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Publication numberUS2519936 A
Publication typeGrant
Publication dateAug 22, 1950
Filing dateJun 20, 1946
Priority dateJun 20, 1946
Publication numberUS 2519936 A, US 2519936A, US-A-2519936, US2519936 A, US2519936A
InventorsKenneth J Sayre
Original AssigneeKenneth J Sayre
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Portable power tool
US 2519936 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

A118'. 22, 1950 K. J. SAYRE 2,519,936

PORTABLE POWER TooL Filed June 2o, 194e 2 sheets-sheet 1 Aug. 22, 1950 K. J. sAYRE PORTABLE POWER TOOL 2 Sheets-Sheet 2 Filed June 20, 1946 `Patented ug. 22, 1950 UITED STATES ,ATENT OFFICE 4 Claims.

This invention relates to portable power tools, and more particularly to la portable .tool in geombination with an internal combustion `engine adapted to `be .supported upon the back of the user. Preferably, the internal combustion en- 5 gine will be of the air-cooled, two-stroke cycle tion oi the invention is thereby intended :and that type, quite similar to the `small outboard marine various `changes and alterations are 4con-templated engines no'win comm-on use. such `as would ordinarily occur to .one skilled in It is a principal object .of the present invention the art to which the invention relates. to provide a portable tool .of the type described. Referring to Figures l and the present incomprising a supporting structure adapted to be vention comprises van internal combustion engine worn upon the back of the user, an internal comdesignated generally by the reference character bustion engine supported upon said structure, and lil connected by means of a next drive shaft a tool connected to said engine through a exible with a tool l l supported within a housing l2, drive shaft, the supporting structure comprising which housing is attached to .a rhandle lladapted an air intake passage Vthrough which cooling air `to be supported by the hands .of the user. The for the engine is drawn, thereby insulating the engine il? is supported on the back or the user back yof the user from the vheat of the engine. throng-h t e medium of a supporting structure A further object is the provision of a portable Vis. which may suitably secured upon back tool of the type described including a handle of the user by means of straps i5. The support.- structure for supporting the tool in use, said ing structure le is `Vmate hollow zcomprises handle structure including 'hand grips and engine the air intake passage for .the cooling air supply control means connected to the engine by lexible to theengine means such as Bowden wires 'or the like. The engi-ne -lil is preferably of the twofstroke A further object is the provision of a portable `cycle type and is quite similar to small outboard tool of the type described in which the flexible marine motors now in common use. Its Single drive shaft is connected `to the engine through cylinder it' is provided with cooling fins in .the an adjustable slip clutch, whereby damage to the usual manner, and the flywheel ll is vprovided tool and/or the engine is prevented in the case of with peripheral vanes l ii. A hollow structure lil the tool encountering an obstacle or being overconnects the llywheel ll with the space surrcundloaded, ing the upper portion of tho cylinder i6 and serves A further object is the provision of a portable as a passage for the cooling air which forced tool of the type described in which the direction downwardly by the varies A3 as the flywheel roof airow through the supporting structure may tates. be reversed, whereby the supporting structure Air iS Supplied t0 the VSIISS E3 'fhl'llgh the may be warmed with the heat of the engine dursupporting structure M which may be of alumiing cold weather. num or other light metal, or of other suitable Other and further Objects features and :admaterial. The SllllCllle Hl iS relatively Wide vantages will be apparent from the description and shallow, and is preferably shaped approxiwhich follows, read in connection with the acmately to the conformation of the back of a percompanying drawings in which son, so that it may be comfortably worn by the Figure l is an elevational view of a tool conuser of the tool. The engine lil is supported structed in accordance with the invention, with upon the structure le through the medium of a the power source attached to the back 'of the bracket or arm 2G which may be riveted or otheruser; wise secured to the structure le. En the illus- Figure 2 illustrates the 46001 0f Figure l in side trated embodiment, the rotation of the iiywheel elevation, With the COOlng air passages 0i the ll will cause cooling air to be drawn upwardly internal CQmbuStOIl engine Shown partly in verthrough the structure lll and forced downwardly CalSeCOn; past the cylinder I6, the passage of the cooling Figure 3 is a top plan View of the power Source 50 air through the structure lil serving to insulate illustrated in Figures l andZ; the back of the user from the heat generated by Figure 4 is a bottom plan View oi one type of the engine. In cold weather, a substitute fan tool adapted to be operated in Iaccordance with portion having reversely inclined vanes may be the invention, together with its housing; and applied to the ywheel I7, whereby heated air Figure 5 is a plan view of the cutting tool of will be forced downwardly through the structure Figure 4.

