Automatic jaw control for reversible power tool
First Claim
1. In a reversible power tool having a rotary drive shaft carried by a drill housing and having a chuck engageable for rotation with said drive shaft and formed with a jaw guide, chuck jaws constrained by said jaw guide for radial advancement and retraction relative to the axis of said drive shaft, chuck jaw reciprocating means journaled relative to said jaw guide, and coupled to said chuck jaws to selectively advance and retract said chuck jaws between completely advanced and completely retracted positions when said chuck jaw reciprocating means and said jaw guide are subjected to relative rotation in opposite directions, and manually actuable clutch means for engaging and disengaging said chuck jaw reciprocating means relative to said drill housing to respectively allow and prevent relative rotation between said jaw guide and said chuck jaw reciprocating means, wherein said clutch means includes a clutch actuator mounted for movement relative to said drill housing, clutch interface means for engaging said drill housing to said chuck jaw reciprocating means, biasing means urging said clutch interface means into disengagement and actuable coupling means for overcoming said biasing means and moving said clutch interface means into engagement at a mechanical advantage by said clutch actuator, the improvement comprising decoupling means for forcing said clutch interface means into disengagement as said chuck jaws approach said completely retracted position despite actuation of said coupling means.
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Accused Products
Abstract
In a reversible power tool, such as an electric drill, a clutch mechanism is coupled to selectively connect and disconnect a chuck jaw reciprocating means to advance and retract the jaws of a chuck or to allow the chuck jaw reciprocating means to be carried in rotation with the chuck jaws. According to the improvement the clutch mechanism is decoupled as the chuck jaws approach a position of complete retraction, despite actuation of a coupling mechanism which would otherwise prevent the chuck jaw reciprocating means and the chuck jaws from turning together in rotation. The decoupling mechanism prevents damage to the chuck which occurs in prior devices when the chuck jaws are driven longitudinally beyond the designed limit for complete chuck jaw retraction. Also, an annular workpiece holder is releasably secured to the chuck to hold a workpiece in axial alignment with the tool drive shaft to safeguard against accidental injury to the fingers of an individual operating the tool. The chuck is engaged with the drive shaft at a tapered interface, in addition to a conventional threaded connection. A means is provided for immobilizing the drive shaft relative to the tool housing to facilitate removal of the chuck.
76 Citations
5 Claims
- 1. In a reversible power tool having a rotary drive shaft carried by a drill housing and having a chuck engageable for rotation with said drive shaft and formed with a jaw guide, chuck jaws constrained by said jaw guide for radial advancement and retraction relative to the axis of said drive shaft, chuck jaw reciprocating means journaled relative to said jaw guide, and coupled to said chuck jaws to selectively advance and retract said chuck jaws between completely advanced and completely retracted positions when said chuck jaw reciprocating means and said jaw guide are subjected to relative rotation in opposite directions, and manually actuable clutch means for engaging and disengaging said chuck jaw reciprocating means relative to said drill housing to respectively allow and prevent relative rotation between said jaw guide and said chuck jaw reciprocating means, wherein said clutch means includes a clutch actuator mounted for movement relative to said drill housing, clutch interface means for engaging said drill housing to said chuck jaw reciprocating means, biasing means urging said clutch interface means into disengagement and actuable coupling means for overcoming said biasing means and moving said clutch interface means into engagement at a mechanical advantage by said clutch actuator, the improvement comprising decoupling means for forcing said clutch interface means into disengagement as said chuck jaws approach said completely retracted position despite actuation of said coupling means.
Specification