Portable electric grinder
First Claim
1. A portable power tool, particularly an electric grinder or sander, comprising a rotary tool supporting spindle including a hollow shaft and an inner shaft in said hollow shaft;
- drive means for one of said shafts;
tool clamping means including first and second clamping portions respectively mounted on said inner and hollow shafts and being movable apart, to thereby release a tool which is clamped therebetween, in response to rotation of said shafts relative to each other; and
means for arresting the other of said shafts so as to effect a movement of said clamping portions apart and to thus effect a release of the tool between such clamping portions by rotating the one shaft while the other shaft is held against rotation, said arresting means comprising an arresting member which is movable by hand to a position of engagment with said other shaft and means for yieldably biasing said arresting member away from said position, said other shaft including a main portion and an annular portion separably affixed to said main portion and having a plurality of recesses which are angularly offset realtive to each other in the circumferential direction of said other shaft, said arresting member having a portion which is received in one of said recesses in the position of engagement of said arresting member with said other shaft.
1 Assignment
0 Petitions
Accused Products
Abstract
A portable electric grinder wherein the grinding wheel is held against rotation relative to the spindle by two annular clamping rings. The spindle has a motor-driven hollow outer shaft and an inner shaft which is installed in the outer shaft and can be held against rotation with the outer shaft by a manually depressible arresting member. One of the clamping rings rotates with the hollow shaft and the other clamping ring mates with the inner shaft. When the inner shaft is held against rotation and the motor is started for a short interval of time, the hollow shaft rotates the one clamping ring which rotates the grinding wheel and the other clamping ring by friction so that the grip of the clamping rings upon the grinding wheel is loosened and the grinding wheel can be fully separated from the spindle by completing the unscrewing of the other clamping ring from the inner shaft. The motor drives the hollow shaft through the medium of a step-down transmission.
41 Citations
14 Claims
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1. A portable power tool, particularly an electric grinder or sander, comprising a rotary tool supporting spindle including a hollow shaft and an inner shaft in said hollow shaft;
- drive means for one of said shafts;
tool clamping means including first and second clamping portions respectively mounted on said inner and hollow shafts and being movable apart, to thereby release a tool which is clamped therebetween, in response to rotation of said shafts relative to each other; and
means for arresting the other of said shafts so as to effect a movement of said clamping portions apart and to thus effect a release of the tool between such clamping portions by rotating the one shaft while the other shaft is held against rotation, said arresting means comprising an arresting member which is movable by hand to a position of engagment with said other shaft and means for yieldably biasing said arresting member away from said position, said other shaft including a main portion and an annular portion separably affixed to said main portion and having a plurality of recesses which are angularly offset realtive to each other in the circumferential direction of said other shaft, said arresting member having a portion which is received in one of said recesses in the position of engagement of said arresting member with said other shaft. - View Dependent Claims (2, 3, 4, 5)
- drive means for one of said shafts;
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6. A portable power tool, particularly an electric grinder or sander, comprising a rotary tool supporting spindle including a hollow shaft and an inner shaft in said hollow shaft;
- drive means for one of said shafts, said drive means comprising an electric motor;
tool clamping means including first and second clamping poritons respectively mounted on said inner and hollow shafts and being movable apart, to therby release a tool which is clamped therebetween, in response to rotation of said shafts relative to each other;
means for arresting the other of said shafts so as to effect a movement of said clamping portions apart and to thus effect a release of the tool between such clamping portions by rotating the one shaft while the other shaft is held against rotation; and
operating means actuatable to start said motor for a selected interval of time for the purpose of rotating said one shaft relative to said other shaft so as to release the tool between said clamping portions. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
- drive means for one of said shafts, said drive means comprising an electric motor;
Specification