US1596013A - Control mechanism for electric tools - Google Patents

Description

Aug. 17 1926.

. J. J. GEBHARDT CONTROL uzcamlsm FOR ELECTRIC TOOLS Filed A til 13, 923 /326 p Patented Aug. 17, 1926.

4 umfrnn stratus nuns-1f enmmn'r, orcmmmmnrmoxs; YASSIGNOK m'wonncxmznc'rnm moon" CORPORATION, or-cnnmeo; nznmors; mconronmxon'orummoxs;

com-non MECHANISM FOR mic: moons:

mum meduwuaia 1m. 'smmm; .mpsoi Theinvention pertains to electric tools such as drills, hammers,- etc. and hasforits aim t Q PIOVlSlOIlOf a controlling: mechanism* of advantageous:

g: charaoten for toolsoff this typu Portable electrio tools new oommonlysinv use are uipped with wswitch mechanism for oontro ling the operation, which requires.

a manual operation bothvfovwtting the tool 10' inc ation and for stopping-it: Because of t distinct manual operatiom required? for stopping the tool; the new frecgzently negleots tmcut of! theourrent when. lays the tool aside so thatdtcontinues to operate w idly. This-results in unnecessary wearand tea'r'and also presents 1 source of danger:

to the operator and his" fellow workmen. Moreover,- mrder some oomlitions it' is very necessary thmt the tool hm brought to: an 20' ihstknt stop, but inthe umeof the tools in common use, as above mentimedl-inmudl as the stoppage requires= the distimt. operation of the switch, considerable: time may eltppebefore it is possible to -bring;the=tool 88' to rest, and in this-time serious-injury may result to the operator as well ias to 'the tool. Toovercome the disadvantages resulting fiom the common type'orf control n'ism; itis desirable to employ w switch 80 which automatically breaksth e circuit when the operator releases the switch operating: member. In some instlmms; However, the.

0 fitter-army desire-to look the switch in I c osedosition se thut the opereton will be w relieve -of the necessity of holding the switclflosed i The object of invention is to provide a. controlling mechanism including a switch whioktends atall timwto-move'intoopen en position, and means associated with the switchwperating member and arranged sothat it may be set' to eutomaticelly look" the switch in L closed" position on to permit the switch to move automatically" into its 45' open position. p p

A further and incidental ohj eeta-is'wo'prm vide' a switch mechanism aesoeiadzed' withl' the handle of an electric tool and heving a locking means which is especially adapted 00 for convenient opemtiom to release the switch instantly w en'occasion-r ires;

The 'ob yeets of the invention t s generally stated together with other and I email liu'yadvantages flI'G-fittflillfid? by the: 0011-- u ilfustrated' in the moom'panying oriable grinders, v.

drarwingss forming; part; hereof. l have: illustra'ted; blltTOllB. form ofimy inventiomiit being contemplated. that various changes may be made by thosei skilled: in the: artl withouti departingafrnm the spirit. and scope: of? the: inventionas expressed in! the" ape pendedi claims-: i p

'Figures l' ofithe drnwings is a sidesel'evm tionalz View of an electric: drill equipped: with a controlling." mechanism; constructed in 1 accordimce with my; inventiomn Ei'g. 21s afragmentary: underside view ofithe" con-r trolling mechanism as; applied. to the? side" of the drill: Fig: 3.is-1a frontrsideelevationali View oil the control devices Fig: 4 is an elevational :view: partly. im -section look; ing: into the interior ofrtheswitoh; casing:

I have selected? for purposes :ofillustrm-Q tionv a portable: electric drill? comprising at casing 7 enclosing an electric. motor 8: and: suitable operative connections. (not shown): the. motor and the drill chuck. 9;. 10 designates ai=handle\a/t' the upper: end of the casing, and 11' and 12 designate? side: handles extendin radially from a the" casing. 7 at diametrica y opposite! sides thereof; The handle 11 is suitably iastemddmaho'ssx or enlargement 13'; and the handle: 12: is": carried 1 by; wlrousing- '14 fDII' the switch? dese: ignated generallybythei minim-e145; (Fig. 4): Sai housinggi's-suitably securedto the side oithe casing 7 as hyimeans-of screws 16'. Electric current passesto" motor 8 through conductors 17, one of which passes intoand outwf the switch: housing =14! for connection with the switchierminals in: a weil knowmmmnerr The stvitch 15- hereinr showm comprises m plunger-'18 slidwble' in"a bracket l and con meted by means of a co'iIed' temiOn spring 2O with arpi-voted yoke 21 constituting-the movable switch conta'ctz A pair of station my contacts 22 (one only being herein shown) is mounted upon an insulated base? plate 23 and-connected with: binding post's 24towhich extend the conductors 17. A0 coiled compression spzing 25" normally h oldssthe plunger 18' in its =outermost: position in' tlr'e'bracket 19, andflimth'e reciproce tion-of the plunger the swingingcontnetfil 195 operates with a" sneppin f action into and out' of engagement witlr t "e'" stationary contests 22.

To; operate the plunger 18* to close the l switeh; a lever 261s at 27 iuth'e.

lower portion of the housing 14 near the forward edge thereof. This lever operates in a slot 28 formed in the lower side or edge wall of the housing, and the free end of the lever has a foot or bearing portion 329 which rests slidably upon a head 30 of insulating material carried by the free end of the plunger 18.

