G-1 G-1
General description of telescoping system
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WG02-0480E
G-1 General description of telescoping system
1. Functions of units
1.1 Telescoping cylinder
This cylinder is located inside the boom.
It is connected to the base boom section and the 2nd boom section with pins to extend and retract the 2nd
boom section.
1.2 Counterbalance valve
This valve serves to prevent the telescoping cylinder from spontaneously retracting by a load during a boom
retracting operation, and to make it retract at a speed in proportion to the oil quantity supplied to the
telescoping cylinder.
This valve further serves to prevent the telescoping cylinder from retracting when the piping between this
valve and the manual control valve is damaged.
2. Wire rope mechanism
The 3rd, 4th and top boom sections are extended/retracted by the following five wire rope mechanisms.
2.1 Wire rope mechanism A (for extending the 3rd boom section)
This mechanism extends the 3rd boom section at the same time when the 2nd boom section is extended.
The wire ropes are passed within the boom in the following order.
・Base boom section → sheave at the front end of the telescoping cylinder → rear end of the 3rd boom
section
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