MTZ 1220.3 - Page 176

MTZ 1220.1/1220.3 Section М. Possible failures
М8
Defect
,
external
manifestation
Way of elimination
Ingress of foreign particles
under the spool
edge.
Remove the cover from the regulator-
distributor, set the position handle to the
foremost position. The spool valve lock ring
shall rest against the body of the regulator-
distributor. Move the position handle to the
rear position. The spool valve shall move
upwards to the dis
tance of at least 7 mm. If
not so, remove the regulator-
distributor,
clean it from foreign particles jammed be-
tween the edges of the spool va
lve and
body.
The loaded mounted attachment is not lifted or is lifted too slowly
The fault becomes apparent as oil in the
hydraulic system is warmed up –
the pump
is faulty.
Check the capacity of the pump. If the pump
efficiency is below 0.7, replace the pump.
The fault becomes apparent at any oil tem-
perature – clogging of the overload valve.
Remove the regulator-
distributor, take the
bypass valve away and wash it and the cas-
ing in diesel fuel.
The loaded mounted attachment is lifted slowly; after stop
ping the
diesel engine
,
the spontaneous mounted attachment lowering is noticeable by eye, the position
corrections are frequent, the pressure “hanging-up” is possible
Destruction of the rubber seals of the regu-
lator-distributor.
Remove the regulator-distributor and re-
place rubber seals by new ones.
The pump is not unloaded over the whole range of travel of the mounted attac
h-
ment with load when employing the position method of adjustment on reaching the
specified position by the mounted attachment
In case of minor displacements of the posi-
tion handle towards the lowering position,
the pump is shortly unloaded, on stopping
the diesel engine the leak-
proofness is
normal
Jamming or loss of sealing of the valve-
accelerator.
Remove the regulator-distributor;
take away
the bypass valve, disassemble and wash it.
If necessary, hammer the valve ball to its
seat.
At move of position handle to side of lowering pump does not unload, by
diesel
engine stop, tightness is normal
Decapsulation of valve of pressure adjust-
ment.
Turn out conical plug on upper surface of
regulator, remove spring, ham
mer ball of
valve to its seat, install parts back on their
places.
The loaded mounted attachment independently falls to a small size after mounted
implement achieves specified position of position handle («subsidence» of
mounted implement)
Decapsulation of antishrinking valve. Remove regulator-
distributor, turn out plug
of antishrinking valve, remove spring, ham-
mer ball to its seat, install parts back on
their places.