Patent ID: 8449425
Filing Date: 2013-05-28
Classification: B25B,B25F

Abstract:
1. An electric tool comprising: an electric motor activated by an ON-operation of a switch lever; a speed changing device configured to reduce a rotational power of the electric motor and output the same to a spindle; wherein the speed changing device includes a first stage planetary gear mechanism on an upstream side of a power transmitting path and a second stage planetary gear mechanism on a downstream side thereof, the speed changing device being configured to be switched from an initial high-speed low-torque output state for outputting a high-speed low-torque to the spindle to a low-speed high-torque output state for outputting a low-speed high-torque to the spindle according to increase in an external torque applied to the spindle, wherein in the initial high-speed low-torque output state, an internal gear of the second stage planetary gear mechanism is positioned at a rotation-allowed position where the internal gear of the second stage planetary gear mechanism engages with a carrier of the first stage planetary gear mechanism; wherein in the low-speed high torque output state, the internal gear of the second stage planetary gear mechanism is disengaged from the carrier of the first stage planetary gear mechanism and is displaced to a rotation-restricted position in which the rotation is restricted; a speed change lock mechanism configured to lock the low-speed high-torque output state of the speed changing device; a reset mechanism configured to release the speed change lock mechanism on the basis of an OFF-operation of the switch lever and reset the speed changing device to the initial high-speed low-torque state; and a delaying mechanism configured to shift in terms of time between timing of stopping the electric motor achieved by the OFF operation of the switch lever and timing of releasing the speed change lock mechanism achieved by the resetting mechanism.