TROUBLESHOOTING
H-26
H-26 Swing acceleration is poor or swing speed is slow (both left and
right, one direction only)
*
Carry out troubleshooting in the H/O mode.
YES
a) Swing acceleration is poor
4
Does condition
yes become normal
- when servo
assembly is
replaced?
5YE-s )
3-
Is discharge
Does LS shuttle
YE3 pressure of front
- valve move
- pump normal
NO smoothly?
when swing is
relieved ?
2_
NO
or in one direction
. [ Both left and right ] *
Is discharge
pressure of rear
pump normal when
swing is relieved?
H
l Front pump
discharge
pressure:
28.9 f 1.5 MPa
(295 * 15 kg/cm*)
NO
. Rear pump
discharge
pressure when
I
swing is relieved:
NO
1.8 2 0.2 MPa
(80 t 20 kg/cm*)
* Flow chart when speed is slow
gr
Defective LS valve
7
Y
l See STANDARD
NO
Go to Item 5
8
,
VALUE TABLE.
n
6
[One direction only]
l Min. 2.74 MPa
(Min. 28 kg/cm*)
l Engine at high
idling
l Turn swing lock
switch ON (lock).
yes Does control valve
- spool move
7
smoothly?
Is output pressure
, fat shuttle block
end) of PPC valve
_
normal?
compensation valve
normal, or does pres-
sure cwnpensation
valve piston move
* It is also possible to
interchange with other
compensation valve.
YES
II
NO
- Note:
After inspection, do not
forget to return to the
original position.
IO
l Same conditions
as for Item 6
l Remove PPC
shuttle block inlet
NO
hose. fit adapter,
and block tip.
(Note)
Note:
If the adapter for blocking the circuit is not available, interchange PPC hose of swing with one of bucket
(CURL, DUMP), boom (LOWER), or arm (IN).
b) When swing speed is slow
Change Item 2 marked with * under flow for a) Swing acceleration is poor, and omit Item 4 when carrying out
troubleshooting.
20-234
0
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