US Patent 10022852 Impact tool

An electrical hammer (100) comprises a main housing (101), a hand grip (500) connected to the main housing (101) via a compression coil spring (321). In the electrical hammer (100), a hammer bit (119) is driven by a first motion converting mechanism (120) and thereby a hammering operation is performed. During the hammering operation, the hand grip (500) is moved against the main housing (101) in a state that biasing force of the compression coil spring (321) is applied on the hand grip (500). Further, the electrical hammer (100) comprises a second motion converting mechanism (220) which drives a counterweight (231).