There are 3 main types of Kawasaki pump applied on hydraulic excavators:
K3V112 schematic hydraulic pump
K5V140 schematic hydraulic pump
Flow Control (Decrease flow)
Control valve spools are neutral, High negacon pressure comes up to pilot piston.
The pilot piston makes spool move to decrease oil flow.
Flow Control (Increase flow)
When move spools, Low negacon pressure comes up to pilot piston.
The pilot piston makes spool move to increase oil flow.
Power Control (Decrease flow)
System pressure is getting increase, compen piston is moved.
The compen piston makes control spool move to decrease oil flow.
Power Control (Increase flow)
System pressure is getting decrease, compen piston is moved.
The compen piston makes control spool move to increase oil flow.
Power shift curve (Power Mode)
Power Shift (K3V112 pump)
Standard mode : 0mA (0 bar)
Power mode : 600mA (29 bar)
Power Shift (K5V140 pump)
Standard mode : 0mA (18 bar)
Power mode : 600mA (0 bar)
Inner Structure of Hydraulic Pump
Body of hydraulic pump
▷ Two variable displacement axial piston pumps connected in series
▷ A geartype pilot pump mounted on the second main pump
▷ Flow output controled by regulators on each pump
Regulator (Negacon Control)
Regulator (Power Control)
▶ Negacon Pressure
▶ Flow Decrease Circuit
▷ High Negacon Pressure (Pi) => Low Oil Flow (Qi)
▶ Flow Increase Circuit
▷ Low Negacon Pressure (Pi) => High Oil Flow (Qi)
▷ POWER pump = (Pd * Q )/450 where Pd in bar, Q in lpm
▷ POWER pump ≤ POWER engine
▷ Cross Over Power Control (or Summation Power Control)
▶ Overload Protection Circuit
▷ High Average Pressure (Pd) => Low Oil Flow (Qd)
Final Oil Flow Determination
▶ Final Q determined by Regulator
▶ Concept of Powershift Control
▶Operating of Powershift Control
▶Characteristic of powershift valve
▷ ▷ Reference Only
▷ ▷ The characteristic differs as per pump model.
Adjustment of hydraulic pump
▶ Input Power – Outer Spring of Power control
▶ Input Power – Inner Spring of Power control
▶ Negacon Control
▶ Minimum Discharge Flow
▶ Maxmum Discharge Flow