SANY LATIN AMERICA
4-84
SY195/205/215/225C9 Crawler Hydraulic Excavator
Structure and Function
Shop Manual - June 2013
4.6.3 Relief valve portion
Structure
●
The relief valve portion consists of relief
valves (1) and (2), check valves (3) and (4).
Function
●
When the machine is in the swing holding
mode, control valve (5) closes the motor
outlet circuit, but the motor rotation contin-
ues due to inertial force. The motor output,
therefore, is abnormally increased, result-
ing in motor damage.
●
In order to avoid the motor damage, the
relief valve relieves the abnormally high
pressure to port (M) from the motor outlet
side (high-pressure side) of the motor.
NOTE: For the location of the relief valve on
the swing motor, see “Swing motor” on page 4-81.
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