Oil Pump Descriptions; Trochoid Type - Honda Motorcycle Service Manual

LUBRICATION
OIL PUMP DESCRIPTIONS
T R O C H O I D T Y P E
The trochoid-type oil pump is the most common oil pump
design used in 4-stroke engines. It is designed to turn t w o
rotors within a casing, with an inner rotor fixed on the pump
shaft (drive shaft) and an outer rotor on its circumference.
When the inner rotor is turned by means of the oil pump shaft,
the outer rotor also turns, with the clearance between the t w o
rotors varying. Lubricant is drawn through by suction when
the clearance is enlarged. Oil is delivered to the opposite side
through this clearance and is then routed into the discharge
passage when the clearance lessens. The more teeth the inner
and outer rotors have, the less the amount of pulsation. The oil
flow volume increases in direct proportion with the increase in
thickness of the rotor dimension.
Some models have a double rotor trochoid-type oil pump
which collects oil directly from both the oil cooler and the
sump
1
GASKET
PUMP BODY
I
O ~ T E R ROTOR
INNER ROTOR
OUTER ROTOR DISCHARGE
% .
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1
INNER ROTOR
I
MAIN GALLERY
Date of Issue: Sep., 1988
O
HONDA MOTOR CO., LTD.
4-7
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