When working large wide objects, it is efficient to work little by little from the edge to the center and do not punch continuously the same point for more than 30 seconds. Careful, if you strike one part for a long time without any moving, then this can cause damages.       Inclining the chisel to the surface of crushing one can cause breakages of chisels, or can accelerate abrasion of the ring bushing and the front cover.       Dropping the breakers not only gives no crushing forces but also can cause critical damages to the breakers and equipments. It is desirable to operate all the time by locating the chisel safely onto the object to be crushed.       When Chisels hits the objects like concretes that relatively flat and weak, the chisel can stuck in an object. At this situation, continuous striking will generate high-temperature heat on the end of the chisels can shorten the lifetime. It is desirable to crush by bending the breakers back and forth little by little while working. But, careful. Excessive bending can break the chisels.       Do not use the chisel as lever even though an object is so weak. Or, it can cause critical damages to the chisel and the body of the breaker. Be careful.       Since there is no safety device for lifting on the breakers, so do not excessive lifting. It will not tolerates the lifting weights.