JLG 740A, Service And Maintenance Manual

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SECTION 5 - HYDRAULICS
5-28 – JLG Lift – 3121160
4. Remove the plug (C103), O-ring (C103A),and Pres-
sure Compensator spool (C132) from the control
housing; discard the O-ring. Note orientation of the
spool for reassembly.
5. Remove the plug (C107) and O-ring (C107A); dis-
card the O-ring.
NOTE: For Pressure Compensator only controls, skip steps
6 and 7.
6. Remove the Load Sense set screw (C102), Load
Sense adjustment screw (C118), O-ring (C116),
back-up rings (C117), springs (C114, C115), and
seat (C113); discard the O-ring.
7. Remove the plug (C106), O-ring (C106A),and Load
Sense spool (C112) from the control housing; dis-
card the O-ring. Note orientation of the spool for
reassembly.
INSPECTION
1. Inspect the adjustment screws for wear at the tips
and where they contact the springs; replace as nec-
essary
2. Inspect the springs and spring guides for wear or
damage; replace as necessary.
3. Carefully inspect the spools. Ensure the sealing
lands are free of nicks and scratches. Check the
ends that contact the spring guides for wear.
Replace spools as necessary.
4. Inspect the control housing for damage. Check the
spool bores for excessive wear.
5. Clean all parts and lubricate spools, springs, guides
and new O-rings with clean hydraulic fluid.
REASSEMBLY
1. Install the Pressure Compensator spool, spherical
end first, into the Pressure Compensator bore. The
Pressure Compensator spool is the shorter of the
two. Using a new O-ring, install the plug (C103).
Torque to 8-10 ft.lb. [11-14 Nm].
2. Place the two Pressure Compensator springs onto
the spring guide and install into the Pressure Com-
pensator bore. Place a new O-ring onto the Pressure
Compensator adjustment screw and thread it into
the Pressure Compensator bore until flush, then
make another full turn. Install and torque the set
screw to 6-8 ft.lb. [7-11 Nm].
NOTE: For Pressure Compensator only controls, skip steps
15 and 16.
3. Install the Load Sense spool, spherical end first, into
the Load Sense bore. The Load Sense spool is the
longer of the two. Using a new O-ring, install the
plug (C106). Torque to 8-10 ft.lb. [11-14 Nm].
4. Place the two Load Sense springs onto the spring
guide and install into the Load Sense bore. Place a
new O-ring and backup rings onto the Load Sense
adjustment screw and thread it into the Load Sense
bore until flush, then make another full turn. Install
and torque the set screw to 6-8 ft.lb. [7-11 Nm].
5. Using a new O-ring, install the plug (C107). Torque
to 8-10 ft.lb. [11-14Nm].
6. Using petroleum jelly to retain them, install the three
interface O-rings (C200) in the recesses on the con-
trol housing.
7. Install the control assembly onto the endcap using
the four screws (C300). Torque to 11-13 ft.lb. [15-18
Nm].Torque screws in a criss-cross pattern and re-
torque the first screw to ensure proper torque reten-
tion.
8. Check and adjust the control setting. See Adjust-
ments.