check the trailer brakes are set?

• a.To keep the trailer from moving when the tractor backs under it or when air is applied✓
• b.To warm up the brake shoes
• c.To test the ABS light
• d.To release the parking brake automatically

You should ensure the trailer brakes are locked, either with wheel chocks or by having air already in the system, so the trailer cannot move while coupling. A trailer that rolls during coupling can cause serious injury or damage. Chock the wheels if you are not sure the spring brakes will hold.

When you push the trailer air supply valve in (supply air to trailer), what should happen?

• a.The trailer parking brakes stay locked
• b.Air flows to the trailer and the trailer spring brakes release✓
• c.The tractor engine shuts off
• d.The fifth wheel unlocks

Pushing in the trailer air supply valve sends air to the trailer, which releases the trailer spring (parking) brakes. You should always charge the trailer air and then test the brakes before moving. This step is done after confirming the air lines are connected correctly.

During uncoupling, when should you lower the landing gear?

• a.After pulling the tractor completely out
• b.Only if the trailer is empty
• c.Before releasing the fifth wheel locking jaws, until it makes firm contact with the ground✓
• d.At the same time you pull the fifth wheel release handle

You should lower the landing gear until it makes firm contact with the ground before unlocking the fifth wheel. If the trailer is loaded, turn the crank a few extra times to lift some weight off the tractor. This prevents the trailer from dropping suddenly when the tractor pulls out.

What should you do with the air lines and electrical cord before pulling the tractor away from the trailer during uncoupling?

• a.Leave them connected and let them stretch off
• b.Cut them if they are stuck
• c.Wrap them around the kingpin
• d.Disconnect them and hang or store them so they will not be crushed or dragged✓

Before pulling the tractor clear, disconnect the air lines and electrical cord and secure them so they are not damaged. Hang the glad hands on dummy couplers or dead-end them to keep dirt out. Leaving lines connected can tear them apart when the tractor drives away.

When uncoupling, what does pulling the fifth wheel release handle to the open position do?

• a.Unlocks the fifth wheel locking jaws so the kingpin can slide out✓
• b.Raises the landing gear
• c.Supplies air to the trailer
• d.Locks the trailer brakes

Pulling the release handle to the open position unlocks the fifth wheel jaws so the trailer kingpin can separate as the tractor pulls forward. You should only do this after the landing gear supports the trailer and the trailer brakes are set. Chock the wheels if the trailer has no spring brakes.

After unlocking the fifth wheel jaws during uncoupling, how should you move the tractor?

• a.Pull forward quickly to clear the area
• b.Ease the tractor forward until the fifth wheel comes out from under the trailer, then stop✓
• c.Back up sharply to free the kingpin
• d.Turn hard while pulling out

You should ease the tractor forward slowly until the fifth wheel comes out from under the trailer apron, then stop with the tractor frame still under the trailer. This keeps the trailer supported while you disconnect lines. Pulling out too far or too fast before the trailer is fully supported can drop the trailer.

Why is it important that the kingpin be properly locked, not just resting on the closed fifth wheel jaws?

• a.To reduce fuel use
• b.To keep the fifth wheel greased
• c.Because a kingpin resting on top of the closed jaws (a false coupling) can slip out and separate the trailer✓
• d.Because it makes turning easier

A false coupling occurs when the fifth wheel jaws close but the kingpin is sitting on top of them rather than locked around the shank. This looks connected but can separate under load or over bumps, dropping the trailer. That is why the tug test and the visual under-trailer check are both required.

When raising the landing gear after coupling, what should you be aware of regarding the crank handle?

• a.It should be left extended for balance
• b.It cannot be secured
• c.It should spin freely while driving
• d.It must be secured in its holder so it does not swing out or get caught✓

After fully raising the landing gear, the crank handle must be secured in its holder. An unsecured handle can swing out and strike people, other vehicles, or catch on obstacles. Always confirm the gear is fully up and the handle is stowed before moving.

