US2373842A - Portable hand held electric tool - Google Patents

Description

April 17, 1945.

W. G. MITCHELL PORTABLE HAND HELD ELECTRIC TOOL Filed Oct. 16, 1942 3 Sheets-Sheet 1 A 7' 7' OIF/VE Y.

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v O O v O O April 17, 1945- w. G. MITCHELL. 2,373,842

PORTABLE HAND HELD ELECTRIC TOOL Filed Oct. 16, 1942 5 Sheets-Sheet 2 Plll 17, 1945- w. G. MITCHELL 2,373,342

PORTABLE HAND ELD ELECTRIC TooL Filed Oct. 16, 1942 `5 Sheets-Sheet 3 wm am mm a. R. w 0 F. mm. mm mw m H wm WM Y f.. v v EL w E mi. V s ...L L.....1--, E mm .m n w a ax .l ./l. I m M Pw! Nm Mw N\\\m\\w @v QN mv bw l m l l I I l l I I I I TJNT m.- QN mm. )7m QN NN l ww mv A TTO/PNE X Patented Apr. 17, 1945 PORTA-BLE HAND HELD ELECTRIC TOOL Walter George Mitchell, Aurora, Ill., assignor to Independent Pneumatic Tool Company, Chicago. Ill., a corporation of Delaware Application October 16, 1942, Serial No. 462,244

15 Claims.

This invention relates to improvements in portable hand held electric drills and similar tools.

The general purpose and object of my invention is to .provide an electric drill or like tool adapted for industrial uses, but suiiiciently small in size and weight that it may be easily and conveniently held and manipulated in one hand and be continuously used over extended periods in production work especially by female workers without undue fatigue.

A further object of my invention is to provide the tool with a substantially U-shaped strong, but light metal frame rigid at its opposite ends to. support the tool motor and the spindle and the reducing gear drive therebetween whereby relatively light and inexpensive cover and handle members of sheet metal or plastic or other mold- 2 able non-metallic-material may be employed to employed at the opposite ends of the frame to provide the supports for the rear end of the motor shaft and the gear housing, respectively.

A further object of my invention is to provide the releasable connection aforesaid for the stator with the frame in a. form providing for the turning of the stator into either of two rotative positions, one for the release of the stator from the frame, and the other for the support of the stator within the frame.

A further object of my invention is to mount the switch device for the motor within the hollow grip portion of the tool handle independently of the current supply cable for the tool motor and the closure element which carries the cable clamp and closesv the cable receiving opening in the handle to facilitate the` renewal of a cable without removing the' switch or disturbing the assembled relation of the switch within the handle.

A further object of my invention is to ground the motor supporting frame and the gearing through the bracket whichmounts the switch device within the tool handle by providing the bracket at its lower end with a binding screw for the ground lead within the supply cable and connecting the upper end of the bracket to the frame through at least one of the screw members which secure the handle member to the frame at the rear end of the tool, thereby protecting the operator holding and manipulating the tool from shocks due to accidental grounding of the motor current and without requiring a tool housing wholly or partly of an insulating .to lock the trigger block in its depressed or inward position to keep the switch closed when continuous running of the tool motor is desired.

A further object of my invention is to have the bracket lock the closure plate in closing relation in. the opening in the `handle through which the switch device and the bracket are inserted in assembling the tool independently of inserting and mounting the switch device and the bracket in the handle.

A further object of my invention is to provide a screw cap on the front end of a tubular extension on the gear case housing to hold in. place both the bearing for the spindle within said extension and the front cover section of the tool housing over the gear casing.

Other and further objects of my invention will appear from the following specification taken in connection with the accompanying drawings in which* Fig. 1 is a side view of my improved portable hand held electric tool;

Fig. 2 is a top plan view oi the tool with the cove;- and handle sections broken away to show the motor supporting frame;

Fig. 3 is a longitudinal sectional view of the tool to Show its details of construction, parts being shown in elevation and in section, respectively;

Fig. is a. side view of the trigger block removed from the tool and partly broken away and in section, respectively, to show the holding fixture for the plunger lock;

Fig. 11 is a sectional view in respect to the trigger block taken on line I I-H of Fig. 3, the trigger block being shown in its normally out wardly projected position; v

