Stanley MB05, User Manual

MB05 User

 Manual ◄ 13

BLANK FIRING

To understand “Blank Firing”, the operator needs to be 

aware that the tool bit is able to drop down in the lower 

body cavity, far enough so that the piston cannot strike it, 

when the tool bit is not in contact with the work surface. 

“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 carrier components and 

may result in failure of one or more components. Exces-

sive “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 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 position, the 

piston 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 carrier boom components. “Blank Firing” of this 

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 

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 

piston’s stroke and the energy of the piston will be ab-

sorbed by breaker components and excavator boom 

components. “Blank Firing” of this type can be experi-

enced 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.

Breaker tool binding can cause erratic breaker opera-

tion and premature wear on the tool shank. Breaker tool 

binding is caused by failure to direct the down force in 

the direction of the tool bit.

Excessive side force cocks the tool in its bore, prevents 

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.
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 oxy-acetylene torch

Breaker tool bit binding

CAUTION

Do not pry with bit and breaker. The tool bit may 

break causing injury.

OPERATION