JLG 19BD Service Manual - Manual (Page 28)

SECTION 2 - SERVICE PROCEDURES
2-6 – JLG Lift – 3121154
Bolt Usage and Torque Application
Use bolts of proper length. A bolt which is too long will
bottom before the head is tight against its related part. If a
bolt is too short, there will not be enough thread area to
engage and hold the part properly. When replacing bolts,
use only those having the same specifications of the origi-
nal, or one which is equivalent.
Unless specific torque requirements are given within the
text, standard torque values should be used on heat-
treated bolts, studs, and steel nuts, in accordance with
recommended shop practices. (See Torque Chart in Sec-
tion-1 of this manual.)
Hydraulic Lines and Electrical Wiring
Clearly mark or tag hydraulic lines and electrical wiring, as
well as their receptacles, when disconnecting or removing
them from the unit. This will assure that they are correctly
reinstalled.
Hydraulic System
Keep the system clean. If evidence of metal or rubber par-
ticles is found in the hydraulic system, drain and flush the
entire system.
Disassemble and reassemble parts on clean work sur-
face. Clean all metal parts with non-flammable cleaning
solvent. Lubricate components, as required, to aid assem-
bly.
Lubrication and Servicing
Components and assemblies requiring lubrication and
servicing are shown in the Lubrication Chart, (See Sec-
tion-1). Service applicable components with the amount,
type, and grade of lubricant recommended in this manual,
at the specified intervals. When recommended lubricants
are not available, consult your local supplier for an equiva-
lent that meets or exceeds the specifications listed.
Mast Chain Inspection Procedure
MAST CHAINS TO BE INSPECTED AND LUBRICATED EVERY
THREE MONTHS OR 5 HOURMETER HOURS.
Inspect mast chains for the following conditions:
Wear: Always inspect that segment of chain that operates
over a sheave. As the chain flexes over the extend/retract
sheaves, joints and plate edges very gradually wear.
Chain “stretch” can be measured using a manufacturers
wear scale or steel tape. When chains have elongated 3%
they must be removed and replaced. Refer to Table 2-3 for
proper chain specifications and allowable stretch toler-
ances. Peening and wear of chain plate edges are caused
by sliding over a chain worn contact face of a sheave, or
unusually heavy loads. All of the above require replace-
ment of the chain and correction of the cause. Chain side
wear, noticeable when pin heads and outside plates show
a definite wear pattern, is caused by misalignment of the
sheave/chain anchors and must be corrected promptly.
Do not repair chains; if a section of chain is damaged,
replace the entire chain set.
Rust and Corrosion: Rust and corrosion will cause a
major reduction in the load carrying capacity of the chain,
because these are primary reasons for side plate crack-
ing. The initial lubrication at the factory is applied in a hot
dip tank to assure full penetration into the joint. Do not
steam clean or degrease chains. At time of chain installa-
tion, factory lube must be supplemented by a mainte-
nance program to provide a film of oil on the chains at all
times. If chains are corroded, they must be inspected,
especially the outside plates, for cracks in-line with the
pins. If cracks are found, replace the chain; if no cracks
are discovered, lubricate the chains by dipping in heated
oil, and reinstall on the machine. Keep chains lubricated.
H
5% of H
Example:
H for a 1" chain = 0.950"
Maximum Wear = 5% of 0.950 = 0.047"
Minimum Plate Depth = 0.950" - 0.047 = 0.903"