DRIVE TOOL Russian patent published in 2013 - IPC B25F5/00 

FIELD: process engineering.

SUBSTANCE: invention relates to hand tools. proposed tool comprises power supply 115, rpm changeover mechanism 117 and tool adapter 113. Said rpm changeover mechanism 117 comprises first and second rotary shafts 123, 125 arranged in parallel, first electric power transfer path P1 supported by first gearing and first coupling 141 and second electric power transfer path P2 supported by second gearing and second coupling 145. Said electric power transfer path is changed between first path P1 and second path P2 while first and second gearings are retained engaged by shift of said first and second couplings 141, 145 from electric power transfer state and shutoff state in compliance with the load applied to cutting tool 113.

EFFECT: smooth speed changeover.