Proper position must be applied for an effective use of hammering force. When position is incorrect, hammering energy of the piston is too weak to break rocks. Instead, hammering force applies shocks to the breaker itself and the arm and boom of the base machine, thereby resulting in damage to those parts.

On the contrary, when position is excessive enough to break rocks with the front of the base machine raised, the machine may suddenly tilt forward the moment rocks are broken. Then, the breaker body or the end of bracket may violently hit against rocks and result in damage.

It is undesirable to carry out hammering under the below condition, because vibrations during hammering may be transmitted to the tracks of the base machine. During hammering, however, proper position must be always applied to the breaker. Special care must be taken not to hammer under abnormal condition.