Fig. 12 is a similar sectional view of the same parts showing the plunger lock for the trigger block holding the latter in its depressed position to keep the motor switch closed;

Fig. 13 is a side view of a detail of construction to be later described; and

Fig. 14 is a sectional view showing the cable clamp and, the closure plate for the cable receiving opening in the tool handle, plus a wiring diagram to be hereinafter referred to. y

In the drawings, I have shown a portable hand held electric tool of the pistol grip type having a motor section i, a reducing gear section 2 and a handle section 3. These sections are secured together in the assembled relation shown and contain the operative parts of the machine. In the embodiment shown, the cover elements for these respective sections are comprised of a relatively light and inexpensive plastic material formed to the desired size and shape. The concept here is to replace the presently restricted aluminum casings heretofore employed for these tools with plastic cover and handle sections while reducing the weight of the tool and retaining the full power of the previous tools.

The support for the motor comprises an integral U-shaped skeleton metal frame l having substantially parallel arm portions 5, t and connecting end wall portions l, t at the opposite ends of the frame. The wall portion l is in the form of a cross-web at the rear end of the frame, while the wall portion 8 has a ring formation at the front end of the frame. The ring 8 has a center opening 9 large enough to pass the motor armature or rotor lli, the air circulating fan il, and the armature shaft i2 all as an assembled unit, but not the iield coil and stator assembly i3.v

'I'he stator i3 is releasably mounted within the frame d between the arms 5, t in the manner to be later described'. The ring B is rigidly xed to the outer ends of the frame arms 5, and extends on opposite sides thereof to provide a seat on the front side of the ring for the gear case housing It and a shoulder i5 on the rear sideof the ring for the front end ofthe plastic cover i6 which lits about the frame and the motor as shown in Fig. 3.

'Ihe frame l extends back into the handle section 3 which is made hollow to receive the rear end of the frame and is secured thereto by fastening screws il, il which screws take into tapped openings i8, i8 in the web-wall l of the frame. The handle 3 is secured to the frame i after the cover i6 has been applied over the rear end of the frame and holds the cover against the shoulder l5 as shown in Fig. 3.

'Ihe inner end portions of the frame arms E, are formed to provide diametrically disposed inwardly extending lugs I9, i9 having tapped openings 20, 2@ parallel to the arms. These openings 20 receive the long fastening screws 2 i, 2| which secure the stator i3 within the frame d. The lugsy i 9 also provide supports for the cartridge type brush units 22, 22 for the tool motor, the carbon rods of the brush units being spring urged against the commutator 23 of the motor as indicated in Fig. 3. Set screws 24, 24 secure the 'the stator plates di.

brush units 22 in the lugs i8, each of the latter having a brush receiving opening 25, as shown in Fig. 7. The tapped openings for the screws 2| and 2d intersect the brush receiving openings 25 from the opposite sides thereof and being in alinement are made in a single drilling operation. The headed ends of the screws 2l engage a ring element 2t which by sleeves 27, 27 on the screws space the ring with respect to the fan il to provide the rear wall of the fan chamber and deflect the incoming air to the center intake of the fan. 'Ihe bane 26 lts against the inner surface of the motor cover it on opposite sides of the frame arms E, for this purpose as shown in Fig. 4. The vsleeves 2l also space the baie plate 2a suiciently forward of the motor i@ to provide a space for the front loops 2d of the stator wind ing 2S as shown in Fig. 2. The handle section 3 being hollow takes care of the rear loops 3d. The stator plates are slotted as at Si in Fig. 4 to mount the winding 29.

The ball bearing unit 32 for the rear end of the armature shaft i2 vis mounted in a recess @t in the web-wall l of the frame d. The bearing unit 3d for the front end of the shaft i2 is mounted in a recess 35 in the gear case housing id.

The fan H is splined on the front end portion of the shaft i2 between the ring members d and 26 which provide the front and rear walls of the -fan chamber. Air intake openings 3S for the fan are in the handle section 3, while the air discharge openings 3l for the fan are in the forward edge of the motor cover le in the form of slots at the periphery of the fan as shown in Fig. 1. The cover section l has inside ribs ida, ita which t against the adjacent side portions of the staton iii to hold it in place and provide channels 33, 38 therebetween for the Iiow of cooling air over the outer side of the stator. The path of the air ow is from the rear to the front of the motor as indicated by the arrows in Figs. 2 and 6.

