JLG 500RTS ANSI Service Manual - Manual (Page 21)

SECTION 2 - PROCEDURES
3121103 – JLG Sizzor – 2-5
2. Raise platform completely and place a suitable over-
head lifting device or prop approximately 1 in. (2.5
cm) below the platform.
NOTE: Step (3) applies to the leveling jacks only.
3. Fully extend leveling jacks to check.
4. Shut down hydraulic system and allow machine to
sit for 10-15 minutes. Carefully remove hydraulic
hoses from cylinder port block.
5. There will be initial weeping of hydraulic fluid, which
can be caught in a suitable container. After the initial
discharge, there should not be any further leakage
from the ports. If leakage continues at a rate of 6-8
drops per minute or more, cylinder repairs must be
made. If the retract port is leaking, the piston seals
are defective and must be replaced. If the extend
port is leaking, the counterbalance valve is defective
and must be replaced.
6. If no repairs are necessary or when repairs have
been made, carefully reconnect hydraulic hoses to
the appropriate ports.
7. Remove lifting device from platform, activate hydrau-
lic system and run cylinder through one complete
cycle to check for leaks.
2.10 CYLINDER REMOVAL AND
INSTALLATION
Lift Cylinder Removal
1. Place the machine on a flat and level surface. Start
the engine/motor and raise the platform. Shut down
the engine/motor and attach a suitable support
device to the platform.
2. Remove the locknut, bolts, flatwashers and keeper
shaft securing the cylinder rod attach pin to the
upper inner arm assembly. Using a suitable brass
drift, drive out the rod end attach pin from the arm
assembly.
3. Retract the lift cylinder rod completely.
4. Tag and disconnect, then cap the lift cylinder
hydraulic lines and ports.
5. Remove the bolts, lockwashers, and flatwashers
securing the barrel end attach pin to the lower arm
assembly. Using a suitable brass drift, drive out the
barrel end attach pin from the arm assembly.
6. Carefully remove the cylinder from the Sizzor lift and
place in a suitable work area.
Lift Cylinder Installation
1. Install lift cylinder in place using suitable slings or
supports, aligning barrel end attach pin mounting
holes on lower arm assembly.
2. Using a suitable drift, drive the barrel end attach pin
through the mounting holes in the lift cylinder and
the lower arm assembly. Secure in place with the
bolts, flatwashers, and lockwashers.
3. Remove cylinder port plugs and hydraulic line caps
and correctly attach lines to cylinder ports.
4. Extend the cylinder rod until the attach pin hole
aligns with those in the upper arm assembly. Using a
suitable drift, drive the cylinder rod attach pin
through the aligned holes. Secure the pin in place
with the bolts, lockwashers, and flatwashers.
5. Lower platform to stowed position and shut down
motor/engine. Check hydraulic fluid level and adjust
accordingly.
2.11 CYLINDER REPAIR
NOTE: The following are general procedures that apply to
all of the cylinders on this machine. Procedures that
apply to a specific cylinder will be so noted.
Disassembly
DISASSEMBLY OF THE CYLINDER SHOULD BE PERFORMED ON
A CLEAN WORK SURFACE IN A DIRT FREE WORK AREA.
1. Connect a suitable auxiliary hydraulic power source
to the cylinder port block fitting.
DO NOT FULLY EXTEND CYLINDER TO THE END OF STROKE.
RETRACT CYLINDER SLIGHTLY TO AVOID TRAPPING PRES-
SURE.
2. Operate the hydraulic power source and extend the
cylinder. Shut down and disconnect the power
source. Adequately support the cylinder rod, if appli-
cable.
CYLINDERS WITH DOUBLE HOLDING VALVES. BEFORE REMOV-
ING HOLDING VALVES CRACK BLEEDER TO RELEASE PRES-
SURE.
3. If applicable, remove the cartridge-type holding
valve and fittings from the cylinder port block. Dis-
card o-rings.