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JLG Lift
SECTION 9- TROUBLESHOOTING
JLG
Lift
9-1.
GENERAL
This section contains troubleshooting information to
be used for locating and correcting most of the oper-
ating problems which may develop in the aerial plat-
form. If a problem should develop which is not pre-
sented in this section or which is not corrected by
listed corrective actions, technically qualified guid-
ance should be obtained before proceeding with any
maintenance.
9-2.
TROUBLESHOOTING INFORMATION
The troubleshooting procedures applicable to the
aerial platform are listed and defined in Tables 9-1,
AC Unit Troubleshooting and 9-2, DC Unit Trou-
bleshooting.
Each malfunction within an individual group or sys-
tem is followed by a listing of probable causes which
will enable determination of the applicable remedial
action. The probable causes and the remedial action
should, where possible, be checked in the order
listed in the tables.
It should be noted that there is no substitute for a
thorough knowledge of the equipment and related
systems.
It should be recognized that the majority of the prob-
lems arising in the machine will be centered in the
hydraulic and electrical systems. For this reason,
every effort has been made to ensure that all likely
problems in these areas are given the fullest possible
treatment. In the remaining machine groups, only
those problems which are symptomatic of greater
problems which have more than one probable cause
and remedy are included. This means that problems
for which the probable cause and remedy may be
immediately obvious are not listed in this section.
The first rule for troubleshooting any circuit that is
hydraulically operated and electrically controlled is to
determine if the circuit is lacking hydraulic oil and
electrical control power. This can be ascertained by
overriding the bypass valve (mechanically or electri-
cally) so that oil is available to the function valve, then
overriding the function valve mechanically. If the
function performs satisfactorily, the problem exists
with the control circuit.
9-3.
HYDRAULIC CIRCUIT CHECKS
(See Figure 9-2.)
The first reference for improper function of a hydrau-
lic system, where the cause is not immediately appar-
ent, should be the Troubleshooting Chart. The best
place to begin the problem analysis is at the power
source (pump). Once it is determined that the pump
is serviceable, then a systematic check of the circuit
components, beginning with the control, would fol-
low.
Note
For aid in Hydraulic troubleshooting, refer to Figure
9-2. Hydraulic Diagram at the end of this section.
Refer to the Illustrated parts list Section 10-7. for
ELECTRICAL DIAGRAMS of the various circuits.
9-4.
OUTRIGGER INTERLOCK CONTACTS
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m~~i~~er·s~~etirid.··oy~rigg6; e6~nl·.-
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Interlock
Cori~acts
.···· · . · . · . ·
· .
It is very important that the outrigger iAterlock
contactor heads (round) on the bottom of the
outrigger sockets of the base frame and the con-
tactor plate on the bottom of each outrigger beam
are installed properly, (see Figure 9-1. for correct
installation). Also see Troubleshooting Tables 9-
1. & 9-2. for any further reference to possible
problems with interlock contacts.
• • · · •
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!1Qfll£tlling
1nstrue~9ns
• • • . •
. · · · ·
(See Figure 9-1.)
1.
Install insulating grommets into holes (on the
bottom) inside of outrigger sockets in base
frame.
2.
Assemble two (2) #8-32UNC x 5/8" long con-
tactor screws with two (2) #8 nylon washers
under head and insert screw through insulating
grommet as shown in Figure 9-1 .
3. Install one {1) #8 nylon washer onto contactor
screw threads against insulating grommet.
4.
Apply Loctite #242 to screw threads.
5.
Install one {1) standard #8 brass nut and thread
in against nylon washer until insulating grom-
met
just starts to compress. If necessary
tighten nut further until top of contactor screw
head measures 0.212" off floor of outrigger
socket. (See Figure 9-1.}
-JLGUft-
Updated - 5/97
9-1
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