A hand held rotary hammer, comprising: a spindle for rotatingly driving a tool or bit; a hammering mechanism (38, 58, 64) for generating repeated impacts on a tool or bit mounted at a forward end of the spindle; a spindle rotary drive train (41, 5, 10, 43) for rotatingly driving the spindle; an overload clutch in the spindle rotary drive train for transmitting rotary drive to the spindle below a predetermined torque and for cutting transmission of rotary drive above the predetermined torque; and a mode change mechanism (126, 128) for selectively cutting off the rotary drive to the spindle; wherein the overload clutch has a first mode of operation in which the overload clutch transmits rotary drive to the spindle below the first predetermined torque and stops transmission of rotary drive above the first predetermined torque; and a second mode of operation in which the overload clutch transmits rotary drive to the spindle below the second predetermined torque, different from the first predetermined torque, and stops transmission of rotary drive above the second predetermined torque; and characterised in that the overload clutch comprises two driven gears (13c, 13d), a driving gear, a first set of clutch balls adapted to engage the driving gear at a first distance from the axis of rotation thereof for coupling the driving gear and one of the driven gears below a first predetermined torque, and a second set of clutch balls adapted to engage the driving gear at a second distance from the axis of rotation thereof for coupling the driving gear and the other driven gear below a second predetermined torque, and wherein the overload clutch further has: a third mode of operation in which the overload clutch cuts off rotary drive to the spindle in response to the mode change mechanism. a spindle for rotatingly driving a tool or bit; a hammering mechanism (38, 58, 64) for generating repeated impacts on a tool or bit mounted at a forward end of the spindle; a spindle rotary drive train (41, 5, 10, 43) for rotatingly driving the spindle; an overload clutch in the spindle rotary drive train for transmitting rotary drive to the spindle below a predetermined torque and for cutting transmission of rotary drive above the predetermined torque; and a mode change mechanism (126, 128) for selectively cutting off the rotary drive to the spindle; wherein the overload clutch has a first mode of operation in which the overload clutch transmits rotary drive to the spindle below the first predetermined torque and stops transmission of rotary drive above the first predetermined torque; and a second mode of operation in which the overload clutch transmits rotary drive to the spindle below the second predetermined torque, different from the first predetermined torque, and stops transmission of rotary drive above the second predetermined torque; and characterised in that the overload clutch comprises two driven gears (13c, 13d), a driving gear, a first set of clutch balls adapted to engage the driving gear at a first distance from the axis of rotation thereof for coupling the driving gear and one of the driven gears below a first predetermined torque, and a second set of clutch balls adapted to engage the driving gear at a second distance from the axis of rotation thereof for coupling the driving gear and the other driven gear below a second predetermined torque, and wherein the overload clutch further has: a third mode of operation in which the overload clutch cuts off rotary drive to the spindle in response to the mode change mechanism. a third mode of operation in which the overload clutch cuts off rotary drive to the spindle in response to the mode change mechanism.