DH6/10

Logic valve
Logic valve
KLD/LU
A port pressure
B port pressure
External pilot
pressure cover
Cover
Spring
Sleeve
Valve body
Structure and operation of logic elements
Without cushion overlap With cushion overlap
Structure
Logic elements consists of, as shown in the
figure, a sleeve with internal seat, valve body,
spring that always holds the valve body, and
control ports, and the cover on which various
types of valves and stroke limitters are to be
installed.
There are two types of valve body, with and
without cushion overlap, each of which can be
used for different usage. Though the valve body
with the cushion overlap has higher flow
resistance, it is used as a flow rate control valve
in combination with a stroke limitter, or in order
to tame switching shock under high pressure.
Operation
The hydraulic oil can flow in both direction of
A B and B A, and open and close of the
valve body are determined by the pressure in
the pilot room. Hence, the pilot pressure is led
internally or externally and controlled.
Supposing that there is no pressure applied in
the pilot room, the valve openes when the
hydraulic force of A or B port becomes higher
than the spring force, and if pressure is applied,
the valve opens when the pressure of A or B
port increases by the corresponding area ratio.
The three areas shown in the figure
significantly affect the functions. Assuming that
the area A1 is 100%, the ring shape area A2 is,
depending on the type, 7% or 50%. Hence the
area ratio A1:A2 is 14.3:1, or 2:1 respectively,
and the area A3 which is computed by (A1 +
A2) becomes 107% or 150% of A1 respectively.
The area A3 is determined by each nominal
dimension and common to the types, while A1
varies depending on the type. Cracking
pressure for spring type 40 logic element KLD
-10-
40, if there is no pilot pressure applied,
is shown in the table depending on the type.
Logic element type
Area ratioA1A2
Cracking pressure A port side
MPakgf/cm 2 B port side
Specifications
As shown avobe, selecting each cartridge
assembly in combination with various
cover for the usage allows a large variety
of controls.
16 25 32 40 50 63 80 100
Nominal dimension
Poppet area A3cm 2
Maximum working Port Solenoid operated directional valve
pressure
ABX 30.9 MPaFor 315 kgf/cm2with cover
MPakgf/cm 2 Z1Z2
Other covers
Sheet area A1cm 2
Ring shape area A2cm 2
Poppet strokemm
Stroke volumecm 3
Area ratio 21
Area ratio 14.31
Area ratio 21
Area ratio 14.31
With cushion overlap
Without cushion overlap
With cushion overlap
Without cushion overlap
Masskg
Cartridge assembly
Standard cover
Accessories
Mounting bolt
Type
Size Cover type
All types
Hexagon socket
head cap thread
Quantity
4 pcs.
All types 4 pcs.
All types 4 pcs.
4 pcs.
All types other than above 4 pcs.
4 pcs.
All types other than above 4 pcs.
4 pcs.
All types other than above 4 pcs.
8 pcs.
All types other than above 8 pcs.
8 pcs.
All types other than above 8 pcs.
Tightening torque Nm (kgfcm)
5-2