Kubota WSM STa-30, Workshop Manual, Page: 259 / 359

8-M3
ST
α
-30, ST
α
-35, WSM STEERING
3. HYDRAULIC PUMP
The steering system hydraulic pump fed the oil drawn
from the transmission case through the oil filter to the
control valve. The steering system hydraulic pump is
driven by the engine fuel camshaft.
This hydraulic pump is pressure loading type gear
pump with high volumetric efficiency.
(Reference)
W1012894
■
Operation
The hydraulic pump has two meshing gears (2), (3)
whose teeth run close to the casing (1). One gear is a
drive gear which drives the driven gear.
When the drive gear is driven in the direction of the
arrow by the fuel camshaft, the gear traps oil between the
gear teeth and the casing. The higher the engine speed,
the more the pump discharges.
W1013163
The pressure loading system automatically
decreases the clearance between the gear and the
bushings. A small amount of pressurized oil is fed
behind the bushings, pressing them against the gears
and forming a tighter seal against leakage. Therefore,
leakage from the delivery side (high pressure) to the inlet
side (low pressure) does not increase even if the
pressure on the delivery side increases.
W1013265
Pump discharge per revolution
6.128 cc/rev.
0.373 cu.in./rev.
Pump discharge
displacement
At 2800
rpm
engine
speed
At no-
load
14.0 L/min.
3.70 U.S.gal./min.
3.08 Imp.gal./min.
(1) Power Steering Hydraulic
Pump
(2) 3-Point System Hydraulic
Pump
(3) Pump Body
(4) Bushing
(5) Drive Gear
(6) Side Plate
(7) Bushing
(8) Driven Gear
(9) Double Ring
(1) Casing
(2) Gear
(3) Gear A: Outlet
B: Inlet
(1) Loading Pressure
(2) Gear
(3) Pressure Introducing Port
(4) Bushing A: Outlet
B: Inlet
KiSC issued 11, 2006 A