Screwdriver
US4631992A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 10, 1986 |
| Grant date | Dec 30, 1986 |
| Priority date | — |
| Expiry date | Mar 10, 2006 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB25B23/145
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A power drive screwdriver that is constructed to automatically stop when a predetermined torque is reached. The screwdriver includes a housing having a pneumatically driven motor therein and an output shaft that is linked to the screwdriver bit through a releasable clutch. A control valve is positioned in the housing to control air flow to the motor. The position of the valve is controlled by a rod that extends through the shaft. A transverse slot extends through the shaft intersecting the bore therein and the transverse slot contains a pair of balls that are retained within the slot by a sleeve encircling the exterior of the shaft. Further, a reset member engages the screwdriver bit and also engages the balls to displace the balls in the slot in a direction to open the valve. When the predetermined torque is encountered, the sleeve moves upwardly, permitting the balls to separate and thereby letting the valve rod move to permit the valve to close.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.