Service Manual Instruction Manual

SECTION 3 - CHASSIS & TURNTABLE
3-24 – JLG Lift – 3121616
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 the 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 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.
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,
compress seal by installing piston head in 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 in housing bore. Align piston with ball socket fac-
ing inside of housing.
RISK OF PERSONAL INJURY: COMPRESSING BLOCK SPRING REQUIRES ABOUT
80 TO 90 LBF (350 TO 400 N) OF FORCE. USE A PRESS SUFFICIENT TO MAIN-
TAIN THIS FORCE WITH REASONABLE EFFORT. ENSURE SPRING IS SECURE
BEFORE ATTEMPTING TO INSTALL SPIRAL RETAINING RING. RELEASE PRES-
SURE SLOWLY AFTER RETAINING RING IS INSTALLED.
3
2
1
3
1. O-ring
2. Piston Seal
3. Servo Piston
Figure 3-28. Servo Piston