SANY LATIN AMERICA
4-58
SY195/205/215/225C9 Crawler Hydraulic Excavator
Structure and Function
Shop Manual - June 2013
[Pilot circuit]
●
When the bucket spool (304) is switched,
the side path is closed and pressure at port
Px (work equipment signal port) rises. At
the same time, pressure oil is supplied at
port XBp2.
[Main circuit]
●
When bucket DUMP is operated, pilot
pressure oil is supplied into port XBk and
bucket spool (304) moves to the left. Work-
ing oil from port P1 is introduced into neu-
tral bypass (2) via main passage (1). Neu-
tral bypass is cut off by switching bucket
spool (304). Therefore, working oil in the
parallel passage pushes open the cone
valve (511) of the check valve, and flows
into the bucket spool (304) via the U pas-
sage. Then, it flows into the periphery of
bucket spool (304) and is supplied into the
bucket cylinder rod end (R) via port Bk.
●
On the other hand, return oil from the buck-
et cylinder head end (H) flows in via port
Ak. Then, it flows to oil tank port (R1) via
the spool periphery and returns to working
oil tank.
●
When bucket DIG is operated, pilot pres-
sure oil is supplied into port XBp2 and the
neutral bypass cutoff valve spool (310) is
switched. Working oil from port P2 is in-
troduced into neutral bypass (2) via main
passage (3). Neutral bypass is cut off by
switching neutral bypass valve spool (310).
Therefore, working oil pushes open the
check valve, and interconnects with the U
passage via the inside path, and converg-
es with bucket spool (304).
(2) Bucket DUMP
(3) Bucket confl uence
H
R
Ak
Bk
XBk
ZX225-1102019
https://www.tractormanualpdf.info/