8-M12
M6800 · M6800S · M8200 · M9000, WSM
HYDRAULIC SYSTEM
6. RELIEF VALVE
Q Relief Valve
M6800(S), M8200 and M9000 use a pilot-operated
relief valve. This relief valve is suitable for a high
pressure and large volumetric flow, and has better
pressure override performance than direct acting relief
valves.
This relief valve consists of a pilot valve (4) and main
valve (8). The pilot valve (4) is a trigger which controls
the main valve (8).
When the oil pressure in the circuit is lower than the
setting pressure, the pilot valve (4) and main valve (8)
are closed by the spring (3) and (7).
W1015305
Q Relief Valve in Operation
As the oil pressure in the circuit rises, so does the
pressure in the chamber “C”. When it reaches the pilot
valve setting pressure, the pilot valve (4) opens. This
releases oil in the chamber “C” to the transmission case.
Accordingly the oil in the circuit flows to the chamber “C”
through the passage (10).
The resulting pressure drop in the chamber “C”
causes the main valve (8) open. The oil in the circuit then
flows out to the transmission case, preventing any further
rise in pressure. The relief valve close again when the oil
pressure in the circuit drops below the setting pressure.
(Reference)
• Relief valve setting pressure
Condition
• Engine speed ............ Maximum
• Oil temperature ......... 45 to 55 °C
113 to 131 °F
W1015453
(1) Relief Valve Body
(2) Adjuster
(3) Spring
(4) Pilot Valve
(5) Valve Seat
(6) Sensing Passage
(7) Spring
(8) Main Valve
(9) Valve Seat
(10) Passage
P : P Port
Use for Individual Flow Type
Pump
Use for Combine Flow Type
Pump
18.6 to 19.1 MPa
190 to 195 kgf/cm
2
2702 to 2773 psi
19.1 to 19.6 MPa
195 to 200 kgf/cm
2
2773 to 2845 psi
(3) Spring
(4) Pilot Valve
(5) Valve Seat
(8) Main Valve
(9) Valve Seat
(10) Passage
(C) Chamber “C”
P : P Port
T : T Port
To Next Page
Loading...
Need help?
General
