SANY LATIN AMERICA
4-2
SY195/205/215/225C9 Crawler Hydraulic Excavator
Structure and Function
Shop Manual - June 2013
4.5.2 Operating principle ....................................................................................... 4-48
4.5.2.1 When spool is in neutral position ........................................................ 4-48
4.5.2.2 Travel .................................................................................................. 4-50
4.5.2.3 Arm ...................................................................................................... 4-51
4.5.2.4 Boom ................................................................................................... 4-56
4.5.2.5 Bucket ................................................................................................. 4-59
4.5.2.6 Swing .................................................................................................. 4-61
4.5.2.7 Option ................................................................................................. 4-63
4.5.2.8 Travel straight ..................................................................................... 4-64
4.5.2.9 Lock valve function ............................................................................. 4-65
4.5.2.10 Main relief valve function .................................................................. 4-67
4.5.2.11 Port relief valve function .................................................................... 4-68
4.5.3 Section view ................................................................................................. 4-72
4.6 Hydraulic System, Part 3 ....................................................................................... 4-83
4.6.1 Swing motor ................................................................................................. 4-83
4.6.2 Swing holding brake..................................................................................... 4-85
4.6.3 Relief valve portion ...................................................................................... 4-86
4.6.4 Reverse prevention valve ............................................................................ 4-88
4.6.4.1 Operation drawing ............................................................................... 4-88
4.6.4.2 Explanatory drawing of effects ............................................................ 4-89
4.6.5 Center swivel joint ........................................................................................ 4-91
4.6.6 Travel motor ................................................................................................. 4-93
4.6.6.1 Operation of components .................................................................... 4-95
4.6.7 Valve control system .................................................................................. 4-107
4.6.8 Pilot valve.................................................................................................. 4-109
4.6.8.1 Work equipment and swing pilot valve .............................................. 4-109
4.6.8.2 Travel PPC valve ...............................................................................4-113
4.6.9 Solenoid valve.............................................................................................4-117
4.6.10 Accumulator ..............................................................................................4-118
4.6.11 Pilot oil
fi
lter ...............................................................................................4-119
4.6.12 Pump oil pressure sensor ........................................................................ 4-120
4.6.13 Hydraulic cylinder..................................................................................... 4-121
4.6.14 Work equipment ....................................................................................... 4-123
4.7 Air Conditioning System....................................................................................... 4-129
4.7.1 A/C components layout drawing ................................................................ 4-130
4.7.2 Control panel.............................................................................................. 4-131
4.7.3 Circuit diagram ........................................................................................... 4-132
4.7.4 Refrigeration principle ................................................................................ 4-134
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