Kubota U25-3 Repair Manual

U20-3, U25-3 WSM Hydraulic system (Mechanism section)
IV-M-1
IV. Hydraulic system (Mechanism section)
A. Features of hydraulic system ....................................................................................................IV-M-2
B. Hydraulic system specifications ................................................................................................IV-M-3
C. Main pump ...................................................................................................................................IV-M-4
a. Strueture & specifications .................................................................................................... IV-M-4
b. Performance curve ................................................................................................................IV-M-5
c. Operating principle ................................................................................................................ IV-M-7
D. Contrel valve ................................................................................................................................IV-M-8
a. Specifications ......................................................................................................................... IV-M-8
b. General view of control valve .............................................................................................. IV-M-9
c. Sectional view ......................................................................................................................IV-M-11
d. Arm regeneration circuit .....................................................................................................IV-M-16
e. Boom anti-fall valve .............................................................................................................IV-M-17
f. Straight travel circuit ...........................................................................................................IV-M-22
g. Simultaneous operation of boom & bucket .....................................................................IV-M-24
h. Relief valve/Anti-cavitation valve ......................................................................................IV-M-25
i. Automatic air bleeding in hydraulic pilot section ............................................................IV-M-26
E. Pilot valve ...................................................................................................................................IV-M-27
a. Structure & specifications....................................................................................................IV-M-27
b. Pilot valve control diagram .................................................................................................IV-M-29
c. Functions ..............................................................................................................................IV-M-30
F. Swivel motor ..............................................................................................................................IV-M-33
a. Structure & specifications ..................................................................................................IV-M-33
b. Operating principle ..............................................................................................................IV-M-34
c. Function of negative brake ................................................................................................IV-M-36
G.Rotary joint (Swivel joint) .........................................................................................................IV-M-37
H. Travel motor U20-3 (Fujikoshi) ...............................................................................................IV-M-39
a. Stracture & specifications ..................................................................................................IV-M-39
b. Operating principle ...............................................................................................................IV-M-40
U25-3 (Kayaba) .......................................................................................................................IV-M-44
a. Structure & specifications ..................................................................................................IV-M-44
b. Operating principle of motor ..............................................................................................IV-M-46
c. Operating principle of counter valance valve ..................................................................IV-M-47
d. Function of Hi-Lo change ...................................................................................................IV-M-50
e. Function of reduction gear .................................................................................................IV-M-52
f. Function of anti-cavitation valve ........................................................................................IV-M-53
I. Hydraulic circuit diagram .........................................................................................................IV-M-58
a. U20-3 Fixed undercarriage ................................................................................................IV-M-58
b. U20-3 Retractable undercarriage .....................................................................................IV-M-59
c. U25-3......................................................................................................................................IV-M-60
d. Hydraulic components layout ............................................................................................IV-M-61

Kubota U25-3 Specifications

General

Brand	Kubota
Model	U25-3
Category	Excavators
Language	English