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Step 8. Secure Tractor
Apply parking brake.
Place transmission in neutral.
Step 9. Inspect Trailer Supports
Make sure ground is supporting trailer.
Make sure landing gear is not damaged.
Step 10. Pull Tractor Clear of Trailer
Release parking brakes.
Check the area and drive tractor forward until it
clears.
Subsections 6.3 and 6.4
Test Your Knowledge
1. What might happen if the trailer is too high when
you try to couple?
2. After coupling, how much space should be
between the upper and lower fifth wheel?
3. You should look into the back of the fifth wheel
to see if it is locked onto the kingpin. True or
False?
4. To drive you need to raise the landing gear only
until it just lifts off the pavement. True or False?
5. How do you know if your trailer is equipped with
antilock brakes?
These questions may be on your test. If you can’t
answer them all, re-read subsections 6.3 and 6.4.
Lift the lock handle away from the vehicle until the
lock clears the lock seat on the hook body.
Open the latch by rotating the latch assembly up
toward the vehicle until the latch is in its most
upright position, then release the lock handle.
(Figure 17 and 18)
.
6.4.3 - Coupling a Pintle Hook
Step 1. Inspect Pintle Hook
Before operating, check for worn, damaged, or
missing parts, and make sure mount is secure. If
the pintle hook is not secured to the mounting
surface, the pintle hook could separate from the
vehicle which, if not avoided, could result in death
or serious injury.
Step 2. Unlock Lock Pin and Open Latch
Unlock and remove the tethered lock pin, if
applicable (Figure 16).
Step 3. Lower Drawbar into Place
Position the drawbar eye over the horn of the pintle
hook and lower it into place.
Step 4. Lock Pintle Hook
Push the latch closed. When correctly locked, the
lock handle will rotate and move up until it is flush
with the top of the latch (Figure 19).
Section 6 - Combination Vehicles Page 6-10
Version: July 2017
Commercial Driver’s License Manual – 2005 CDL Testing System
6.4.5 - Coupling a Drawbar
Insert the tethered lock pin through the latch and
lock holes, and close the tethered wire lock pin, if
applicable (Figure 16).
Failure to correctly lock the latch can result in
separation of the trailer and vehicle which, if not
avoided, could result in death or serious injury.
6.4.4 - Uncoupling a Pintle Hook
Step 1. Park on Level Surface
Park the trailer on a firm level surface and block
trailer tires.
Step 2. Disconnect Electrical Connector,
Breakaway Brake Switch and Safety Chains
Disconnect electrical connector.
Disconnect breakaway brake switch lanyard.
Disconnect safety chains from tow vehicle.
Step 3. Unlock the Coupler
Unlock the coupler and open it.
Step 4. Check Ground Surface for Correct
Support
Before extending jack, make certain the ground
surface below the jack pad will support the tongue
load.
Step 5. Rotate Jack Handle
Rotate jack handle to extend the jack and transfer
the weight of the trailer tongue to the jack.
Step 6. Raise Trailer Coupler
Raise the trailer coupler above the tow vehicle
hitch.
Step 7. Drive Forward
Drive tow vehicle forward.
Step 1. Remove Safety Lock screw and Rotate
Safety Cover Bar
Remove safety lock screw (2), recover and keep
the relative self-locking nut (12) aside then also
loosen safety lock screw (2a) and turn out the
adjustment screw (3) by at least five turns.
Rotate the safety cover bar (4) outwards so that it
is completely open.
Step 2. Reverse Truck
Reverse truck very slowly until the ball cup
drawbar eye (6) is in position exactly above the
drawbar coupling ball (5).
Step 3. Lower the Drawbeam
Lower the drawbeam until the ball cup drawbar eye
(6) lies completely covering the drawbar coupling
ball (5).
Step 4. Rotate the Safety Cover Bar
Rotate the safety cover bar back inwards (4) and fit
in safety lock screw (2) together with its self-
locking nut.
Tighten in both the lock screws (2, 2a) together
with their relative self-locking nuts (12, 12a) at a
350 to 400 Nm torque wrench setting.
Step 5. Adjust the Adjustment Screw
Adjust the adjustment screw (3) until a 0.3 - 0.5
mm vertical clearance between the guard disk (13)
and the ball cup (6) is reached. Lock setting with
counter nut (11).
Section 6 - Combination Vehicles Page 6-11
Version: July 2017
Commercial Driver’s License Manual – 2005 CDL Testing System
In the event that the safety cover bar (4) will not
perfectly lodge into its seating appropriately, travel
is strictly forbidden.
Step 6. Protect Coupling Ball and Anchor Edge
onto Ball
Protect the part that is still visible of the coupling
ball (5) with the rubber dust proof bellows
protection cover (7). Accurately anchor the edge
directly onto the ball itself.
Step 7. Lubricate the Drawbar Eye
Lubricate the inside of the drawbar eye ball cup (6)
directly through the grease nipple (18).
6.4.6 - Uncoupling a Drawbar
Step 1. Turn Trailer Brake On
Make sure that the trailer brake is
on.
