6-9
WHEN THE RCV LEVER IS IN THE ROLL BACK (retract) POSITION
If the RCV lever (4, bucket) is pulled left, the bucket spool is moved to roll back position by pilot oil
pressure from EH control block (6).
The oil from main pump (1) flows into main control valve (3) and then goes to the large chamber of
bucket cylinder by pushing the load check valve of the bucket spool.
The oil at the chamber of bucket cylinder (14) returns to hydraulic tank (22).
When this happens, the bucket roll back.
·
·
·
·
11
T
A1
P1
X1
X2
X3
S1
B2
L3
L4
B1
L1
L2
S1
S2
X1
X2
PS
Aux
Bucket
Boom
Joystick
4
1
EH20
EH19
EH22
EH21
P
T
6(4)
3(2)
5(3)
2(1)
( ) : 2 Spool
EH18
EH17
To MCV
a3 b3 a1
b1
a2 b2
Return line
Fan & brake pump
Steering system
Return line
Steering valve
(EHPS) EF port
Steering valve
(EHPS) LS port
3
LH
B1
A1
B2
A2
LS
a2
b2
b1
a1
Pst
B3
A3
b3
a3
T
P
PS
PS
RH
Dump
Roll back
Up
Down
Floating
Bucket
Boom
Aux
23
22
25
24
12
11
26
28
28
29
6
5
4
4'
40
14
13
29
29
Control unit
(Electro-Hydraulic & Joysick steering)
5)
757F6WE07
Summary of Contents for HL955
Page 557: ...7 6 MEMORANDUM MEMORANDUM ...
