wsm wg972-e4, Workshop Manual

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ENGINE
WG972-E4, WSM
1-M7
[2] OIL PUMP
The oil pump is a trochoid pump, whose rotors have
trochoid lobes. The inner rotor (2) has 4 lobes and the
outer rotor (4) has 5 lobes, and they are eccentrically
engaged with each other. The inner rotor, which is driven
by the crankshaft through the gears, rotates the outer
rotor in the same direction, varying the space between
the lobes.
While the rotors rotate from (A) to (B) , the space
leading to the inlet port increases, which causes the
vacuum to suck in the oil from the inlet port.
When the rotors rotate to (C) , the space between
both rotors switches from the inlet port to the outlet port.
At
(D) , the space decreases and the sucked oil is
discharged from the outlet port.
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[3] RELIEF VALVE
The relief valve prevents the damage to the
lubricating system due to the high pressure of the oil.
This relief valve is a ball direct acting type, and is
best suited for low pressures.
When the pressure of the oil, forced by the pump,
exceeds the specified value, the oil pushes back the ball
(2) and escapes to the oil pan.
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[4] OIL FILTER CARTRIDGE
After lubricating, the lubricating oil brings back
various particles of grit and dirt to the oil pan. Those
particles and the impurities in the lubricating oil can
cause wear or seizure of the engine parts. It may also
impair the physical and chemical properties of the oil
itself.
The lubricating oil which is force-fed by the pump, is
filtered by the filter cartridge with the filter element (2).
When the filter element accumulates on excessive
amount of dirt and the oil pressure in the inlet line builds
up by 98 kPa (1.0 kgf/cm
2
, 14 psi) more than the outlet
line, the bypass valve (1) opens to allow the oil to flow
from the inlet into the outlet line, bypassing the filter
element.
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(1) Inlet Port
(2) Inner Rotor (3) Outlet Port
(4) Outer Rotor
(1) Spring
(2) Ball (3) Valve Seat
(1) Bypass Valve (2) Filter Element
KiSC issued 07, 2015 A