11 - 1
Hose Burst Protection Valve
Boom & Dipper Operation
The small letter annotations A, B, X, and Y are stamped on
the valve.
Operation 1 - Load Raise
When 'dipper out' is selected, oil from the excavator valve
block is fed to port B, the oil opens check valve C against
spring D and passes through internal galleries into the rod
(raise) side of the ram via port Y.
Oil from the head side of the ram enters at port X, opens
check valve assembly E and returns to tank via port A and
the excavator valve block.
Operation 2 - Load Lower
Oil from the excavator valve block is fed to port A. The
connection to the head side of the ram is blocked by the
check valve assembly E and the position of spool F.
A cross drilling G in the valve connects the A port gallery to
cavity J. The pressure in cavity J increases to such a point
that it moves spool F to the left against the force of spring H.
The new position of the spool creates a connection between
the A port gallery and the head side of the dipper ram (via
port X).
There is also a connection between the Y port gallery and
the B port gallery. Oil from the rod side of the ram enters at
port Y and returns to tank via port B and the excavator valve
block.
Component Key:
C Check Valve
D Spring
E Check Valve Assembly
F Spool
G Cross Drilling
H Spring
J Cavity
Section E
Hydraulics
9803/3280
Section E
11 - 1
Issue 1
Circuit Descriptions
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