GB578755A - Improvements in or relating to portable hand held electrically driven tools - Google Patents

Abstract

578,755. Dynamo-electric machines. INDEPENDENT PNEUMATIC TOOL CO. Nov. 17, 1943, No. 19195. Convention date, Oct. 16, 1942. [Class 35] [Also in Groups XXII and XXXVII] A portable electric tool such as a drill has the motor enclosed in a substantially U-shape frame ; the housing of the tool having a cover section about the motor held in place by a rear handle section mounting the switch. Reduction gearing for the spindle as described in Specification 572,046, [Group XXII], is mounted on a front section of the housing held in place by a screw cap. The motor frame has arms 5, 6 springing from a base 7 and stayed at the other end by an annular flange 8 against which the cover section 16 of plastic material is held by the plastic handle section 3 secured to the base 7 by screws 17. The stator 41, Fig. 8 can be inserted into the frame laterally when in the position shown in dotted lines. When in place it is rotated through 90 degrees and secured by screws 21. Brush holders 22 are secured in bores 25 in the frame by screws 24. The forward end of the stator carries a baffle plate 26 having lugs 26a closing lightening and cooling channels 43 in the arms 5, 6 and ensuring that all cooling air passes to the centre of the fan 11 through the opening 26c. The rear ball bearing for the armature spindle is mounted in a recess 33 in the base 7 and the front bearing is carried by the housing of the reduction gearing, The handle contains a switch 66 mounted on a bracket strip 67 secured in a channel in the handle by the lower screw 17. The switch casing has a boss 102 projecting through a hole in the strip for securing by a screw 104. A spring 80 maintains the switch open except when closed by pressing in a trigger piece 81 sliding in a slot in the handle as limited by a lug 83. For continuous running a headed spring stud 96 is pressed through a hole formed in part by the end of recess 97 in the trigger and in part by a part 100 of a metal insert 84, 86 held in the hollow trigger by spring tongues 88. The end of the handle is closed by a plate 69 engaging a groove 112 on one side and secured by a screw 71 in the strip 67, on the other. The motor frame &c. is earthed by a connection at 72 to the earthing wire of the cable 74 held in place by a clamp 107. The power leads are wired as shown in Fig. 14 to the switch 66 which in turn is wired at 105 to connectors for the brush leads. Openings in the handle admit air near the commutator and discharge it through slots 37, Fig. 6 in the cover 16 near the periphery of the fan 11.