JLG 450A_AJ Series II Service Manual - Manual (Page 106)

SECTION 3 - CHASSIS & TURNTABLE
3-56 – JLG Lift – 3121180
SHAFT
Inspect motor shaft. Look for damage or excessive wear
on output and block splines. Inspect bearing surfaces and
sealing surface. Replace shafts with damaged or exces-
sively worn splines, bearing surfaces, or sealing surfaces.
SERVO PISTON AND MINIMUM ANGLE STOP
Inspect minimum angle stop, servo piston head, and
servo piston ball-socket for damage or excessive wear.
Replace if necessary.
LOOP FLUSHING SPOOL
Inspect loop flushing spool. Check for cracks or damage.
Replace if necessary.
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 relax-
ation, compress seal by installing piston head in
servo cavity in end-cap and let it stand for at least
five minutes.
2. After piston seal has relaxed, lubricate and install
servo piston into housing bore. Align piston with ball
socket facing inside of housing.
COMPRESSED SPRING MAY FLY OUT AND CAUSE SERIOUS
INJURY. COMPRESSING BLOCK SPRING REQUIRES ABOUT 80 TO
90 LBF (350 TO 400 N) OF FORCE. USE A PRESS SUFFICIENT TO
MAINTAIN THIS FORCE WITH REASONABLE EFFORT. ENSURE
SPRING IS SECURE BEFORE ATTEMPTING TO INSTALL SPIRAL
RETAINING RING. RELEASE PRESSURE SLOWLY AFTER RETAINING
RING IS INSTALLED.
3
2
1
3
1. O-ring
2. Piston Seal
3. Servo Piston
Figure 3-36. Servo Piston