The releasable mounting for the stator i 3 within the frame 4i comprises arcuate surfaces 39, 39 on the inner sides of the frame arms E, t on the same radius as the outer curved edges et, d@ of I'he side portions of the stator plates are cut away, so to speak, to provide iiat surfaces Q2, d2 which make the stator cross- Wise less than its full diameter. With at sides d2, the stator i3 may be turned from a position supported by the frame arms as shown in Figs. 3 and 4 to a position with the flat sides opposite to said frame arms. In the latter position, as indicated by the broken line representation in Fig. 8, the stator is free of the arms and may be shifted laterally into and out of the frame d through either of the open sides thereof in assembling and disassembling the stator with respect to the frame. After the stator has been inserted into the frame, the stator is turned to bring its curved edges iii into engagement with the complementary edges 39 of the frame arms and then the screws 2i are applied to secure the stator within the frame. Removing the screws and turning the stator to present its at sides d2 opposite to the frame arms provides for the lateral shifting of the stator out of the frame. With this manner of mounting the opposite end portions of the frame d `may have the rigid connections l and 8 to support the rear bearing for the motor and the gear housing, respectively.

As shown in Fig. 4, the frame arms 5, 6 are channeled as at d3, d3 between the inner curved surfaces 3s to reduce the amount of machining and grinding required in making the curved surfaces on the arms. reducing the weight of the frame and allow the The channels 43 also aid in cooling air to flow between the parts. The baille except at its center opening.

.- T'he` gearr case housing I4 is a metal casting in one piece to eliminate the need for'a separate end plate between the motor and the gear housing as ini-the previous tools. The one-piece gear housing I4 also permits the front and rear bear- .'ings therein for the spindle and intermediate shafts of thel vtool drive to be made in perfect alignment Ain single drilling operations. This I f feature is'described and claimed in my co-pendf ing application Serial No. 475,367, led Feb. 10,

'The housing I4 is formed to provide a hollow body portion 44 providing a chamber 45 to house the gears which drive the tool spindle 46 ,from the. armature shaft I2. The rear end wall 41 of the housing I4 iit/s against the front face of thefframe ring 8 and is secured thereto by screws. one of which is shown at 48 in Fig. 6. The ring l8 has tapped openings 49, 45 for these screws as shown in Fig. 9. The connection is made before the stator cover IB is appliedv over the frame 4 and rbefore the handle section 3 is secured to the frame by the screws I1. The screws 46, as

indicated in Fig. 6, are applied from the rear. side of the ring so that the front side of the ring may provide a'. flat seat for the plastic cover sec-l tionv ilfor the-gear housing I4.

The gear housing wall 41 conforms to the size l and contour of the ring 8 and has its center portion' fitting within the center opening 9 of the ring to interfit and align the parts when assem-v application. The shaft 53 is mounted in ball bearing units as shown in said co-pending application. The gear 52 rotates'a gear pinion 54 on the shaft 53 and said pinion 54 meshes with and drives a gear wheel 55 fixed on the tool spindle 46 asv shown in Fig. 5. The front end of the housing I4 has a tubular extension 56 through which the spindle 46 extends and is externally screw y threaded to receive a cap-nut 51.

Mounted in the end wall 41 is a. roller bearing 5 8 for the inner end of the spindle shaft 45, the front bearing unit 69 for said. `spindle being 'mounted within the tubular projection 55. The

screw cap 51 `engages said front bearing 59 for holding it in place. The spindle 46 extends out of the housing I4 at its front en d beyondv the screw cap 51 and there mounts a chuck Sil.

The outer cover 50 for the gear case housing I4 is made of plastic, as heretofore mentioned. and is clamped against the gear case wall 41 by the screw cap 51. This is provided by having the front end of the cover overlapped by the screw cap and the rear end of the cover abutting against the front face of the wall 41 as shown. At this point, the cover 50 has an interior wall portion SI seating against the wall 41 beneath a centering rib 82.'

