jcb JS200 Service Manual page 272

Section E
31 - 4
Operation (continued)
* Dipper Spool Selection
1. Dump (Refer to Fig. 9).
* When the pilot port P
aL4
passage A pushes up the sleeve (S) load check valve (T) and, through passage U, passes through the spool neck and passage
V, pushing open the load sensing valve poppet (U) and flowing from the cylinder port A
Also, part of the oil delivered by P
valve (W) and converges in passage U.
The return oil from cylinder port B
2. Crowd (Refer to Fig. 10, 15, 16).
When the pilot port P
bl4
neutral passage A pushes up the sleeve (S) load check valve (T) and from passage U flows through spool neck and passage X
and flows from the cylinder port B
passage b, pushes open the load check valve (W) and converges in passage U.
*
The return oil from cylinder port A
the tank passage, but at this time, part of the oil flows through the spool hole (X), pushes open the regenerative circuit poppet
(Y) inside the spool, flows through the restriction (Z) and converges in the passage U (Fig. 15,16).
3. II Speed Confluence
*
When the dipper I spool is selected (Dump, Crowd: Fig. 9, 10), when the pilot port P
switched, the oil delivered from P
converges into passage U from passage t or Z and at the same time pushes open the check valve (y) poppet (x) (Fig. 3). It
flows through the outer passage from the P6 port, through passage v from A
and converges in passage u.
9803/6400
Control Valve JS200/JS240
is pressurised and the arm I spool is selected, the oil delivered from P
flows from 5-spool parallel passage B to the restriction (V), pushes open the load check
L
flows through the spool neck from passage X and is released to the tank passage.
L4
is pressurised and dipper I spool is selected (Fig. 10), the oil delivered from P
. Also, part of the oil delivered from P
L4
pushes open the load sensing valve poppet (U), flows through passage V and is released to
L4
port flows through 4-spool neutral passage a and pushes open load check valve (z) and
R
Hydraulics
flows through the restriction from the 5-spool parallel
L
port and flows through the spool restriction (w)
R4
port through the 5-spool neutral
L
.
L4
through the 5-spool
L
is pressurised and dipper II spool is
bR4
Section E
31 - 4
Issue 2*