Kubota GR1600EC2, Workshop Manual, Page: 126 / 241

2-M7
GR1600EC2, WSM TRANSAXLE
(4) Charge Pump
The charge pump revolves in combination with pump
shaft to draw oil from the transaxle case, and feed oil to
the charge circuit.
The charge pump is necessary to make up for
leakage from the pump and motor, preventing system.
Condition
• Engine Speed : Rated speed
• Oil Temperature : 50
°
C (122
°
F)
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(5) By-pass Valve
Normally, when the engine is stopped, the pump shaft
and pump cylinder block engaged with it do not rotate.
Thus, the motor shaft does not rotate.
However, pressing the by-pass valve in the center
section permits moving the machine with human power
while the engine is stopped. The following paragraphs
describe this mechanism :
Pressing the by-pass valve connects the forward and
reverse loops in the center section. This allows oil to flow
between the forward and reverse loops through the by-
pass valve to rotate only the motor cylinder block.
This means that pressing the by-pass valve while the
engine is stopped, that is, while the pump shaft is not
rotating, permits rotating the motor shaft engaged with
the motor cylinder block.
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Charge relief
pressure
Factory spec.
0.3 to 0.5 MPa
3.1 to 5.1 kgf/cm
2
43.5 to 72.5 psi
(1) Internal Snap Ring
(2) Oil Seal
(3) O-ring
(4) Charge Pump Housing (5) Spring (Charge Relief Valve)
(6) Steel Ball (Charge Relief
valve)
(1) By-pass Spring
(2) By-pass Spool (3) By-pass Plug
KiSC issued 07, 2006 A