Unloading Relief Valve0 pages

Pub. EC-0205

UNLOADING RELIEF VALVES
BUCG-06/10 (3/4, 1-1/4)
Sub-plate Mounting

PRESSURE
CONTROLS

Specifications / Model Number Designation
Up to 21 MPa (3050 PSI), 250 L /min (66 U.S.GPM)

C

These valves are used to operate the pumps with minimum load in
accumulator circuits or in high-low pump circuits.
In accumulator circuits, when the system pressure reaches to a cut out
pressure (adjusted maximum), the valve acts to divert the pump delivery to
the reservoir at low pressure, thus the pump is unloaded automatically.
When the accumulator pressure drops to the cut in pressure (refer to
characteristic chart on page 5), the valve directs the pump delivery to the
accumulator and hydraulic system.
An integral check valve prevents reverse flow through the valve from the
accumulator.
In high-low pump circuits, the valve acts to unload the large volume pump
with the same manner as described above during load operation of the small
volume pump.

Specifications
Model Numbers

Max.
Operating Pres.
MPa (PSI)

Max. Flow
L /min
(U.S.GPM)

Approx. Mass

125
(33)

12
(26.5)

250
(66)

21.5
(47.4)

BUCG-06-∗∗-30/3080/3090
21 (3050)
BUCG-10-∗∗-25/2580/2590

kg(1bs.)

Graphic Symbol

Model Number Designation

FSpecial Seals
F:
Special Seals
for Phosphate Ester
Type Fluids
(Omit if not
required)

BUC
Series Number

BUC:
Unloading
Relief Valve

G
Type of
Mounting

G:
Sub-plate
Mounting

-06

-B

V

-30

∗

Valve
Size

Cut-out Pres.
Adj. Range
MPa (PSI)

High Venting
Pres. Feature

Design
Number

Design Standards

06

B: 2.5-7.0
(360-1020)
C: 3.5-14
(510-2030)

10

H: 7.0-21
(1020-3050)

V:
For High
Venting
Pressure
Feature
(Omit if not
required)

30

25

None:
Japanese
Std. "JIS"
80: European
Design Std.
90: N. American
Design Std.

Use the high-venting-pressure type to reduce the shift time from unloading to onloading.

No.1