| 摘要 |
<p>A rotary hammer comprises a percussion mechanism (18, 22, 24) for impacting a tool bit (4) received by the hammer, and a rotary drive mechanism (12, 16) for rotating the bit, the percussion mechanism and the rotary drive mechanism being variable so that the ratio of rate of impacts on the bit to its rotational speed can be varied, for example by employing two independently controllable electric motors (6, 8). The hammer includes at least one sensor for detecting at least one property that is influenced by the operation of the hammer, for example an accelerometer (26) or a detector for determining the instantaneous current consumption of the motors, and a processor that determines from the property a number of operational parameters. From the operational parameters the processor determines the desired ratio of impact rate to rotational speed of the hammer, and the hammer includes means for setting the impact rate and rotational speed in response to the processor. <IMAGE></p> |