The body portion 44 is provided with side openings 63, B4as shown in Fig. ,5, whereby the gears may be inserted 'within the housing and be removed therefrom. This feature is also claimed in my co-pending application as aforesaid. A shield element, not shown herein, may be fitted over'the body portion 44 o' the housing I4 to cover the side openings 63, 64 against the escape'of grease packed within the housing chamber for the gears. This feature of the shield is shown and claimed in my co-pending application SerialNo. 475,367.v

The handle section 3 closes the rear end of the tool and is provided with a depending hollow pistol grip portion 65. A swi-tch device 66 is mounted within the hollow pistol grip 65 by a bracket 61. The latter is in the form of a flat metal strip having its upper end engaged by the lower fastening screw I1 as shown in Fig. 3. Thev lower end of the strip 61 is provided with a folded over angular portion 68 to support a plastic closure 69 for the opening 10 in the lower or butt end of the pistol grip 65. A screw 1I secures the cover 59 to the bracket end G8 and the latter carries a binding screw 12 for the ground lead 13 in tlie current supply cable 14 for the tool motor.

The bracket strip 61 seats in a channel 15 in the rear wall ofthe handle grip 65 as shown in Fig.' 2. The channel extends the full length of the grip 'and the strip is held therein by the switch device 56 which overlaps the strip and the channel.' The switch device is secured to this part of the strip and the grip 65 by a screw and boss to be presently described. The switch device carries on its iront side af superstructure 11 equipped with an operating lever 18 on a fulcrum 19. The lever is of the bell-crank type having one arm co-acting with the spring action within the switch device to open the switch when the lever swings outwardly and toclose the switch when the lever is forced inwardly. This accords to the conventional switch action of the `type depicted, the switch unit with the lever 18 Y block 8l is slidably mounted in a rectangular opening 02 in the tool handle 65 iust below the frame 4 and the cover section I6 so that the trigger block 8l may be conveniently and easily engaged by theiinger of the operators hand grasping the tool handle G5. lThe trigger block 8| has the same shape as the opening 82 in which it is mounted and is normally urged outwardly by the switch spring 80 pressing the outer end of the lever 18 against the inner end of the trigger block. The latter has a stop lug 83 at its upper inner end to engage the handle section to limit the outward projection of the trigger block by the spring. The frontend of the trigger block is curved to t the operator's finger cngaging the same.

operating current to the tool motor. Releasing the trigger block causes the spring -to automatically open the switch and project the trigger block outwardly to its normal position as shown in Figs. 4 and 11.

The inner end of the trigger block 5I is'beveled inwardly and downwardly so that the lever 18 may ride on the trigger block in the operation thereof. The trigger block at this point carries a metal wear plate 84 for contact with the lever A spring 8U forming part of the switch Pressing the trigger block BI inwardly .closes the switch 56 and supplies the 78, the trigger block being made of a plastic material similar to that of the cover and handle sections of the tool. The wear plate I6 constitutes a part of a metal xture applied to the trigger block as shown in Figs. 10 to 12. As there illustrated, the trigger block is made hollow providing a chamber 85 opening through the rear end of the block to receive the aforesaid metal fixture. The latter is generally U-shaped in form having its arm portions 8b, 86 extending into the chamber 85 and engaging against the upper and the lower wall portions 8l, el thereof with a slight spring tension, the fixture being a sheet metal stamping. 'Ihe arm portions Se may be provided with struck-out tangs 8B, B8 facing the open end of the chamber 85 for holding the nxture therein. The wear plate 85 has end extensions t9, S9 to overlap the upper and lower end portions of the block, said extensions et being struck-out from the arms portions tt as shown. These extensions 69 continue the wear plate Sli the full height of the block, the wear plate being an integral part of the xture.

Normally, the trigger block 6| is projected outwardly by the switch spring dii. To releasably lock the trigger block in its inwardly depressed position to keep the switch device et closed as required for a continuous running of the tool motor, I provide a locking plunger e@ at one side of the block and slidably mounted in a bushing 9| fitted within an opening a2 in the adjacent portion of the handle grip t5. A coiled spring 93 about the plunger 98 normally urges it outwardly or into its release position The spring S3 seats at its inner end against the bushing at its crosswall 96 and at its outer end against a push button 95 carried by the plunger 96 at its outer end.

