31 - 5
Section E
Hydraulics
9803/6400
Section E
31 - 5
Issue 2*
Control Valve JS200/JS240
Operation (continued)
Bucket Spool Selection
Dump: Crowd (Refer to Fig. 11).
When the pilot port P
bR3 (PaR3) is pressurised and the bucket I spool is selected, the 4-spool neutral passage a is cut off and
the oil delivered from PR flows through the 4-spool parallel passage b, pushes up the load check valve (v) and from the passage
n flows through the spool neck and from passage P (q) flows to the cylinder port B
R3 (AR3).
The return oil from the cylinder port A
R3 (BR3) flows through the spool neck from passage q (P) and is released to the tank
passage.
II Speed Confluence (Refer to Fig. 11, 12).
When the bucket I spool is selected, (Dump: Crowd: Fig. 11), when pilot port P
aR4 is pressurised and bucket II is selected (Fig.
12), the oil delivered from P
L flows into passage Y w from the 5-spool neutral passage A and arm I spool land, flows through the
bucket II spool hole (u), pushes up the poppet (t) and converges in bucket I passage n from passage o (Fig. 1).
Slew Spool Switch (Refer to Fig. 11).
When the pilot port P
bL3 (PaL3) is pressurised and the spool is selected, the 5-spool neutral passage A is cut off and the oil
delivered from P
L
port flows through the 5-spool parallel passage B and pushes open the load check valve (s) and flows
through the spool neck from passage P and flows from passage R (Q) to cylinder port BL3 (AL3).
The return oil from cylinder port A
L3 (BL3) flows through the spool neck and is released to the tank.
Spare Spool Switch (Refer to Fig. 5).
When the pilot port P
bL2 (PaL2) is pressurised and the spool is switched, the 5-spool neutral passage A is cut off and the oil
delivered from the P
L port flows through the 5-spool parallel passage B and pushes up the load check (r). From passage M, it
flows through the spool neck, through the passage o and flows to cylinder port B
L2 (AL2). Also, the oil delivered from the outside
to the P
5 port flows through the load check valve (r) passage (q) and converges in passage M.
The return oil from cylinder port A
L2 (BL2
) flows through the spool neck and is returned to the tank.
Travel Linearity Spool (Refer to Fig. 18).
When an excavator spool is selected, the signal passage is cut off, but when the travel spool is in neutral, the signal oil is
released to the tank at the travel spool signal land (K) (L) so the pressure of the signal passage (f) does not rise and the travel
linearity spool is in the neutral condition. (Fig. 1)
(When the boom is raised, it is selected to boom II. Fig. 8)
Also, when the spool at the front is switched, the flow to the tank passage of the signal passage (e) is cut off so the P
f port
pressure rises.
(For travel linearity spool selection conditions, refer to the next item, ‘Travel Combination Operations’).
*
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