HYDRAULIC SYSTEM 5540F/YB5515 SERVICE MANUAL
4-34 Published 10-21-2010, Control# 198-04
OUTRIGGER CIRCUIT
General
Two outrigger hydraulic systems are available on the crane:
• Standard outrigger controls.
• Optional independently controlled outriggers.
Standard Outrigger Hydraulic System
The standard outrigger hydraulic system (Figure 4-36)
includes the four outriggers cylinders with holding valves,
two sections of the main control valve and the hydraulic
lines.
Optional Independently Controlled Outrigger
Hydraulic System
The optional independently controlled outrigger hydraulic
system (Figure 4-37) includes the four outrigger cylinders
with holding valves, four sections of the main control valve
and the hydraulic lines.
Oil Flow
Outrigger Down
Pushing the handle (pushing the valve spool IN), routes oil
out of the valve port A (Figure 4-38 and Figure 4-39) to the
base end of the hydraulic cylinder.
In the down direction, oil flows freely through the holding
valve and into the base end of the cylinder. The cylinder
extends and pushes oil ahead of the piston through the rod
end port of the cylinder. The oil returns to port B of the control
valve. From here, the oil is routed into the tank passage and
returns through the main filter to the hydraulic tank.
Outrigger In
Pulling the handle (pulling the valve spool OUT), routes oil
out of the valve port B (Figure 4-38 and Figure 4-39) to the
rod end of the hydraulic cylinder. The cylinder starts to retract
but meets resistance from the oil held in the cylinder base
end by the holding valve. this restriction causes an increase
in pressure as the pump continues to push more oil into the
rod port of the cylinder. When the pressure is high enough to
open the holding valve, the cylinder retracts. See Load
Holding Valve. Oil from the rod end of the cylinder returns to
port A of the control valve. From here, the oil is routed into
the tank passage and returns through the main filer to the
hydraulic tank.
Reference Only
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