Why should you use two low-pressure gears when starting to raise loaded landing gear rather than high gear?

• a.Low gear makes cranking easier and reduces the risk of injury when lifting heavy loads✓
• b.High gear is faster and always preferred
• c.Low gear damages the crank
• d.Landing gear has only one gear

Many landing gear cranks have a low and a high gear. Use the low gear to start raising a heavy load because it takes less effort, then switch to high gear once the weight is off. Trying to crank a heavy load in high gear can strain the mechanism and cause injury.

What should you check about the fifth wheel plate before backing under a trailer?

• a.That it is painted the correct color
• b.That it is properly greased to prevent steering problems and reduce friction✓
• c.That it is completely dry
• d.That the jaws are already closed

The fifth wheel plate should be properly lubricated with grease to reduce friction between the trailer and tractor. A dry fifth wheel can cause steering problems and hard, jerky turning. You should also confirm the jaws are open and the fifth wheel is tilted down before backing under.

Before coupling, why should you inspect the area around and under the trailer?

• a.To count the tires
• b.To look for a place to park the tractor
• c.To check for people, obstacles, or objects and confirm the trailer wheels are chocked or brakes set✓
• d.To adjust the mirrors

You should walk around and check under the trailer for people, pets, or obstacles before backing under it. Confirm the trailer wheels are chocked or the trailer brakes are set so it cannot move. This inspection prevents injury and equipment damage during coupling.

Which of the following is the correct sequence when coupling a tractor and trailer?

• a.Raise landing gear, then back under, then connect air lines
• b.Connect air lines, then tug test, then position tractor
• c.Back under, raise landing gear, then set trailer height
• d.Inspect and prepare, back under and couple, connect air lines and supply air, test coupling, raise landing gear✓

The proper sequence is to inspect and prepare the equipment, back under and couple, connect and supply air lines, test the coupling with a tug test and visual check, then raise the landing gear. Following the correct order prevents a false coupling and dropped trailer. Skipping steps like the air connection or tug test is dangerous.

What is the purpose of the safety catch on many fifth wheel release levers?

• a.It must be released before the fifth wheel handle can be pulled to unlock, preventing accidental uncoupling✓
• b.It greases the fifth wheel automatically
• c.It holds the trailer brakes on
• d.It raises the landing gear

Many fifth wheels have a safety catch over the release lever that must be moved before the handle can be pulled. This prevents the fifth wheel from unlocking accidentally while driving. You release the catch only when you intend to uncouple.

If the trailer is too low when you back under it, what is the likely result?

• a.The kingpin locks perfectly
• b.The tractor may strike and damage the nose of the trailer instead of coupling✓
• c.The landing gear rises automatically
• d.The glad hands connect themselves

If the trailer is set too low, the tractor frame or fifth wheel can hit and damage the front of the trailer rather than sliding underneath. If it is too high, the tractor may pass under without the kingpin engaging the fifth wheel. The trailer should be just low enough to be lifted slightly during coupling.

Why must you supply air to the trailer and check for air leaks before moving after coupling?

• a.To cool the engine
• b.To inflate the tires
• c.To confirm the trailer brakes work and the air system holds pressure before driving✓
• d.To lower the landing gear

After connecting the air lines you must supply air to the trailer and check that the system holds pressure and the trailer brakes operate. Listening for leaks and watching the gauge confirms the braking system is sealed. Driving with a leaking or unconnected trailer air line can leave you without trailer brakes.

When should you chock the trailer wheels during coupling or uncoupling?

• a.Never, the fifth wheel holds the trailer
• b.Only on flat ground
• c.Only when the tractor is attached
• d.When you are not sure the trailer spring brakes will hold it, such as an empty or brakeless trailer✓

You should chock the trailer wheels whenever you are unsure the trailer will stay in place, such as a trailer without spring brakes or one parked on a slope. Chocks keep the trailer from rolling during coupling or uncoupling. This protects you from a runaway trailer while you work between the units.