JLG 19AMI Service Manual - Manual (Page 21)

SECTION 2 - SERVICE PROCEDURES
3121190 – JLG Lift – 2-7
Tight Joints: All joints in the leaf chain should flex freely.
On leaf chains, tight joints are usually caused by rust/cor-
rosion, or the inside plates “walking” off the bushing. Lim-
ber up rusty/corroded chains (after inspecting carefully)
with a heavy application of oil (preferably a hot oil dip). Tap
inside “walking” plates inward; if “walking” persists,
replace the chain. This type of problem is accelerated by
poor lubrication maintenance practice, and most tight
joint chains have been operated with little or no lubrica-
tion. Tight joints on leaf chain are generally caused by:
a. Bent pins or plates.
b. Rusty joints.
c. Peened plate edges.
Oil rusty chains, and replace chains with bent or peened
chain components. Keep chains lubricated.
Protruding or Turned Pins: Chains operating with inade-
quate lube generate tremendous friction between the pin
and plates (pin and bushing on leaf chain). In extreme
cases, this frictional torque can actually turn the pins in
the outside press-fit plates. Inspect for turned pins, which
can be easily spotted as the “V” flats on the pin heads are
no longer in line. Replace all chains showing evidence of
turned or protruding pins. Keep chains lubricated.
Chain Anchors and Sheaves: An inspection of the chain
must include a close examination of chain anchors and
sheaves. Check chain anchors for wear, breakage and
misalignment. Anchors with worn or broken fingers should
be replaced. They should also be adjusted to eliminate
twisting the chain for an even load distribution.
Inspect the sheaves, sheave bearings, sheave grooves
and pins for extreme wear, replace as necessary. A worn
sheave can mean several problems, as follows:
a. Chains too tight.
b. Sheave bearings/pin bad.
c. Bent/misaligned chains.
2.5 LUBRICATION INFORMATION
Hydraulic System
The primary enemy of a hydraulic system is contamina-
tion. Contaminants enter the system by various means,
e.g., using inadequate hydraulic oil, allowing moisture,
grease, filings, sealing components, sand, etc., to enter
when performing maintenance, or by permitting the pump
to cavitate due to insufficient system warm-up or leaks in
the pump supply.
The design and manufacturing tolerances of the compo-
nent working parts are very close, therefore, even the
smallest amount of dirt or foreign matter entering a system
can cause wear or damage to the components and gener-
ally results in faulty operation. Every precaution must be
taken to keep hydraulic oil clean, including reserve oil in
storage.
Cloudy oils indicate a high moisture content which per-
mits organic growth, resulting in oxidation or corrosion. If
this condition occurs, the system must be drained,
flushed, and refilled with clean oil.
It is not advisable to mix oils of different brands or types,
as they may not contain the same required additives or be
of comparable viscosities. Good grade mineral oils, with
viscosities suited to the ambient temperatures in which
the machine is operating, are recommended for use.
NOTE: Metal particles may appear in the oil of new
machines due to the wear-in of meshing compo-
nents.
Hydraulic Oil
For best performance, JLG recommends the use of ISO-
Vg grade 32, 46 oil with a viscosity range between 15-250
SUS at 100 degrees F (32-54 cST at 40 degrees C). Refer
to Section 1 for recommended hydraulic oils.
Changing Hydraulic Oil
Use of any of the recommended hydraulic oils eliminates
the need for changing the oil on a regular basis. If it is nec-
essary to change the oil, use only those oils meeting or
exceeding the specifications appearing in this manual. If
unable to obtain the same type of oil supplied with the
machine, consult local supplier for assistance in selecting
the proper equivalent. Avoid mixing petroleum and syn-
thetic base oils. JLG Industries recommends changing the
hydraulic oil annually.
Use every precaution to keep the hydraulic oil clean. If the
oil must be poured from the original container into
another, be sure to clean all possible contaminants from
the service container.
While the unit is shut down, a good preventive mainte-
nance measure is to make a thorough inspection of all
hydraulic components, lines, fittings, etc., as well as a
functional check of each system, before placing the
machine back in service.
Lubrication Specifications
Specified lubricants, as recommended by the component
manufacturers, are always the best choice, however,
multi-purpose greases usually have the qualities which
meet a variety of single purpose grease requirements.
Should any question arise regarding the use of greases in
maintenance stock, consult your local supplier for evalua-
tion. Refer to Table 1-2 in Section 1 for an explanation of
the lubricant key designations appearing in the Lubrica-
tion Chart.