Hitachi ZW180, Техническое руководство

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COMPONENT OPERATION / Pump Device
T3-1-10
Increasing Flow
1. When the control lever stroke is larger, pressure
difference (difference between pressure Pi1 and
Pi2) arising at the flow control valve in the control
valve is reduced.
2. Force due to spring (1) and pump control
pressure Pi2 pushes spool 1 (3) and spool 1 (3)
moves toward the arrow.
3. Therefore, the circuit of servo piston 1 (10) is led
to the hydraulic oil tank.
4. As pilot primary pressure Pg is always applied to
servo piston 2 (12), swash plate (11) tilts toward
the flow increasing direction.
5. Movement of swash plate (11) is transmitted to
sleeve 1 (2) through the feedback lever link (13).
Sleeve 1 (2) moves toward the movement of
spool 1 (3).
6. When sleeve 1 (2) has moved the same distance
as spool 1 (3) servo piston 1 (10) is not connected
to the hydraulic oil tank. Therefore, servo piston 1
(10) stops and the flow increase is completed.
T4GB-03-01-006
1 - Spring 10 - Servo Piston 1
2 - Sleeve 1 11 - Swash Plate
3 - Spool 1 12 - Servo Piston 2
4 - Piston 13 - Feedback Lever Link
Pd1 - Own Pump Pressure Pi1 - Pump Control
Pressure 1
ST - Pump Torque Control
Pressure
Pi2 - Pump Control
Pressure 2
T - Returning to Hydraulic Oil
Tank Pg - Primary Pilot Pressure
(From Pilot Pump)
Flow (Q)
Pump Control Pressure (Pi1-Pi2)
0
3 2 1
4
Pi1 T
Air
Bleeding
Pi2
Pg
T
ST
Pd1
T
Increase Decrease
Displacement Angle
10 12
13