SANY LATIN AMERICA
4-62
SY195/205/215/225C9 Crawler Hydraulic Excavator
Structure and Function
Shop Manual - June 2013
4.5.2.8 Travel straight
When travel spool (301) and other spool are
operated simultaneously.
The following case shows when travel spool
(301) and swing spool (305) are operated si-
multaneously. (When pilot pressure oil is sup-
plied to port XAtL, port XAtr and port Xas)
[Pilot circuit]
●
The side path of right/left travel spool (301)
and the side path of the swing spool (305)
at the down
fl
ow side are closed.
●
Pilot oil from port PG is supplied to port
PTa and straight travel spool (308) is
switched.
[Main circuit]
●
When straight travel spool (308) is
switched, the right/left travel spool (301)
are interconnected with port P2. The paral-
lel passage of swing/boom 2/option/arm
1 circuit and boom 1/bucket/arm 2 circuit
are interconnected with port P1. Therefore,
working oil supplied from port P2
fl
ows into
port Atl and port Atr, and is supplied to the
two travel motors equally.
●
On the other hand, working oil from port P1
is supplied to the swing motor via port As.
●
When oil pressure at port P2 is lower than
that at port P1, part of the working oil form
port P1 is supplied to port P2. In this way,
sharp decrease of travel speed is averted.
P1
P2
PTa
ZX225-1102023
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