JLG 4013PS Service Manual - Manual (Page 36)

Boom
3-4 3508PS, 3509PS, 3512PS, 3513PS, 4008PS, 4009PS, 4012PS, 4013PS, 4017PS, 40.8, 40.9
3.2 BOOM SYSTEM - TWO AND THREE
SECTION BOOM
3.2.1 Boom System Description
The boom operates via an interchange among the
electrical, hydraulic and mechanical systems. Components
involved include the joystick, tilt cylinder, extend/retract
cylinder, lift/lower cylinder, compensation cylinder,
electronic sensors, various pivots, supporting hardware
and other components.
3.3 BOOM ASSEMBLY MAINTENANCE -
TWO AND THREE SECTION BOOM
Note: Boom replacement must be completed in
sequence, one boom section at a time, as described in
these instructions.
Before beginning, conduct a visual inspection of the
machine and work area, and review the task about to be
undertaken. Read, understand and follow these
instructions.
3.3.1 Boom Removal
1. Remove any attachment from the quick switch
assembly. Refer to Section 3.11.1, “Connecting with
a Mechanical Quick Switch Device.”
Note: If replacing the innermost boom section, remove
the quick switch assembly. Refer to Section 3.11.4,
“Quick Switch Removal.”
2. Park the machine on a hard, level surface. Be sure
there is enough room in front of the machine to allow
the boom sections to be removed.
3. Fully retract the boom then raise the boom to access
the rod end pin of the lift/lower cylinder. Place the
transmission control lever in (N) NEUTRAL, engage
the park brake and shut the engine OFF.
4. Place a Do Not Operate Tag on both the ignition key
switch and steering wheel stating that the machine
should not be operated.
5. Open the engine cover. Allow the system fluids to
cool.
6. Properly disconnect the battery.
7. Relieve any trapped pressure in the tilt hydraulic
system by using the handle or wrench (located in the
toolbox) and move the double nut on the side of the
actuator module on the tilt valve section back and
forth. Repeat on the auxiliary valve section and on
the extend/retract section.
8. Label, disconnect and cap hydraulic hoses attached
the hose rack at the left rear corner of the boom.
9. Disconnect the boom angle indicator rod from the
switch at the inside left corner of the main boom
section and frame. Refer to Section 9.14.7, “Boom
Angle Sensor.”
10. Support the front of the boom by placing a sling
behind the boom head. Support the lift/lower cylinder
and remove the lock bolt and then the rod end pin.
Lower the lift/lower cylinder onto the frame rails.
11. Lower the boom to a level position and place a
suitable support under the boom head. Reposition
the slings to each end of the boom.
12. Remove the lock bolt and pin from the compensation
cylinder on each side of the first boom section.
Remove the lock bolt and pivot pin from rear of first
boom section.
13. Lift the complete boom off machine and set on level
ground or supports being careful not to damage the
tubes on the side of the first boom section.
a. If the boom is going to be disassembled after
removal:
1. Set the complete boom on level ground and by
repositioning the slings, turn boom over on to the top
side. Set the complete boom on suitable stands to
begin teardown.
Note: With the complete boom setting upside down, the
other boom section(s), tilt cylinder and hoses are made
more accessible.
2. Remove the access panel from the boom head.
3. Label, disconnect and cap the hoses attached to the
tilt cylinder and the hose rack on the side of the first
boom section.
4. Attach a sling through the rod end of the tilt cylinder.
Remove the clip from the barrel end of the tilt
cylinder pin. Remove the tilt cylinder pin and lift the
tilt cylinder out of the boom head.
5. Remove the hose clamp inside the innermost boom
section.
6. Label, disconnect and cap the hoses attached to the
extend/retract cylinder at the rear of the boom.