Chapter 07

Aerial Apparatus
Driver/Operator Handbook
2nd Edition
Chapter 7 — Stabilizing the
Apparatus

Learning Objective 1
Discuss the basics of aerial device
hydraulic systems.
7–2
Aerial Apparatus Driver/Operator

DISCUSSION QUESTION
Why is the apparatus stabilization
process so critical?
7–3

• When parked, somewhere along
longitudinal midline of chassis, between
front and rear axles
• When aerial device extended over front
of apparatus, shifts toward front
• Shifts as aerial device is rotated
Center of Gravity
(Continued)
7–4

Center of Gravity
7–5

Effect of Stabilizers
7–6

Effect of Extensions
7–7

Effect of Rotation
7–8

Effect of Short-Jacking
7–9

Effect of Slopes
7–10

Effect of Overloading
7–11

• Prevent apparatus from tipping as aerial
device is extended away from
centerline of chassis
Stabilizers
7–12

Straight Jacks
7–13
Courtesy of Ron Jeffers

A-Frame
7–14
Photo by Ted Boothroyd

Box Stabilizers
7–15
Photo by Ted Boothroyd

Explain transferring power to the
hydraulic system.
7–16

• Must be engaged to deploy stabilizers
and aerial device
• Engaged by activating power take-off
(PTO) system
• Automatic transmission without fire
pump
Aerial Hydraulic System
(Continued)
7–17

• Manual transmission without fire pump
• Automatic transmission with fire pump
in use
• Manual transmission with fire pump in
use
Aerial Hydraulic System
7–18

Transfer power to the hydraulic system
of an apparatus equipped with a fire
pump.
Objective 3 is measured in Skill Sheet 7-1.
7–19

Transfer power to the hydraulic system
of an apparatus not equipped with a fire
pump.
7–20

Discuss setting and raising stabilizers.
7–21

• PTO engagement light is on
• Wheels properly chocked
• Stabilizers do not strike or land on
objects
• Check stabilizers when they are in
place
• Icy patches or frozen ground
Preliminary Checks
7–22

• Operated once preliminary activities are
successfully completed
• Provides hydraulic power to stabilizing
system
• Located on rear step or midship on
driver’s side
• Operation
Operating the Selector Valve
7–23

• Ideal situation for stabilization
• Maximum stability
Stabilizing on Even Terrain
7–24

• Many are lever-type valves
• Engine idle speed is regulated
• When driver/operator operates control,
increase in engine speed occurs
• Rough and jerky operation should be
avoided
Stabilizer Controls
7–25

• Extend straight down
• Fulcrum-types swing down into position
• Box types first extend outward and then
down
Positioning of Stabilizers
7–26

• Extend parallel extension arms to their
maximum travel distance
• Center portable stabilizer pads
• Lower stabilizing jacks
• Lower both stabilizers on one side
• Lower stabilizers onto pads
Operation of
Box Type Stabilizers
7–27

DISCUSSION QUESTION
What is a good way to judge
appropriate deployment of the
stabilizers?
7–28

• Lower stabilizers on the other side
• Alternate between sides to raise the
vehicle to working position, as close to
level as possible
Operation of
7–29

Operation of
7–30

DISCUSSION QUESTION
How much should the apparatus be
raised?
7–31

• Similar to box-type
• Exception – Should be lowered to within
a few inches of ground prior to the
placement of stabilizer pads
Operation of
Fulcrum-Type Stabilizers
7–32

• Unavoidable in some situations
• Lateral unevenness
• Longitudinal unevenness
Stabilizing on Uneven Terrain
7–33

Lateral Unevenness
(Continued)
7–34

Lateral Unevenness
(Continued)
7–35

Lateral Unevenness
(Continued)
7–36

Lateral Unevenness
7–37

DISCUSSION QUESTION
What does a 5 percent grade mean?
7–38

5 Percent Grade
7–39

Longitudinal Unevenness
7–40

7–41

7–42

• Avoided whenever
possible
• Treat same as
setting up on
lateral incline
Stabilizing on Curbs or
Other Obstructions
7–43
Courtesy of Ron Jeffers

Discuss locking the stabilizers.
7–44

• Combination of hydraulic system
holding valves and interlock feature
• Indicator light
• Box-type stabilizers
Locking the Stabilizers
7–45

Discuss retracting the stabilizers.
7–46

• After use of aerial device is complete
and it is returned to the bed
• Reverse of stabilization process
• Prepares apparatus for departure from
the scene
Retracting the Stabilizers
7–47

• Remove safety pins from jacks.
• Return selector valve to stabilization
position.
• Move wheel chocks.
• Check around apparatus.
• Raise stabilizers.
Procedure for
7–48

• Return selector valve to neutral
position.
• Disengage PTO system.
• Return stabilizer pads and stow them in
their appropriate storage location.
Procedure for
7–49

Explain manual stabilizers.
7–50

• Still in use on older apparatus
• Similar to box-type hydraulic stabilizers
• Consist of extension arm that has a
screw jack attached to the end of arm
• Extension arm must be swung into
position by hand
Manual Stabilizers
(Continued)
7–51

• Placing stabilizers on midship aerials in
service
• Placing stabilizers on tractor-trailer
aerials in service
Manual Stabilizers
(Continued)
7–52

Manual Stabilizers
(Continued)
7–53

Manual Stabilizers
7–54

Deploy, lock, unlock, and raise
hydraulic stabilizers on even terrain.
7–55

hydraulic stabilizers on laterally uneven
terrain.
7–56

hydraulic stabilizers on longitudinally
uneven terrain.
7–57

Deploy, lock, and then unlock and stow
manual stabilizers.
7–58

Discuss stabilizing the tractor-trailer
aerial apparatus.
7–59

• Stability is given by manner it is parked
and positioned at scene
• Creating an angle between tractor and
trailer can increase stability
• Maximum stability occurs at 60 degrees
• Angles less than 60 degrees provide
less stability
Stabilizing Tractor-Trailer
Aerial Apparatus
(Continued)
7–60

• Degrees 61 to 90 provide less stability
• Should never be positioned at an angle
greater than 90 degrees
• Procedure for placing vehicle into
angled position
Aerial Apparatus
(Continued)
7–61

Aerial Apparatus
7–62

Stabilize tractor-trailer aerial apparatus.
7–63

Summary
• Because the suspension alone cannot
support the outboard weight of an
extended aerial device, effective
stabilization methods must be used.
(Continued)
7–64

• While the apparatus has built-in
stabilization hardware, the
driver/operator must understand the
dynamics of weight transfer and use
this understanding to optimize the
positioning of the apparatus before
stabilization is complete.
Summary
(Continued)
7–65

• Aerial apparatus are manufactured by
several different companies; therefore,
it is important for the driver/operator to
review the specifics of the stabilization
system and its limitations by continual
review of the operator’s manual.
Summary
7–66

Review Questions
1. What may be the most critical
aspect of preparing an aerial device
for use?
2. Why must apparatus stabilizers
be set prior to deploying an aerial
device?
3. Why would a driver/operator use
the practice of short-jacking? (Continued)
7–67

Review Questions
4. What is the purpose of the
power take-off (PTO) system?
5. What observations must be
made by the driver/operator prior to
deploying stabilizers?
6. Why is stabilization ideally
performed on even terrain?
(Continued)
7–68

7. In what three ways may
stabilizers move into position?
8. In what ways can an apparatus
be uneven?
9. How is a manual stabilizer put into
service on a midship aerial?
Review Questions
(Continued)
7–69

10. What is the best way to place a
tractor-trailer apparatus into an
angled position?
Review Questions
7–70

Chapter 07

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Chapter 07