The plunger de is provided at its inner end with a nat, circular disc-like head 9S which takes into a longitudinal groove 9i in the adjacent side of the trigger block Bi. The inner end of this groove is semicircular as at Se, the reminder 99 of the circular form being completed -by a flangelike extension It@ on the ixture above referred to and overlying the front side of the groove el from the wear plate 8f3. The upper and lower edges of the groove 81 are channeled as at mi to seat the ange |90 in outwardly spaced relation to the bottom of the groove as shown in Fig. 10. This allows the head se of the plunger 9@ to enter the groove and engage behind the ange |09 at the circular opening which the flange and groove provide for the circular head 9B. This can occur when the parts are in register, the plunger 9U being pressed into the groove and when released will engage behind the ange it@ to lock the plunger in its depressed position as shown in Fig. 12. The switch spring te presses the ilange le@ against the stem of the plunger 90 and the switch 66 is held closed until the trigger block 8| is again depressed to free the head 96 of the plunger from the iiange, whereupon the plunger spring 93 projects the plunger away from the ange and on release of the trigger 'block 8| the switch spring 8e returns the block to its outwardly projected position as shown in Fig. 11. The spring e3 holds the head 95 of the plunger Sli'against the bushing wall 96 and the plunger does not ride on the fixture flange in the inward and outward movement of the trigger block in closing and opening the switch t8.

In assembling the tool and more particularly connecting the motor and switch units in the supply circuit, the procedure is substantially as follows: The motor and the gear case sections are secured together in the assembled relation shown in Fig. 3. Before the handle section 3 is secured in place against the rear end of the motor supporting frame d, the bracket strip 61 and the switch unit t8 are inserted into the hollow grip portion of the handle 3 through the opening 'le at its lower or butt end. The bracket is positioned with its upper end to be engaged by the lower of the handle screws Il and its lower end et at the opening 10. The switch is positioned on the bracket with the lever l5 extending towards the opening lil and the boss |02 on the rear side of the switch case in an aperture in the bracket to seat in a recess |03 in the rear wall of the handle grip 65 when these parts reach their iinal positions as shown in Fig. 3. Then a screw itt is inserted through the handle and engaged with the boss, which is tapped, to secure the switch and the strip in the handle. Before the switch unit is inserted in the handle, the wires H35, for the upper terminals for the switch are connected thereto. The trigger block el is inserted into the slot 82 from within `the handle member before the .switch and the bracket are applied and the stop 83 on the trigger block prevents the latter from dropping out of the handle.

Next, the supply cable it is inserted through an opening in coverplate 69 while removed from the tool and secured to the plate by the cable clamp comprising a split band |91 and its screw me. The band embraces an anchoring wall |09 integral with the plate and conforming to about half of the cable opening to expose the cable to be clamped by the band. Then the supply wires ilii, im carried by the cable 'l areonnected with the lower terminals of the switch unit 66 within the handle and the ground Wire 13 of the cable is connected to the bracket 6l by its terminal screw l2. The cover plate 69 carrying the cable 'it is now inserted into closing relation in the handle opening 'l independently of the switch.

It will be noted from Fig. 14 that the handle section 85 about the opening 'l0 opposite the lower end 66 of the bracket strip -61 has an arcuate groove having a horizontal bottom wall H2. The portion of the cover plate 69 has a rib projection H3 complementary to the groove so that the parts may intert when engaged. This is done by disposing the plate es on an angle and inserting the plate with a tilting action into the opening lt, rst engagng its rib H3 into groove and then swinging the plate into closed relation in the opening l0, its free edge H being inclined to engage a complementary edge of the opening 70 as indicated in Fig. 14. Then the screw 7| .is applied and the cover 69 is locked in closed position by the bracket 61. It will be noted that the closure -69 has a recess on its inner side to accommodate the head of the binding screw 72.

Lastly, the handle 3 is brought sumciently close to the rear end of the tool for a connection to be made between the switch wires |05, |05 and the motor brush leads |06, |06 as shown in Fig. 14. The handle section 3 may now be secured to the motor frame t by the screws I1, i1. To accommodate the frame arms 5, 6, the baille plate 26 has recesses 2Gb, 2Gb on opposite sides of its lugs 26a, 28a, as shown in Fig. 4.

