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


7–29



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 Retracting the Stabilizers

7–48


• Return selector valve to neutral position.

• Disengage PTO system.• Return stabilizer pads and stow

them in their appropriate storage location.

Procedure for Retracting the Stabilizers

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


Deploy, lock, unlock, and raise hydraulic stabilizers on laterally uneven terrain.



7–56


Deploy, lock, unlock, and raise 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


(Continued)

7–61



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


Education

Chapter 07