Stanley Black & Decker MBX138 thru MBX608 user manual Blank Firing

OPERATION

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.

type can be experienced in trench work where obtain- ing striking contact with the work surface is difficult or the wrong tool bit is used, or in flat rock work where the operator fails to stop operation of the breaker when slip- page, fracturing or material break-through occurs.

Blank firing 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 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.

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 firing 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 fir- ing 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 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 sufficient 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 firing of this

MAXFORCE BREAKER User Manual ◄ 13