With the gear housing I4 in the form of a onepiece casting and secured to the front end of the motor supporting frame 4 by the screws e8 as shown herein, the frame member 4 not only provides a support for the motor Hl and its stator 13, but supports the gear housing Il and its gear train and the tool spindle 48, independently of the cover and handle sections I S, 50 and 3, respectively, of the tool housing as shown in Fig. 3. Hence, these cover and handle sections may be made in separable form for individual handling in assembling and disassembling of the tool and when opening thetool for inspection of its motor and gear reducing and spindle sections without disturbing their connected operative relation or the support thereof by the frame 4 as will be apparent from Figs. l to 4. It will be particularly noted from these figures that the cover sections i6 and 50 for the motor and the reducing gear assemblies, respectively, are each made in onepiece, open ended, substantially 'cylindric or tubular form to completely and continuously surround their respective tool sections when applied thereto and are slidable on and o the associated ends of the frame in applying the cover sections to and removing them from the frame. The advantage of this arrangement is that the tool may be readily and easily opened for inspection by merely removing the cap-nut 5T at the front end of the tool and the handle 3 at its rear end whereupon the cover sections are slidable oi the frame 4 to expose the tool mechanism without taking the cover and handle sections apart or disturbing the mounting of the motor and the reducing gear or the spindle on the supporting frame 4. To provide the sliding connection for the cover section I6 on the frame I, said cover section is provided with inside grooves or channels l6c, lBc to receive the frame arms 5, 6 as shown in Fig. 4. This arrangement provides intertting parts on the frame and the cover section I6 for their relative sliding movement and to hold the cover in nonrotatable connection with the frame.

The tool shown and described has the power factor required for industrial uses, is light in weight for ease in handling and balance and is small in size for convenient grasping and manipulation, all contributing to the effectiveness of the tool for production'work over extended periods. The details of construction and arrangement of parts shown and described may be variously changed and modied without departing from the spirit and scope of my invention, except as pointed out in the appended claims.

I claim as my invention:

1. A portable hand held electric tool having a rotatable spindle, a U-shaped metal frame within the tool having substantially parallel arm portions extending lengthwise of the tool and metal end wall portions rigidly connecting the arm portions at the front and rear ends of the frame, an electric motor supported within .the frame by the arm portions and having an armature shaft journaled in the rear end wall of the frame and havi ing gear teeth at the front end of the frame, a

gear train connecting the gear teeth with the spindle for driving the same, a gear casing about the gear train and secured to and supported by the front end wall of the frame and providing a support for the spindle, a housing for the tool having a cover section about the gear case and the frame and a handle section at the rear end of the tool, said handle and cover sections being supported by the frame and comprised of a relatively thin material, and a switch device for the motor carried by and operable from the exterior of the handle.

2. A portable hand held electric tool having a rotatable spindle and an electric motor for driving the same, a U-shaped metal trame within the tool having substantiallyA parallel arm portions providing a support for the motor and the spindle.

a housing for the tool having a handle section l fsecured to the frame at the rear end of the tool and a cover section held by the handle section about the motor and the frame, a fan element 1ocated within the cover section and driven by the' motor for cooling the same, said fan havingv aV center intake and a peripheral discharge, a baule plate supported Within the cover section at one side of the fan and engaging the yinner surface of the cover on opposite sides of the frame arms for deilecting the incoming air to the center intakeI of the fan, said baffle plate having an interlocked connection with the frame arms, and a switch device for the motor carried by and operable Vfrom l the exterior of the handle.

3. A portable hand held electric tool having an j' I electric motor, a rotatable spindle, a Uf-shaped' metal frame within the tool providing a support dle section being secured to the frame at the lrear end of the tool. and a clamp element mounted on the tubular extension of the drive casing about the spindle and engaging the front cover for holding the same about the casing.

4. A portable hand held 'electric tool having a l rotatable spindle andan electric motor for driving the same, a metal frame within the tool pro viding a support for the motor and the spindle, a housing for the tool comprising a handle sec; tion at the rear end of the tool and a cover section surrounding the motor andthe frame, fastening members for securing the handle section tc the rear end of the frame, said handle having a depending hollow pistol grip portion extending below the cover section and the frame, and a switch device and a supporting bracket` therefor secured within the grip portion of the handle, said switch device being operable from the ex. terior of the handle for controlling the operation of the motor, said bracket being connected to the frame by oneiof the handle fastening members and providing a ground connection for the motor.

