JLG 660SJ Service Manual - Manual (Page 71)

SECTION 3 - CHASSIS & TURNTABLE
3121298 – JLG Lift – 3-27
SHAFT BEARINGS
Inspect bearings for excessive wear or contamination. Rotate
bearings while feeling for uneven movement. Bearings should
spin smoothly and freely. Replace bearings that appear worn
or do not rotate smoothly.
SHAFT
Inspect motor shaft for damage or excessive wear on output
and block splines. Inspect bearing surfaces and sealing sur-
face. Replace shafts with damaged or excessively worn splines,
bearing surfaces, or sealing surfaces.
SERVO PISTON AND MINIMUM ANGLE STOP
Inspect minimum angle stop, servo piston head, and servo pis-
ton ball-socket for damage or excessive wear. Replace as
required.
LOOP FLUSHING SPOOL
Inspect loop flushing spool for cracks or damage. Replace as
required.
Assembly
1. Install new O-ring (1) and piston seal (2) to servo piston
(3). Install piston seal over O-ring.
NOTE: Installing piston seal stretches it, making it difficult to
install servo piston in its bore. Allow 30 minutes for seal to
relax after installation. To speed up seal relaxation, com-
press seal by installing piston head in end-cap servo cavity
and let it stand for at least five minutes.
Figure 3-33. Servo Piston
2. After piston seal has relaxed, lubricate and install servo
piston in housing bore. Align piston with ball socket fac-
ing inside of housing.
1. O-ring
2. Piston Seal
3. Servo Piston
2
1
3
3