SANY LATIN AMERICA
4-97
SY195/205/215/225C9 Crawler Hydraulic Excavator
Structure and Function
Shop Manual - June 2013
●
When hydraulic oil from the main pump
enters port P1 of the counterbalance valve,
spring (3) is pushed to the left by check
valve (2-1), opening circuit C1. The hy-
draulic oil enters the piston motor via port
M, trying to make the motor rotating. At the
same time, return oil from the piston motor
enters the counterbalance via port M2, but
it is stopped by check valve (2-2). The out-
put pressure of the main pump increases
as a result, and the hydraulic oil works
on the inside of spring chamber (1) and
damper chamber (A1) via ori
fi
ce (4-1) and
check valve (5-1). The force generated in
this way pushes spring (7-2) on the other
side and moves piston (1) to the right. At
this time, return oil from port M2 passes
through circuit of the notch on the periph-
ery of piston (1), and through port P2 when
pressure is generated at port M2, and en-
ters the tank via the main valve
fi
nally. The
motor is activated at this time.
ZX215-1002095
6-2
7-2
5-2
4-2
2-2
2-1
4-1
5-1
7-1
6-1
8-2
8
8-1
3
1
M1
P1
P2
M2
Circuit B
Circuit C2
Damper chamber A2
Orifice D4
Spring chamber 2
Circuit C1
Orifice D1
Damper chamber A1
Orifice D2
Spring chamber 1
Orifice D3
B. When the motor is activated
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