5. A portable hand held' electric tool having a rotatable spindle and an electric motor for drivn ing the same, a metal frame within the tool providing a support for the motor and the spindle, a housing for the tool comprising a cover section surrounding the motor and the frame, and afi handle section at the rear end of the tool, said handle section being secured to the frame. andhaving a hollow grip portion at the `rearend thereof, a manually operable switch device for thefi motor and a supporting bracket therefor securedv Y j within the grip portion of the handle vand inserted therein through an opening in the handle, said bracket being connected ati-its upper end with lower end of the bracket independently of inserting and securing the switch device anjd the bracket within the handle. Y

6. A portable hand held electric tool having a rotatable spindle and an electric motor for driving the same, a metal frame within the tool pro viding a support for the motor and the spindle, a housing for the tool comprising a handle section at the rear end of the tool and a cover section surrounding the motor and the frame, said handle being secured to the frame and having a dependinghollow pistol grip portion at the rear end thereof, a manually operable switch device for the motor and a supporting bracket therefor secured within the hollow grip portion of the handle and insertible therein through an opening at the butt end of the handle, said bracket comprising a metal strip seated within a channel in the grip portion of the handle and connected at its upper end to the frame and having a ground providing flange portion at its lower end at said opening, and a closure plate for said opening carrying a supply cable for the motor and locked in closing relation in said opening by the ianged end oi' the bracket.

7. In a portable hand held power operated tool, a driving motor therefor, a substantially U- shaped frame having longitudinally extending arm portions providing a support for the motor within the tool, a housing having a cover section about the motor and the frame and a handle section at the rear end of the frame and secured thereto for holding the cover section on the frame, said cover section being in one-piece, open ended, substantially cylindric form to completely and continuously surround the motor and the frame and slidable thereon over the rear end of the frame in applying the cover section to and removing it from the frame, and interiltting means on the cover and the frame arms for slidably and non-rotatably supporting the cover section on the frame.

8. In a portable hand held power operated tool, a driving motor therefor, a substantially U= shaped metal frame having longitudinally extending arm portions providing a support for the motor within the tool, a housing for the tool having a cover section about the motor and the frame and a handle section at and secured to the rear end of the trame for holding the cover section thereon, said cover section being in onepiece. open ended, substantially cylindric form to completely and continuously surround the motor and the frame and slidable thereon over the rear end of the frame in applying the cover section to and removing it from the frame, said cover section having channels therein to receive the frame arms to slidably and non-rotatably mount the cover on the frame.

9. In a portable hand held power actuated tool, a motor and a spindle driven thereby, a frame supporting the motor and the spindle and the driving connection therebetween, a houseing for the tool supported by the frame and having separable motor and spindle enclosing sections and a handle section at the rear end oi' the tool, said cover sections being in one-piece, open ended, substantially cylindric form to completely and continuously surround the motor and the spindle sections of the tool and slidable over the assoelated ends of the frame in applying the cover sections to and removing them from the frame, said handle engaging the motor enclosing section for holding the same on the frame. means for releasably securing the spindle enclosing and the handle sections to the opposite ends of the frame whereby the cover sections may be individually applied to and removed from the frame without envases disturbing the mounting o! the motor and spindle and the drive therebetween on the frame.

. 10. A portable hand held electric tool having a rotatable spindle, a metal trame having substan tlally parallel arm portions extending lengthwise of the tool and metal end wall portions rigidly connecting the arm portions at the front and the rear ends of the frame, a gear frame secured to thev metal frame at its front end and having an end wall portion extending between said arm portions, an electric motor supported within the metal frame by the arm portions thereof and having an armature shaft journaled at its opposite ends in the respective end wall portions ofthe gear frame and at the rear end of the metal trame, said gear frame supporting the spindle and a gear drive from the shaft to the spindle, cover and handle sections for the tool oi a relatively lightplastic material, said cover section being in one-piece, open ended, tubular form to completely and continuously surround the motor and the metal frame and slidable on and oil the arm portions thereof over one end of the metal frame in applying the cover section to and removing the latter from said metal frame, said handle section being secured to the metal frame and holding the cover section thereon, and a switch device for the motor carried by and operable from the exterior of the handle.

