US Patent 9168649 Hammer drill

A hammer-drill including a body in which is mounted a motor and a hammer mechanism which is driven by the motor; a tool holder mounted on the front of the body and which is capable of holding a cutting tool, the hammer mechanism being capable of imparting impacts to the cutting tool, when held by the tool holder; a rear handle, moveably mounted onto the rear of the body via at least one movement control mechanism and which is capable of moving towards or away from the body; a biasing mechanism which biases the rear handle away from the body.