Oshkosh JLG 1500SJ, Service And Maintenance Manual

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SECTION 5 - BASIC HYDRAULIC INFORMATION & HYDRAULIC SCHEMATICS
5-148 – JLG Lift – 3121262
10. Remove the spring disc.
11. Remove the adjusting springs (two springs, one
”nested” inside the other) and spring follower.
12. The flow regulation spool should slide from the control
housing, (a magnet should aid in removal). If it does not,
remove the hollow hex head plug at the rear of the flow
regulation spool and carefully push the spool from the
housing - do not scratch/mar the spool’s bore.
13. Remove the spring cover hex cap for the ”inner” pres-
sure compensation adjustment – this requires a 30-mm
wrench.
14. Remove the spring disc.
15. Remove the adjusting springs (two springs, one
”nested” inside the other).
16. Remove the spring follower.
17. The pressure compensation spool should slide from the
control housing, (a magnet should aid in removal). If it
does not, remove the hollow hex head plug at the rear
of the flow regulation spool and carefully push the spool
from the housing - do not scratch/mar the spool’s bore.
18. The spools are identical.
19. Wash the housing and all parts in a clean JLG approved
solvent such as non-chlorinated brake cleaner, Stoddard
solvent, etc.
20. Blow off all the parts with clean, dry compressed air.
21. Inspect the housing for contamination or plugged ori-
fices. Clean orifices carefully with a
dead soft steel wire
to insure they are open. Inspect all parts for burrs, scor-
ing, debris, etc.
NOTE: On the mounting surface of the control housing, between
the oil ports is what appears to be a slotted head screw. IT
IS NOT A SCREW. This is a bleed orifice, which must be ori-
entated to allow proper control operation. The slot in the
head should be oriented to fall in-line with the oil ports,
NOT PERPENDICULAR to the oil ports. If the slot is oriented
perpendicular to the three ports, the pump pressure will
not return from load pressure to stand-by pressure at the
end of operating a function! The pump pressure will
remain at the last highest pressure generated.)
22. After all parts are clean and dry, lightly oil a control
spool and install in its bore. The spool must slide
smoothly and easily within the housing. If it does not,
check for contamination. If contamination cannot be
found check for ”scoring” or ”burring” of the control
housing. If the spool does not slide smoothly & freely,
the control must be replaced with a new unit.
23. Lightly oil and check operation of the second spool. The
spools are installed correctly when there ”pointed” end
faces the spring followers
24. Re-assemble in reverse order.
25. Bench set the pressure adjustments as described in ”C.
4” of the Operating Instructions.
NOTE: The pump control can be equipped with either O-rings or a
sealing plate. These components are NOT interchangeable.
26. Re-install on the Function Pump, insure the ”0”-rings are
installed properly and tighten the four (4) M6 socket
head cap screws to 105 inch pounds.