Double insulated hand tool

• US 3,344,291 A
• Filed: 11/23/1964
• Issued: 09/26/1967
• Est. Priority Date: 11/23/1964
• Status: Expired due to Term

• Current Assignee: Leonard C. Pratt
• Original Assignee: Leonard C. Pratt
• Inventors: Pratt, Leonard C.
• Application Number:
  US04/413,272
• Time in Patent Office: 1,037 Days
• US Class Current: 310/50
• CPC Class Codes: H02K 7/145 Hand-held machine tool

Claims

1. IN AN ELECTRICALLY POWERED HAND TOOL, THE COMBINATION COMPRISING:

A HOUSING;

A SHAFT ROTATABLY MOUNTED WITHIN SAID HOUSING;

AN ARMATURE CARRIED BY SAID SHAFT SUCH THAT A PORTION OF SAID SHAFT PROJECTS FROM SAID ARMATURE;

A COMMUTATOR CARRIED BY SAID SHAFT AND OPERATIVELY CONNECTED TO SAID ARMATURE;

COMMUTATOR BRUSH MEANS DISPOSED WITHIN SAID HOUSING AND OPERATIVELY ASSOCIATED WITH SAID COMMUTATOR;

A FIELD STRUCTURE INCLUDING A FIELD CORE AND ASSOCIATED FIELD COIL DISPOSED WITHIN SAID HOUSING AND OPERATIVELY CONNECTED TO SAID ARMATURE;

AND MEANS UPON SAID SHAFT FOR INSULATING SAID SHAFT;

SAID SHAFT INSULATING MEANS COMPRISING A COATING OF ALUMINUM OXIDE PROVIDED ON SAID SHAFT THROUGHOUT THE LENGTH OF THE PORTION OF SAID SHAFT COEXTENSIVE WITH SAID ARMATURE;

AND A PAPER SLEEVE OVERLYING THE ALUMINUM OXIDE ON THE PORTION OF SAID SHAFT COEXTENSIVE WITH THE END WINDINGS OF THE ARMATURE BUT EXTERNAL OF THE CONNECTION OF THE COMMUTATOR WITH SAID SHAFT.