Step 2. Remove Cover and Loosen Screws
Remove the rubber dust proof bellows protection
cover (7).
Loosen the adjustment screw (3) and the counter
nut (11).
Loosen safety lock screw (2a) and remove safety
lock screw (2) together with its self-locking nut
(12).
Step 3. Rotate Safety Cover Bar and Lift Trailer
Drawbeam
Rotate the safety cover bar (4) outwards so that it
is completely open.
Lift the trailer drawbeam until the drawbar coupling
ball (5) is fully visible, then travel forward with the
trailer very slowly.
Rotate the safety cover bar inwards (4) until it
lodges back in its housing.
Step 4. Lock Safety Screw and Tighten Self-
Locking Nut
Fit in safety lock screw (2) and tighten in self-
locking nut (12).
6.4.7 - Coupling a Gooseneck Hitch
If you are hooking up a Gooseneck or a fifth wheel
hitch, the procedure is a little different from a
receiver and ball, but it is not more difficult.
Step 1. Open the Latch and Lubricate the
Gooseneck Ball
Open the clamp latch on the Gooseneck coupler.
Make sure that the Gooseneck ball is properly
lubricated.
Step 2. Position Coupler and Latch the Clamp
Position the trailer's coupler directly over the ball
and lower the Gooseneck trailer into position and
latch the clamp.
Step 3. Attach Safety Chains
Attach your safety chains. Remember that all
trailers are required by law to have safety chains.
Step 4. Connect Trailer Light Wiring
Connect your trailer light wiring to your vehicle's
connector.
Check all of your lights, including your brake lights.
Step 5. Lower and Stow the Trailer Jacks
Completely lower and stow the trailer jacks,
allowing the weight to settle onto the tow vehicle.
6.4.8 Uncoupling a Gooseneck Hitch
Step 1. Remove Safety Pin and Clip
Simply remove safety pin and clip.
Step 2. Rotate Handle and Raise Trailer Off Ball
Rotate handle to this position (Fig. B) and raise
trailer off ball. Coupler will return to load position
automatically.
Step 3. Install Safety Pin and Clip
Install safety pin and clip. (Fig. B)
Section 6 - Combination Vehicles Page 6-12
Version: July 2017
Commercial Driver’s License Manual – 2005 CDL Testing System
6.5 – Inspecting a Combination Vehicle
Use the seven-step inspection procedure described
in Section 2 to inspect your combination vehicle.
There are more things to inspect on a combination
vehicle than on a single vehicle. (For example, tires,
wheels, lights, reflectors, etc.) However, there are
also some new things to check. These are
discussed below.
6.5.1 – Additional Things to Check during a
Walk-around Inspection
Do these checks in addition to those already listed
in Section 2.
Coupling System Areas
Check fifth wheel (lower).
Securely mounted to frame.
No missing or damaged parts.
Enough grease.
No visible space between upper and lower fifth
wheel.
Locking jaws around the shank, not the head of
kingpin. See Figure 6.8.
Release arm properly seated and safety
latch/lock engaged.
Figure 6.8
Check fifth wheel (upper).
Glide plate securely mounted to trailer frame.
Kingpin not damaged.
Air and electric lines to trailer.
Electrical cord firmly plugged in and secured.
Air-lines properly connected to glad hands, no air
leaks, properly secured with enough slack for turns.
All lines free from damage.
Sliding fifth wheel.
Slide not damaged or parts missing.
Properly greased.
All locking pins present and locked in place.
If air powered--no air leaks.
Check that fifth wheel is not so far forward that
tractor frame will hit landing gear, or the cab hit the
trailer, during turns.
Landing Gear
Fully raised, no missing parts, not bent or
otherwise damaged.
Crank handle in place and secured.
If power operated, no air or hydraulic leaks.
Section 6 - Combination Vehicles Page 6-13
Version: July 2017
Commercial Driver’s License Manual – 2005 CDL Testing System
6.5.2 – Combination Vehicle Brake Check
Do these checks in addition to Section 5.3:
Inspecting Air Brake Systems.
The following section explains how to check air
brakes on combination vehicles. Check the brakes
on a double or triple trailer as you would any
combination vehicle.
Check That Air Flows to All Trailers. Use the
tractor parking brake and/or chock the wheels to
hold the vehicle. Wait for air pressure to reach
normal, then push in the red "trailer air supply" knob.
This will supply air to the emergency (supply) lines.
Use the trailer handbrake to provide air to the
service line. Go to the rear of the rig. Open the
emergency line shut-off valve at the rear of the last
trailer. You should hear air escaping, showing the
entire system is charged. Close the emergency line
valve. Open the service line valve to check that
service pressure goes through all the trailers (this
test assumes that the trailer handbrake or the
service brake pedal is on), and then close the valve.
If you do NOT hear air escaping from both lines,
check that the shut-off valves on the trailer(s) and
dolly(ies) are in the OPEN position. You MUST have
air all the way to the back for all the brakes to work.
