
Reference
Only
INTRODUCTION
18000 SERIVCE/MAINTENANCE MANUAL
1-64
Published 12-05-17, Control # 035-23
Jacking Cylinders
See Figures
Telescopic type jacking cylinders are mounted on each
corner of rotating bed. Jacking cylinder operation is
controlled with switches on hand-held radio remote control
and programming. Operation of all four jacking cylinders is
the same. The following description of operation is for a
single jacking cylinder.
The rotating bed level sensor keeps rotating bed level when
the ALL switch is used. The sensor controls fluid to each
cylinder by opening/closing proportional control valves.
Each jacking cylinder has a counterbalance valve at the
cylinder ports. Counterbalance valves ensure smooth control
when raising or lowering the crane. Counterbalance valves
lock the jacking cylinders in place if there is a hydraulic line
breakage or accidental operation of control valve when the
crane's power is shut down. Also, counterbalance valves
provide relief protection for the cylinders and shields them
from mechanical overloading.
When a jacking cylinder proportional control valves is not
enabled, it shifts to neutral position where both valve section
cylinder ports are connected to tank. This prevents inline
pressure from opening counterbalance valve, holding
rotating bed load in position by the counterbalance valve.
Rotating bed Jacking - Raise
Move desired jacking switch to extend position and hold. An
input voltage is sent to node-1 controller. Node-6 controller
sends a 24 volt output to enable selected jacking cylinder
proportional control valve (HS-20) and shifts valve to the
raise position. Node-5 controller sends a variable zero to 24
volt output voltage to enable accessory system proportional
relief valve.
Hydraulic fluid pressure at approximately 3,000 psi (204 bar)
flows to selected jacking cylinder(s) proportional control
valve. Hydraulic fluid exits valve and enters free-flow check
valve section of jacking cylinder counterbalance valve.
Hydraulic fluid then enters piston end of jacking cylinder,
extending cylinder to raise the rotating bed. Node-4
controller monitors accessory system pressure sender to
control jacking cylinder raising speed rate.
Hydraulic fluid returning to tank from rod end of the jacking
cylinder is blocked by the free-flow check valve section of
counterbalance valve and flows through flow restraining
section that has a relief setting of 2,500 psi (172 bar). The
counterbalance valve acts as a deceleration control and
functions with a 3:1 pilot ratio of the relief pressure. This
permits the valve to open when the pressure in rod end of the
cylinder is approximately 833 psi (57 bar). Restraining
section of counterbalance valve opens, controlling the fluid
out of the jacking cylinder. Hydraulic fluid then flows through
free-flow check valve section of flow control valve before
entering lower accessory valve. Hydraulic fluid leaving the
lower accessory valve is returned to tank.
When rotating bed switch is moved back to center position,
node-4 controller sends a zero output voltage to shift spool of
rotating bed solenoid valve HS-20 to center position.
WARNING
Collapsing Hazard!
Keep rotating bed as level as possible while jacking.
Operating jacking cylinder with rotating bed more than
three degrees out of level can cause structural damage to
jacking cylinders and possible collapse of rotating bed.
Содержание 18000
Страница 1: ...R e f e r e n c e O n l y Service Maintenance Manual Manitowoc 18000 ...
Страница 2: ...R e f e r e n c e O n l y ...
Страница 4: ...R e f e r e n c e O n l y THE ORIGINAL LANGUAGE OF THIS PUBLICATION IS ENGLISH ...
Страница 210: ...R e f e r e n c e O n l y NOTES SKETCHES AND PHOTOGRAPHS ...
Страница 315: ...R e f e r e n c e O n l y ...
Страница 316: ...R e f e r e n c e O n l y ...