It will be seen that in order to maintain the circuit closed the operator, with the construction thus far described, must retain his hold upon the switch lever 28 which he can conveniently do because of the association of the switch with the handle 12. In Fig. 1 I have shown in broken lines the switch lever as applied to the handle 10. In either case, the lever is held in its closed or inward position by a linger or the thumb of the hand upon the handle, and it will be apparent that immediately upon the release of the lever the tool will. come to rest. lVith this arrangement the tool is capable of operation with maximum safety to the operator, his co-worl ers and to the tool itself. However, in order that the tool may be capable of operation so as to release both hands of the operator for other work and at the same time provide for the opening of the motor circuit with maximum ease and rapidity, I provide a locking means for the switch comprising a retaining or hook member 31 pivoted at 32 near the free end of the lever 26 and on an axis parallel with the pivot 27 for said lever. The pivot 32 may be mounted, in an enlargement or rib 33 upon the lower forward side of the housing, the rib being suitably cut away or notched at 3 t to receive the retainer member and permit of its swinging movements to be presently described.

The lower end of the member 31 has a portion 31 extending rearwardly substantially at right angles to the main portion of the member and adapted to engage with ashoulder 35 formed by the lower end of a plate 36 which is fast upon the free end of the switch lever 26. Since the latter is made preferably of aluminum, the plate 35 is formed separately and made of steel. or other suitable wear-resisting metal. A coiled expansion spring 37 is interposed between the retainer member 31 and the forward side wall of the switch housing so as to tend to force the hook 331 against the plate 36 on the lever 26, whereby when the latter is operated to close the switch, the hook will snap into engagement with the shoulder 35 to lock the switch lever and hence the switch in closed position. The spring 37 preferably encircles a pin 38 carried by the retainer member 31 and it enters a socket 39 in the forward side of the housing.

It will be observed that the retainer mem-.

ber 31 extends upwardly almost flush with the upper side of the housing and along the forward face thereof. The member is thus -in convenient position to be tripped by the hand of the operator on the handle 12, whereby to release the switch for movement into its open position. I have found in practice that the switch may be released much more rapidly than is possible with switches of the non-automatic type which require a distinct manual operation to open the circuit. Thus with the present construction a mere touch upon the free end of the retainer member is sutlicient to release the lever 26 for outward movement.

If now it is desired to render the retaining or locking means inoperative, this may be done by means of a small slide plate 40 mounted upon the underside of the rib 33. Said plate is secured upon the rib 33 by means of a screw ll, being slotted centrally thereof to receive the screw. At one side of the slot the plate is extended forwardly to form a finger 42 which is adapted to enter between the retainer member 31 and the adjacent wall of the housing, thus constituting an abutment for the upper portion of the retainer member to prevent it from swinging into engagement with the shoulder 35 under the action of the sprin 37. The plate has a central hump 40 whic is so positioned with respect to the screw 41 as yieldingly to resist sliding movement of the plate into either extreme position.

It will be seen that by the provision of the retaining means which I have provided, the tool is capable of operation with the controlling mechanism semi-automatic, to provide a. maximum safeguard against injury, or with the control mechanism automatically locked in position to maintain the circuit closed but permitting the instant release of the switch for movement into open position. Thus, in either event, the possible injury to the operator and to the tool is minimized.

From a manufacturing standpoint the re taining device can be applied to the control mechanism at a practically negligible cost and the construction is such that it will not wear out readily nor require frequent repair.

I wish especially to point out that the invention is not limited to the application of my improved retaining device to switches of the specific character herein illustrated and described, nor to switches located upon the side of the tool as in the present instance, for it is contemplated that it may be used wherever the switch is located whether it be upon the side of the tool, in the handle 10 or elsewhere.

I claim as my invention:

1. In an electric tool, the combination of a switch having a swinging contact, a reciprocable operating member having a resilient connection with said contact to swing it, a spring tending to resist the movement of said operating member to move said contact into closed position, an operating lever engaging said plunger to 0 rate it, and means or locking the lever an thereby the switch in closed position.

2. In an electric tool, the combination with a control mechanism comprising a switch having a swinging contact member, a plunger resilient] connected with said memer, a spring ten ing to resist movement of said plunger in one direction, an operating lever pivoted at one end and operatively associated at its other end with said plunger, and means associated with said lever adapted to engage therewith automatically whereby to lock said swinging contact member in closed or operative position.

3. In an electric tool, the combination with a control mechanism comprising a switch having a swinging contact member, a longer resiliently connected with said memr a spring tending to resist movement of said plunger in one direction, an operating lever pivoted at one end and operatively associated at its other end with said plunger, means associated with said lever adapted to engage therewith automatically whereby to lock said swinging contact member in closed or operative position, and means for holding said retaining member in inoperative position; 4. The combination in an electric control mechanism of an operating member, and a device for locking the operating member in a predetermined osition, spring means tending to move the device in one direction, and a slide plate movable into engagement with the lever to prevent movement of the lever by such spring means.

5. The combination in an electric control mechanism of an operating member, and a device for locking the operating member in a redetermined position, spring means tendmg to move said device in one direction, and a slide late movable into engagement withthe device to prevent movement thereof by such spring means, said slide plate having means for resiliently holding it in either operative or inoperative position.

In testimony whereof, I have hereunto affixed my signature.

JAMES J. GEBHARDT.

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