Negacon Relief Valve - Doosan DX140R Shop Manual

Negacon Relief Valve

Negacon Relief Valve Operation
Figure 35
Generation of Signal Pressure
The oil supplied through the pump port (P1) flows to the tank
path through the neutral path (L1) and the negacon orifice (D) at
the neutral downstream path (A).
In this process, pressure is generated in the path (B) by the
negacon orifice (D), and the pressure is induced in the negacon
signal pressure port (Ps1) through path (E).
When the main spool that is upstream of the neutral downstream
path (A) is activated, the oil flow through the neutral downstream
path (A) is decreased and the cegacon signal pressure is
reduced.
Relief Operation
In the event that there is excessive oil flow in the neutral
downstream path (A), the pressure generated in path (B) by the
negacon orifice (D) is induced to the back chamber (C) of the
poppet. The poppet is activated by the differential pressure
generated by the difference in the hydraulic area between the
path (B) and the back chamber (C). When this poppet is
activated, oil flows to the tank path (Ta) through path (B) and the
drill hole path (F) of the plug, preventing excessive pressure in
the negacon signal pressure port.
Main Control Valve SP001029
Page 44