11 - 5
Hose Burst Protection Valve
Loader Operation
The small letter annotations
V2
,
C2, P
,
T
and
E
are the same
as the port markings found on the HBPV.
Operation 1 - Load Raise
When lift is selected, oil from the loader valve block
9
is fed
to port
V2
on the HBPV, the oil opens check valve sleeve
A
against spring
B
and passes through internal galleries into
the (raise) side of the ram via port
C2
.
Oil from the lower side of the ram returns to tank via port
P
and the loader valve block.
Operation 2 - Load Lower
Oil from the loader valve block
9
is fed directly to the (lower)
side of the ram. A pilot line
C
from the service line is
connected to the HBPV at port
P
.
Oil enters the HBPV at port
P
and passes through drilling
D
,
down threads
F
and acts on the end face of piston
G
. The
pressure is sufficient to move piston
G
to the right, thus
moving plunger
J
off its seat against spring
H
. With the
plunger off its seat, oil from the opposite side of the ram
enters the HBPV at port
C2
, passes through the HBPV and
returns to tank via port
V2
and the valve block.
A drilled hole
N
through the centre of plunger
J
connects
chamber
Q
to atmosphere
T
, this prevents the pressure in
chamber
Q
from rising to such a point that it would prevent
any movement of plunger
J
.
Threads
F
and the one-way check valve ball
L
act as
restrictors to 'dampen' any adverse effects of operating the
control levers erratically.
Section E
9803/3280
Section E
11 - 5
Issue 1
Circuit Descriptions
Component Key:
A
Check Valve Sleeve
B
Spring
C
Pilot Line
D
Drilling
F
Thread
G
Piston
H
Spring
J
Plunger
L
Ball
N
Orifice
Q
Chamber
9
Loader Valve Block
22
E
C2
P
T
V2
9
A
B
A323090
22
J
C2
P
T
V2
9
G
C
D
H
L
A323091