GB1430458A - Power tools - Google Patents

Abstract

1430458 Power tools; drilling GKN SCREWS & FASTENERS Ltd 13 March 1974 [13 March 1973] 11921/73 Headings B3N and B3C A speed reduction device for a power tool has an input shaft 10 which is drivingly connectable to the output shaft of the power tool, input shaft being connected to a working bit 13 by way of a clutch 14, 15 which when engaged transmits the drive direct to the working bit at the same speed of rotation as the tool output shaft and input shaft 10, the clutch being biased into an engaged condition by a spring 11 located within the bit carrier 12. The clutch part 14, is fixed to the shaft 10 and the other part 15 is fixed for rotation with the planet cage 16 of an epicyclic gear means the sun gear 18 of which is also fixed to the shaft 10. The planet gear pinions 21 engage with the sun gear 18 and the outer ring gear 19 which in turn is connected to the device housing 20. This housing is rotatable relative to the shaft 10 and axially displaceable with respect thereto. In operation, the biasing action of the spring 11 maintains the clutch 14/15 engaged under all normal load conditions upon the working bit and the rotary drive is direct from the power source (not shown) so that the shaft 10 and the parts of the device rotate as a single unit. When a resistance is encountered by the working bit and an excess axial pressure is applied to the shaft 10, the spring is compressed the clutch 14/15 is disengaged and the housing is displaced to engage a further clutch 26/27 whereby the drive from the shaft 10 is transmitted at a lower speed but higher torque by way of the epicyclic gearing 19, 21 and 18.