Test Tractor Protection Valve. Charge the trailer
Air-brake system. (That is, build up normal air-
pressure and push the "air supply" knob in.) Shut
the engine off. Step on and off the brake pedal
several times to reduce the air pressure in the tanks.
The trailer air supply control (also called the tractor
protection valve control) should pop out (or go from
"normal" to "emergency" position) when the air
pressure falls into the pressure range specified by
the manufacturer. (Usually within the range of 20 to
45 psi.)
If the tractor protection valve doesn't work right, an
air hose or trailer brake leak could drain all the air
from the tractor. This would cause the emergency
brakes to come on, with possible loss of control.
Test 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.
Test Trailer Service Brakes. Check for normal air
pressure, release the parking brakes, move the
vehicle forward slowly, and apply trailer brakes with
the hand control (trolley valve), if so equipped. You
should feel the brakes come on. This tells you the
trailer brakes are connected and working. (The
trailer brakes should be tested with the hand valve
but controlled in normal operation with the foot
pedal, which applies air to the service brakes at all
wheels.)
Subsection 6.5
Test Your Knowledge
1. Which shut-off valves should be open and
which closed?
2. How can you test that air flows to all trailers?
3. How can you test the tractor protection valve?
4. How can you test the trailer emergency brakes?
5. How can you test the trailer service brakes?
These questions may be on your test. If you can’t
answer all of them, re-read subsection 6.5.
Section 6 - Combination Vehicles Page 6-14
Version: July 2017
Commercial Driver’s License Manual – 2005 CDL Testing System
Section 7
DOUBLES AND TRIPLES
This Section Covers
• Pulling Double/Triple Trailers
• Coupling and Uncoupling
• Inspecting Doubles and Triples
• Checking Air Brakes
This section has information you need to pass the
CDL knowledge test for driving safely with double
and triple trailers. It tells about how important it is to
be very careful when driving with more than one
trailer, how to couple and uncouple correctly, and
about inspecting doubles and triples carefully. (You
should also study Sections 2, 5, and 6.)
7.1 – Pulling Double/Triple Trailers
Take special care when pulling two and three
trailers. There are more things that can go wrong,
and doubles/triples are less stable than other
commercial vehicles. Some areas of concern are
discussed below.
7.1.1 – Prevent Trailer from Rolling Over
To prevent trailers from rolling over, you must steer
gently and go slowly around corners, on ramps, off
ramps, and curves. A safe speed on a curve for a
straight truck or a single trailer combination vehicle
may be too fast for a set of doubles or triples.
7.1.2 – Beware of the Crack-the-whip Effect
Doubles and triples are more likely to turn over than
other combination vehicles because of the "crack-
the-whip" effect. You must steer gently when pulling
trailers. The last trailer in a combination is most
likely to turn over. If you don't understand the crack-
the-whip effect, study subsection 6.1.2 of this
manual.
7.1.3 – Inspect Completely
There are more critical parts to check when you
have two or three trailers. Check them all. Follow
the procedures described later in this section.
7.1.4 – Look Far Ahead
Doubles and triples must be driven very smoothly to
avoid rollover or jackknife. Therefore, look far ahead
so you can slow down or change lanes gradually
when necessary.
7.1.5 – Manage Space
Doubles and triples take up more space than other
commercial vehicles. They are not only longer, but
also need more space because they can't be turned
or stopped suddenly. Allow more following distance.
Make sure you have large enough gaps before
entering or crossing traffic. Be certain you are clear
at the sides before changing lanes.
7.1.6 – Adverse Conditions
Be more careful in adverse conditions. In bad
weather, slippery conditions, and mountain driving,
you must be especially careful if you drive double
and triple bottoms. You will have greater length and
more dead axles to pull with your drive axles than
other drivers. There is more chance for skids and
loss of traction.
7.1.7 – Parking the Vehicle
Make sure you do not get in a spot you cannot pull
straight through. You need to be aware of how
parking lots are arranged in order to avoid a long
and difficult escape.
7.1.8 – Antilock Braking Systems on Converter
Dollies
Converter dollies built on or after March 1, 1998, are
required to have antilock brakes. These dollies will
have a yellow lamp on the left side of the dolly.
7.2 – Coupling and Uncoupling
Knowing how to couple and uncouple correctly is
basic to safe operation of doubles and triples.
Wrong coupling and uncoupling can be very
dangerous. Coupling and uncoupling steps for
doubles and triples are listed below.
7.2.1 – Coupling Twin Trailers
Secure Second (Rear) Trailer
If the second trailer doesn't have spring brakes,
drive the tractor close to the trailer, connect the
emergency line, charge the trailer air tank, and
disconnect the emergency line. This will set the
trailer emergency brakes (if the slack adjusters are
correctly adjusted). Chock the wheels if you have
any doubt about the brakes.
For the safest handling on the road, the more
heavily loaded semitrailer should be in first position
behind the tractor. The lighter trailer should be in the
rear.
Section 7 - Doubles and Triples Page 7-1
Version: July 2017
Commercial Driver’s License Manual – 2005 CDL Testing System
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