JLG 510AJ Service Manual - Manual (Page 205)

SECTION 4 - BOOM AND PLATFORM
3121181 – JLG Lift – 4-7
4.2 ROTATOR
See Figure 4-5., Rotator Assembly - Cutaway
Disassembly and Inspection
1. Place on a clean workbench with room to place internal
parts as they are removed.
2. Remove all hydraulic fittings.
3. Loosen cap screws(7) and unscrew locknut (6) and end
cap (5). Shaft is now free to move up and out of engage-
ment with piston sleeve (3).
NOTE: Note orientation between spline teeth (see Figure 4-4.), as
this will greatly simplify actuator timing upon reassembly.
4. After removing shaft, piston sleeve and piston assembly
can be moved down and out of housing.
5. Remove all seals and bearings from their grooves,
except static piston seals (9) and (11). These seals gener-
ally do not require replacement.
6. Clean all parts thoroughly and inspect for wear.
7. A small amount of wear in spline teeth has little effect
on actuator strength. New spline sets are manufactured
with a backlash of about 0.005” (0.127 mm) per mating
set. After long service, a backlash of about 0.015” (0.381
mm) per set may still be acceptable in most cases,
depending on required accuracy of the application.
8. Item (1) is the integral housing and ring gear. Check the
ring gear for wear and weld damage to the pins. Inspect
the cylinder bore for wear and scratches. The surface fin-
ish should be 32 RMS or better; re-hone if necessary.
9. Radial bearings (18) and (19) and piston bearings (17)
should have a maximum radial clearance of 0.006”
(0.152 mm). A clearance in excess of 0.008” (0.203 mm)
requires replacement of bearings.
10. Rough and grooved shaft journals require shaft replace-
ment.
Assembly and Testing
1. Wash parts thoroughly in cleaning solvent and blow dry.
2. Coat all sealing and working surfaces with hydraulic oil.
3. Install seals and bearings in piston sleeve, piston, shaft,
and end cap. Lips of exclusion seals (16) face outward.
Lips of high pressure seals face inward.
4. Place actuator in a vertical position. Install piston sleeve
(3) in timed relation to the housing, applying firm pres-
sure as the new seals and bearings enter the housing
and become compressed by the housing chamber.
NOTE: Do not mis-align sleeve. It will mar cylinder bore. Timing
marks must be aligned for proper shaft orientation. Refer
to Figure 4-4., Timing Marks.
Figure 4-4. Timing Marks
5. If actuator is not equipped with grease fittings, coat
thrust bearings (20) with grease before sliding on shaft
and end cap.
6. Shaft is installed by aligning punched timing marks.
Temporarily taping threaded portion of shaft will help
installation past shaft seals (masking tape works well).
7. Apply anti-seize to threaded and surrounding areas of
end caps. End cap may need to be installed with actua-
tor in a vertical position.
8. End cap (5) is torqued to 60-400 ft-lb (84-560 Nm)
depending on actuator size, so actuator begins rotation
at approximately 100 psi (6.9 bar) pressure.
9. Shaft flange cannot be rotated by hand. Combined back
drive and friction prevent manual rotation.
10. If end cap is torqued too high, actuator may require as
much as 300 psi (20.7 bar) to rotate. If end cap is not
torqued high enough, shaft axial motion and radial
backlash will result. End cap must be secured against
shaft by tightening cap screws (7), or installing axial set-
screws, depending on model.
11. Apply hydraulic pressure and check for breakaway pres-
sure and shaft axial motion.
12. To test for leakage, pressurize Port P2 to 3000 psi (206.8
bar). No oil should seep from Port P1 or from end cap (5).
13. Repeat test by pressurizing Port P1 and check for leak-
age out of Port P2, around shaft flange (2B), and ring
gear pin welds.