CDL combination vehicles practice test 5

B: You might push the trailer sideways and break the landing gear. Put the tractor directly in front of the trailer. Backing under at an angle might push the trailer sideways and break the landing gear. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

A: Until the fifth wheel just touches the trailer, without hitting it. Back slowly until the fifth wheel just touches the trailer, without hitting the trailer. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

A: Low enough that the tractor raises it slightly when backing under. Set the trailer just low enough that the tractor lifts it a little as it backs under. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

C: Too low: the tractor may strike and damage the trailer nose. Too high: it may not couple correctly. A trailer set too low can be hit by the tractor, damaging its nose. One set too high may not couple properly. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

D: Emergency line first, then service line. The manual's Step 7 lists connecting the tractor emergency line to the trailer emergency glad hand, then the service line to the service glad hand. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

C: So you can hear the trailer brakes being applied and released. Shut the engine off so you can hear the brakes. Apply and release the trailer brakes and listen for them to move and for air to escape when released. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

B: Pull out the 'air supply' knob, or move the tractor protection valve control from 'normal' to 'emergency'. In Step 9, set the trailer brakes by pulling the air supply knob out, or by moving the tractor protection valve control from 'normal' to 'emergency'. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

B: The lowest reverse gear. Back under in the lowest reverse gear, slowly, so the kingpin isn't struck hard. Stop once the kingpin locks into the fifth wheel. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

D: Raise the landing gear slightly off the ground and pull the tractor gently forward while the trailer brakes are still locked. Raise the landing gear slightly off the ground, then pull the tractor gently forward with the trailer brakes still locked to make sure the trailer is locked on. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

A: So no one else moves the truck while you are under it. Secure the vehicle: neutral, parking brakes on, engine off, and take the key so someone else won't move the truck while you are under it. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

B: No space at all. There should be no space between the upper and lower fifth wheel. If there is, something is wrong and the trailer could come loose very easily. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

C: The shank of the kingpin. The jaws should wrap around the kingpin's shank, not its head. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

B: That the locking lever is in the 'lock' position and the safety latch is over it. Check that the locking lever is in the 'lock' position and the safety latch is in position over it. On some fifth wheels the catch must be set by hand. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-8.

C: Don't drive the coupled unit; get it fixed. A coupling that isn't right must be repaired before the unit is driven. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-9.

A: That it is plugged in with the safety catch fastened, and that the air and electrical lines won't hit moving parts. Plug in the electrical cord and fasten the safety catch, check the air and electrical lines for damage, and make sure they won't hit any moving parts. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-9.

D: Start in the low gear range; once the gear is free of weight, switch to high, and raise it all the way up. Use the low gear range to begin raising the landing gear, then switch to high once it is free of weight, and raise it all the way up. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.1 Coupling Tractor-Semitrailers, page 6-9.

A: That it can support the weight of the trailer. Make sure the surface of the parking area can support the weight of the trailer, and line up the tractor with the trailer. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.2 Uncoupling Tractor-Semitrailers, page 6-9.

C: Pulling out at an angle can damage the landing gear. Line the tractor up straight with the trailer, because pulling away at an angle can damage the landing gear. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.2 Uncoupling Tractor-Semitrailers, page 6-9.

B: Shut off the trailer air supply, back up gently, and set the parking brakes while the tractor pushes against the kingpin. Shut off the trailer air supply to lock the trailer brakes, back up gently to ease pressure on the jaws, and set the parking brakes while the tractor is pushing against the kingpin. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.2 Uncoupling Tractor-Semitrailers, page 6-9.

C: Turn the crank in low gear a few extra turns to lift some weight off the tractor, without lifting the trailer off the fifth wheel. For a loaded trailer, turn the crank a few extra turns in low gear to lift some weight off the tractor (but not off the fifth wheel). This makes it easier to unlatch the fifth wheel and to couple next time. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.2 Uncoupling Tractor-Semitrailers, page 6-9.

B: Connect the glad hands to dummy couplers (or together) and hang the electrical cable with the plug down. Connect the glad hands to dummy couplers at the back of the cab or couple them together, hang the electrical cable plug-down to keep moisture out, and support the lines so they won't be damaged. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.2 Uncoupling Tractor-Semitrailers, page 6-9.

C: Keep your legs and feet clear of the rear tractor wheels in case the vehicle moves. Stay clear of the tractor's rear wheels when you open the fifth wheel, so you aren't hurt if the rig moves. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.2 Uncoupling Tractor-Semitrailers, page 6-9.

C: It keeps the trailer from falling to the ground if the landing gear collapses or sinks. Stop with the tractor frame under the trailer; this prevents the trailer from falling to the ground if the landing gear collapses or sinks. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.2 Uncoupling Tractor-Semitrailers, page 6-9.

D: That the ground is supporting the trailer and the landing gear isn't damaged. Inspect the trailer supports: make sure the ground is supporting the trailer and the landing gear is not damaged. Then release the parking brakes, check the area, and drive clear. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.2 Uncoupling Tractor-Semitrailers, page 6-10.

D: For worn, damaged, or missing parts, and that the mount is secure. Inspect the pintle hook for worn, damaged, or missing parts and make sure the mount is secure; an unsecured pintle hook could separate from the vehicle. Commercial Driver's License Manual (CDL Driver's Manual): 6.4.3 Coupling a Pintle Hook, page 6-10.