Manitowoc NATIONAL CRANE 900A - ANTI-TWO BLOCK TROUBLE DIAGNOSIS - HYDRAULIC (CONTINUED)

5-1
72,"7+ ^j
$74<)$6&'$
%43'$4&
4&$3)'%%
Purge air from unloader
circuits. See procedure in
this manual
Functions operate correctly ? Problem solved
Are all three functions
shut down ?
Examine solenoid valve
for sticking spool
Work with individual
section that is shut down
Disconnect drain line from
outlet end of unloader valve
Install cap fitting to plug outlet
end of unloader valve
Operate function
Function operates correctly
Oil is passing through the
check valve in another
unloader
Cap each of other
unloaders in turn to identify
the unloader with the faulty
check valve
Flush to remove
contamination otherwise
replace unloader valve
The poppet in the unloader
is not seated. Remove
unloader and flush to
dislodge contamination
Reinstall, retest and replace
unloader if problem persists
NO
YES
NOYES
YES NO
$*3$&$$3$&'%###58



























Reference Only