Stanley Black & Decker MBX15 Power Hammer User Manual


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12 ► MBX15 User Manual
Excessivesideforcecocksthetoolinitsbore,pre-vents
proper movement and causes premature tool shank
andbushing wear.Since thebreaker toolbit mustbe
pushed up into the breakerto operate, a binding tool
preventsthebreaker fromoperatingcorrectly.Binding
alsocausesthetoolbitandtoolbushingstoseizeand
oftenresultsinbreakageofoneormorebreakercom-
ponents.Alwaysdirectthedownpressureforceinaline
towardthepointoftoolcontactwiththework.
NOTICE
DONOTprywiththetoolbitandbreaker.
Pryingwilldamagethetoolbitandassociated
breakercomponents.
Movingrockswiththetoolbitisanothermethodofbind-
ingthetoolbit.Thispracticeshouldbeavoidedasitmay
causetoolbitfailure.
Rebar reinforced concrete introduces the problem of
concretechunksbeingheldtogetherbytherebarafter
theconcretehasbeenbroken.Thebestapproachtothis
problemistouseachiselpointtoolwhichpermitscut-
tingtherebarwiththebreaker.Anothermethodistope-
riodicallycuttherebarwithanoxyacetylenetorch.
BLANK FIRING
To understand “Blank Firing”,theoperatorneedsto
beawarethatifthetoolbitisnotpressedagainstthe
worksurfacethetoolbitwilldropdowninthelowerbody
cavityfarenoughsothatthepistoncannotstrikeit.Blank
ringoccurswheneverthebreakerisoperatingandthe
pistonisnotabletostrikethetoolbitsolidlyornotstrike
thetoolbitatall.BlankFiringaccelerateswearandtear
onbreakerandexcavatorcomponentsandmayresultin
failureofoneormorecomponents.Excessiveblankr-
ingmaybeconsideredequipmentabuseandmayresult
invoidingwarranties.
Break-throughordifcultsurfacecontactresultsinblank
ringwhenthematerialbeingbrokenfracturesandthe
toolbitisnolongerin“hardcontact”withthematerial
butisstillpushedhighenoughinthelowerbodycavity
sothatthepistoncanstrikeit.Inthiscondition,thepis-
tonstrikesthetoolbitandthetoolbit,inturn,isdriven
againsttheretainingpinsbecauseitisnotinsufcient
contactwiththematerialtobebroken.Theenergyisab-
sorbedbytheretainingpins,otherbreakercomponents,
andtheexcavatorboomcomponents.Blankringofthis
typecanbeexperiencedintrenchworkwhereobtain-
ingstrikingcontactwiththeworksurfaceisdifcultor
thewrongtoolbitisused,orinatrockworkwherethe
operatorfailstostopoperationofthebreakerwhenslip-
page,fracturingormaterialbreak-throughoccurs.
Blankringasaresultofoperatorerroroccurswhenthe
toolbitisnotincontactwiththeworksurfacetobebro-
kenandisallowedtodropdowninthelowerbodycav-
itysothatthepistonisnotabletostrikeit.Instead,the
downwardmovementofthepistonwillbestoppedbyan
internaloilcushionlocatedatthebottomofthepiston’s
strokeandtheenergyofthepistonwillbeabsorbedby
breakercomponentsandexcavatorboomcomponents.
Blankringofthistypecanbe experiencedwhenthe
operatorfailstostopoperationofthebreakerwhenthe
materialfracturesormaterialbreak-throughoccurs,or
duringre-positioningofthebreaker.
Whileblankringcannotalwaysbeavoided,itcanbe
kepttoaminimumbyavoidingtheaboveconditionsas
muchaspossible.
OPERATION
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