Operation safety device for a portable power tool
First Claim
Patent Images
1. A cutting instrument comprising a power-driven blade;
- and a movable blade carrier for moving said blade along an advancement stroke in order to approach and cut through a workpiece;
said blade carrier comprising a first portion having a first guard disposed around said blade, and a second portion having a second guard for said blade;
said second portion being mounted for movement relative to said first portion during said advancement stroke; and
an electrical safety switch means having a safety position for preventing said blade from rotating at its cutting speed, and an operating position permitting said blade to rotate at its cutting speed;
said safety switch means being normally disposed in its safety position when said blade is out of contact with a workpiece during said advancement stroke, said safety switch means arranged to be moved to its operating position in response to movement of said second portion relative to said first portion during said advancement stroke, said safety switch means including first and second switch parts connected to said first and second portions, respectively, said second switch part being fixedly joined to said second portion for movement therewith relative to said first switch part in a first direction into said operating position and in a second direction into said safety position, wherein said second switch part moves along a travel path relative to said first switch part and makes electrical contact with said first switch part during only a portion of said travel path.
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Accused Products
Abstract
A power miter box includes a power driven blade which is lowered onto a workpiece. A main switch must be actuated manually by an operator to drive the blade. A separate safety switch operates to prevent the blade from being driven until it has been lowered onto the workpiece. The safety switch is operated by relative movement occurring between two guard members which encompass the blade.
125 Citations
6 Claims
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1. A cutting instrument comprising a power-driven blade;
- and a movable blade carrier for moving said blade along an advancement stroke in order to approach and cut through a workpiece;
said blade carrier comprising a first portion having a first guard disposed around said blade, and a second portion having a second guard for said blade;
said second portion being mounted for movement relative to said first portion during said advancement stroke; and
an electrical safety switch means having a safety position for preventing said blade from rotating at its cutting speed, and an operating position permitting said blade to rotate at its cutting speed;
said safety switch means being normally disposed in its safety position when said blade is out of contact with a workpiece during said advancement stroke, said safety switch means arranged to be moved to its operating position in response to movement of said second portion relative to said first portion during said advancement stroke, said safety switch means including first and second switch parts connected to said first and second portions, respectively, said second switch part being fixedly joined to said second portion for movement therewith relative to said first switch part in a first direction into said operating position and in a second direction into said safety position, wherein said second switch part moves along a travel path relative to said first switch part and makes electrical contact with said first switch part during only a portion of said travel path. - View Dependent Claims (2, 3, 4, 5, 6)
- and a movable blade carrier for moving said blade along an advancement stroke in order to approach and cut through a workpiece;
Specification