AJ 1000M, Operations Manual & Parts List

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Blank Firing
To understand "Blank Firing", the operator needs to be aware that if the chisel is not pressed
against the work surface, the chisel will drop down in the lower body cavity far enough so that
the piston cannot strike it. Blank firing occurs whenever the breaker is operating and the piston is
not able to strike the chisel solidly or not strike the chisel 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 firing may be considered equipment abuse and may result in voiding warranties.
Break-through or difficult surface contact results in blank firing when the material being broken
fractures and the chisel 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 piston
strikes the chisel and the chisel is driven against the tool pins because it is not in sufficient contact
with the material to be broken. The energy is absorbed by the chisel pins, stop pins, front head
chisel pin area, other breaker components, and the excavator boom components. Blank firing of this
type can be experienced in trench work where obtaining striking contact with the work surface is
difficult or the wrong chisel is used, or in flat rock work where the operator fails to stop operation
of the breaker when slippage, fracturing or material break-through occurs.
Blank firing as a result of operator error occurs when the chisel is not in contact with the work
surface to be broken and is allowed to drop down in the lower body cavity 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 pistons's stroke and the energy of the piston will
be absorbed by breaker components and excavator boom components. Blank firing 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 firing cannot always be avoided, it can be kept to a minimum by avoiding the above
conditions as much as possible.