JLG 450AJ Service Manual - Manual (Page 32)

SECTION 2 - PROCEDURES
2-16 – JLG Lift – 3120869
IF THE CYLINDER IS TO BE TESTED PRIOR TO INSTALLATION ON
THE MACHINE, EXTREME CARE SHOULD BE USED TO INSURE
THAT THE OUTER END OF THE ROD IS SUPPORTED. USE
EITHER A TRAVELING OVERHEAD HOIST, FORK-LIFT, OR OTHER
MEANS TO SUPPORT THE OVERHANGING WEIGHT OF THE
EXTENDING ROD.
2.10 MID AND LOWER LIFT CYLINDER
BLEEDING PROCEDURE
NOTE: Bleeding procedure should only be necessary if
rebuilding or replacing lift cylinder.
1. Check oil level in the hydraulic oil tank (all booms
must be retracted). Lay an oil drip pan under the rod
end port block (Mid Cylinder) and crack bleeder
open from the fitting in the port block.
2. From the platform, turn the speed control knob to
the slow position.
3. Lift up very slowly. This will force any air out of the
circuit. If the lower boom is not extending, turn the
speed control up very slowly until the lower boom
starts to move.
4. Raise the lower boom approx. 30.5 cm (1 foot), then
close bleeder while the boom is still moving.
5. Lift down all the way.
6. Repeat this procedure until all air has been purged
from the circuit. Re-check the hydraulic oil level.
7. To test, cycle the lower lift function 3-4 times to see if
both cylinders stop at the same time when fully
extended.
2.11 HYDRAULIC PUMP (GEAR)
Disassembly
NOTE: The following general instructions also apply to multi-
ple section gear pumps, the only extra parts are the
coupling between the drive shafts and the center dis-
tance plate which divides the two pump sections.
This repair procedure also applies to the "W" series
Gear Motors.
1. It is very important to work in a clean work area
when repairing hydraulic products. Plug ports and
wash exterior of pump with a proper cleaning sol-
vent before continuing.
Table 2-1.Cylinder Head and Tapered Bushing Torque
Specifications
Description
Head Torque Value
(Wet)
Tapered Bushing
Torque Value (Wet)
Upper Lift Cylinder 50 ft. lbs.
(68 Nm)
9 ft. lbs
(12 Nm)
Upper Lift Cylinder (AJ) 80 ft. lbs.
(109 Nm)
9 ft. lbs
(12 Nm)
Mid Cylinder
80 ft. lbs.
(109 Nm)
9 ft. lbs
(12 Nm)
Lower Cylinder N/A
9 ft. lbs
(12 Nm)
E.A.R. Cylinder
30 ft. lbs
(41 Nm)
5 ft. lbs.
(9 Nm)
Tele Cylinder N/A
5 ft. lbs.
(9 Nm)
Level Cylinder
80 ft. lbs.
(109 Nm)
5 ft. lbs.
(9 Nm)
Axle Oscillation
Cylinder
30 ft. lbs.
(41 Nm)
N/A
Steer Cylinder
30 ft. lbs.
(41 Nm)
N/A
Table 2-2.Holding Valve Torque Specification
Description Torque Value
SUN - 7/8 HEX M20 x 1.5 THDS. 30-35 ft.lbs.
(41-48 Nm)
SUN - 1 1/8 HEX 1-14 UNS THDS.
45-50 ft.lbs.
(61-68 Nm)
SUN - 1 1/4 HEX M36 x 2 THDS.
150-160 ft.lbs.
(204-217 Nm)
RACINE - 1 1/8 HEX 1 1/16-12 THDS.
50-55 ft.lbs.
(68-75 Nm)
RACINE - 1 3/8 HEX 1 3/16-12 THDS.
75-80 ft.lbs.
(102-109 Nm)
RACINE - 1 7/8 HEX 1 5/8-12 THDS.
100-110 ft.lbs.
(136-149 Nm)