Daewoo Solar 225LC-V, Shop Manual

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S0707200
Page 5
Swing Motor
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RELIEF VALVE
The relief valve is one in a set of two, and is
Item "51" of the swing motor assembly.
Return line pressure (the normal pressurization
of the hydraulic reservoir, also referred to as
"tank pressure") pushes the valve piston to open
ports "R" and "P" at the end of the valve
whenever the hydraulic system is operating.
This valve initially reacts to the engagement of
hydraulic function (and pressurization of the
tank) by opening momentarily, so that there is
no pressure developed through the valve at all.
Tank pressure at "pressurized area A2" is set
against spring pressure inside the valve,
opening the relief valve until pressure at the
spring chamber ("g") momentarily reduces "g"
chamber pressure "Pg." "Pg" subsequently
increases until the piston reaches the end of
travel inside the valve bore at "h."
After the piston reaches "h" and its normally
closed, pressurized operating position, pressure
through the valve can be continually increased
up to the relief valve maximum pressure ("Ps").
Where Fsp: Spring Force
SWING BRAKE OPERATION
The swing brake is normally held in the applied position - preventing the upper deck revolving
superstructure from rotating - whenever the hydraulic system is not operated (pressurized). The brake
system is automatically released whenever the swing controls are engaged to swing in one direction or the
other.
Figure 2
Ps
Fsp
A
1
A
2
–
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