ll. A portable hand held electric tool having a rotatable spindle, a metal fra'me having substantially parallel arm portions extending lengthwise of the tool and metal end wall portions rigidly connecting the arm portions at the front and the rear ends of the frame, a gearirame secured to the front end of the metal frame and having an end wall portion extending between said arm portions, an electric motor supported within the metal frame by the arm portions thereof and having an armatureshaft journaled at its opposite ends in the respective end wall portions oi the gear frame and at the rear end of the metal frame, said gear frame supporting the spindle and a gear drive from the shaft to the spindle, separable cover and handle sections for the tool of relatively light plastic material, said cover section being in one-piece, open ended, tubular form to continuously and completely surround the motor and the metal frame and slidable on and voil the arm portions thereof over the rear end of the metal frame in applying the cover section to and removing the latter from said metal frame, said handle section being secured to the rear end wall of the metal frame in closing relation to the cover section and engaging the same for holding the cover section on the metal frame, and a switch device for the motor carried by and operable from said handle.

12. A portable hand held electric tool having a rotatable spindle, a metal frame having substantially parallel arm portions extending lengthwise of the tool and metal end wall portions rigidly connecting the arm portions at the front and the rear ends of the frame, a gear frame secured to the iront end of the metal frame and having an end wall portion extending between said arm portions, an electric motor supported within the metal frame by the arm portions thereof and having an armature shaft journaled at its opposite ends in the respective end wall portions of the gear frame and at the rear end of the metal frame, said gear frame supporting the spindle and a gear drive from the shaft to the spindle, cover and handle sections for the tool of a relatively light plastic material, said cover sectionV being in 2,373,842 'one-piece, open ended, tubular form to completely and continuously surround the motor and the metal frame and slidable on and oii` the arm por.. tions over the rear end of the metal frame in applying the cover section to and removing the latter from the metal frame, said handle section being secured to the rear end of the metal frame and holding the cover section against a stop at the front end of the metal frame. and a switch device for the motor carried by and operable from said handle.

I13. A portable hand held electric tool having a rotatable spindle, a substantially U-shaped metal frame having substantially parallel arm portions extending lengthwise of the tool and metal end wall portions rigidly connecting the arm portions at the front and the rear ends of the frame, a one-piece gear frame having an end wall portion extending between the arm portions of the U-shaped frame and secured to and fitting against the iront end wall portion of the latter, an electric motor supported within the U-shaped frame by the arm portions thereof and having an armature shaft journaled at its opposite ends in the respective end wall portions of the gear frame and at the rear end of the U-shaped frame, said gear frame supporting the spindle and a gear drive from the shaft to the spindle, a housing for the tool having .cover and handle sections of a relatively light material, said cover section being in one-piece, open ended, tubular form to completely and continuously surround the motor and the U-shaped frame and slidable on and oir the arm portions overthe rear end of theU-sliaped frame in applying the cover section to and removing the latter trom said U-shaped frame, said handle section being secured to the rear end wall of said U-shaped frame and holding the cover section about the same, and a switch device for the motor carried by and operable from the handle.

14. A portable hand held electric tool having a supporting frame provided with substantially parallel, rigid, arm portions extending lengthwise of the tool and rigid endy wall portions connecting the arm portions at the front and the rear ends of the frame, a gear frame secured to the supporting frame at its front end having an end wall portion extending between said arm portions, an electric motor having a stator provided with a turnable connection with the frame arms pro.

vding for the release of the stator in one rotative position and a support for the stator in another rotative position thereof, an armature shaft for the motor journalled in the said end Wall portion of the gear frame and at the rear end of the supporting frame, respectively, a rotary spindle supported by the gear frame, a driving connection from theshaft to the spindle, said supporting frame being open along at least one side where by the stator when turned to its release position is shiftable laterally into and out of the frame in assembling and disassembling the stator with respect to the frame, and handle and cover sections for the tool disposed on the supporting trame.

15. A portable hand held electric tool as deined -in claim 14 characterized by the fact that the front end wall portion of the supporting frame is provided with an opening of suilicient size to pass the armature and its shaft endwise out of the frame to release the stator for its shifting movement with respect to the frame in an assembling and disassembling operation.

WALTER GEORGE MITCHELL.

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