31 - 14
Operation (cont’d)
Combination Operation
1. Travel Combination Operation (Refer to Fig. 12,).
The signal passage and tank passage are cut off when the
spool signal land and the signal passage pressure rises to
the relief set pressure in the following situations:
When travelling forward or backward (including spin
turn).
When any spool other than the travel spool is selected.
When operating the excavator.
When the travel spool (left, right travel) is selected.
In this straight travel state, the oil delivered from port 4P
passes through neutral passage (a) activates the travel right
spool, pushes up the poppet (28), flows into the shuttle
travel straight spool neck (8) flows into the passage (14) to
the 5-spool travel left spool.
In this way, the left and right traction motors are activated so
straight travel can be maintained while simultaneous actions
with other services are carried out.
Part of the oil from port 5P passes through the parallel
passage (B), the restrictor (29) and the load check valve (9).
This feeds the travel section, decreasing the travelling speed
and reducing shock while switching the travel straight spool
(8).
Section E
Hydraulics
9803/6020
Section E
31 - 14
Issue 1
Control Valve
289850
Fig. 12
A
B
C
D
A
Travel (Left)
B
Travel (Right)
C
5-Spool Parallel Passage
D
4-Spool Neutral Passage
Summary of Contents for JS70
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