JLG 680S, Service And Maintenance Manual, Page: 119 / 530

SECTION 3 - CHASSIS & TURNTABLE
3121234 3-67
SHAFT BEARINGS
Inspect bearings for excessive wear or contamination. Rotate
the bearings while feeling for uneven movement. Bearings
should spin smoothly and freely. Replace bearings that appear
worn or do not rotate smoothly.
SHAFT
Inspect the motor shaft. Look for damage or excessive wear on
the output and block splines. Inspect the bearing surfaces and
sealing surface. Replace shafts with damaged or excessively
worn splines, bearing surfaces, or sealing surfaces.
SERVO PISTON AND MINIMUM ANGLE STOP
Inspect the minimum angle stop, servo piston head and servo
piston ball-socket for damage or excessive wear. Replace if
necessary.
LOOP FLUSHING SPOOL
Inspect the loop flushing spool. Check for cracks or damage.
Replace if necessary.
Assembly
1. Install new o-ring (1) and piston seal (2) to the servo pis-
ton (3). Install the piston seal over the o-ring.
NOTE: Installing the piston seal stretches it, making it difficult to
install the servo piston in its bore. Allow 30 minutes for the
seal to relax after installation. To speed up seal relaxation,
compress the seal by installing the piston head into the
servo cavity in the end-cap and let it stand for at least five
minutes.
2. After piston seal has relaxed, lubricate and install servo
piston into the housing bore. Align the piston with the
ball socket facing the inside of the housing.
3
2
1
3
1. O-ring
2. Piston Seal
3. Servo Piston
Figure 3-48. Servo Piston