Komatsu PC200-8M0, Shop Manual

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SEN06120-00
10-402
46
PC200, 200LC, 220, 220LC-8M0
402 Hydraulic system, Part 2
Functions and operation by valve
In boom “LOWER” operation
q
When operating boom “LOWER”, the pilot pressure from the PPC valve pushes pilot piston (2).
q
The pressurized oil of the boom cylinder bottom flows from orifice (c) to drain port (T) through orifice (a)
and chamber (b).
q
Chamber (b) inside poppet and drain port (T) are interconnected, and the pressure of chamber (b)
drops.
q
As the pressure of chamber (b) becomes less than the pressure of port (B), poppet (5) opens.
q
As poppet (5) opens, the pressurized oil from port (B) flows to port (A) and then flows to the control
valve.