SANY LATIN AMERICA
4-98
SY195/205/215/225C9 Crawler Hydraulic Excavator
Structure and Function
Shop Manual - June 2013
●
When the engine runs at an excessively
high speed because of external force ap-
plied on it, the motor may lose control. At
this time, port P1 serves as the inlet side,
and the pressure drops. Pressure in spring
chamber 1 and damper chamber A1 also
drop. As a result, pison (1) moves to the
left under the force of spring (7-2), closing
circuit B. Circuit at the suction side is also
closed at the same time when the circuit
at return side is closed. When circuit B is
closed, pressure at port P1 rises due to
hydraulic oil from the main pump, moving
piston (10 to the right again. In this way,
when external load generates pump effect,
slight movement of piston (1) keep circuit
B open. The rotation speed of the motor
keeps in line with fuel supply of the main
pump, and the motor will not lose control
because of the vacuum in the hydraulic
system.
C. Counterbalance function
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