SANY LATIN AMERICA
4-85
SY195/205/215/225C9 Crawler Hydraulic Excavator
Structure and Function
Shop Manual - June 2013
Operation
1. When swing begins (suppose pressur-
ized oil enters Port A)
●
When the swing control lever is operated
for right swing, pressurized oil from the
pump is supplied to port (A) via control
valve (5).
●
The pressure on port (A) rises, the starting
torque is generated in the motor, and the
motor is activated.
●
The pressurized oil from the outlet port of
the motor passes from port (B) through the
control valve (5) and returns to the tank.
2. When swing stops
●
When the swing control lever is neutral-
ized, the supply of pressurized oil from the
pump to port (A) is cut off.
●
The pressurized oil from the motor outlet
can't return to the tank since the return cir-
cuit to the tank is closed from control valve
(5). Thus, pressure at port (B) rises.
●
Swing resistance is generated on the mo-
tor and hence the brake starts working.
●
Pressurized oil will be relieved when the
pressure on port (B) rises to the set pres-
sure of relief valve (2).
●
A high braking torque is applied on the mo-
tor, thereby stopping the motor.
●
When relief valve (2) is being actuated, the
relieved pressurized oil and the pressur-
ized oil from port (M) are fed to port (B) via
check valve (4).
●
Above prevents cavitation on port (B).
ZX215-1002085
1
2
3
C
A
B
5
4
From port M
ZX215-1002086
1
2
3
C
5
4
A
B
From port M
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