In order to facilitate ,en understanding of the invention, reference is made to the embodiments thereof shown in the accompanying drawing@ and .detailed descriptive language is employed. 1t will nevertheless be understood that ,no limita The engine is provided with a carburetor 2| including a fuel Valve operated through the medium of an arm 22 which is connected by means of a link 23 to a bell crank lever 24. The latter is disposed exteriorly of the clutch and governor housing 25 and is secured upon a shaft 26 which extends into the housing 25. A yball governor (not shown) of any suitable type is enclosed within the housing 25, and serves to control the fuel valve through the medium of the shaft 26, lever 24, link 23, and arm 22. The fuel valve may also be manually controlled through means to be described. The housing 25 also contains an adjustable spring pressed clutch (not shown) connecting the crankshaft of the engine With a heavy duty flexible shaft contained within the flexible housing 21. flexible drive shaft is secured to the cutting tool Il as seen in Figure 2.

The handle I3 upon which the tool housing I2 is supported is generally similar to a scythe handle and is provided with two spaced hand grips 29 and for manipulation of the tool. A fuel control lever 3| is associated with the hand grip 30 and is connected by means of a Bowden Wire 32 with the bell crank lever 2d, thus providing manual control means for the luel valve. A clutch control lever 33 is associated with' the hand grip29 and is connected by means of a Bowden wire 34 with a lever 35 secured upon a shaft 3G which extends into the housing 25 and operates the clutch.

The tool illustrated in the present embodiment comprises a serrated disc adapd for cutting weeds, and the housing or guard l2 is provided with V-shaped notches or serrations as seen in Figure 4, to admit the weed stems to contact with the teeth of the cutter. Obviously, other tools may be substituted for the cutter Il, as for example a saw blade, a wire brush, or the like, in which case modlication of the housing I2 would be required, depending upon the type of work to be performed. Modification of the shape of the handle I3 would also depend upon the type of tool to be driven and the nature of the work to be performed.

Having thus described the invention, what is The lower end 28 of the claimed as new and desired to be secured by Letters Patent is:

1. In a portable tool including an internal combustion engine, a supporting structure comprising a hollow member open at two points one of which is adjacent the combustion area of said engine and the other of which is removed therefrom, means supporting said engine on said structure, and means for passing air through said structure.

2. In a portable tool including an internal combustion engine, a supporting structure comprising a hollow member open at two points one of which is adjacent the combustion area of said engine and the other of which is removed therefrom, means supporting said engine on said structure, and means operated by said engine for passing air through said structure.

3. A device according to claim 1, said supporting structure consisting in a relatively wide and shallow conduit shaped approximately to t the back of a person.

4. For an air-cooled internal combustion engine, a supporting structure comprising a relatively Wide and shallow conduit, said conduit being curved approximately to fit the back of a vperson and having an orifice adjacent the combustion area of said engine, and means for supporting said engine on said structure.


REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,370,768 Sperling Mar. 8, 1921 1,981,076 Sells Nov. 20, 1934 2,119,962 Raleigh June 7, 1938 2,326,335 Dehn Aug. 10, 1943 2,434,089 Allen Jan. 6, 1948 FOREIGN PATENTS Number Country Date 138,928 Austria Oct. 10, 1934

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1370768 *Jun 27, 1917Mar 8, 1921Rotary Scraper Company IncPortable tool-working device
US1981076 *Jun 1, 1931Nov 20, 1934Stanley N SellsPortable motor
US2119962 *Mar 2, 1936Jun 7, 1938John RaleighApparatus for extinguishing forest fires
US2326335 *Jul 26, 1940Aug 10, 1943Fairbanks Morse & CoAir cooling of engines
US2434089 *Jul 14, 1944Jan 6, 1948Allen Herbert EPortable drill tree tapping machine
AT138928B * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2699636 *Nov 2, 1953Jan 18, 1955Briggs & Stratton CorpRotary lawn mower
US2722955 *Jun 3, 1953Nov 8, 1955Roy Earl EElectric powered saw for cutting brush
US2725753 *Jul 18, 1951Dec 6, 1955Haug Richard JPortable power operated tool
US2737774 *Feb 24, 1953Mar 13, 1956Sidney S StiersShield for engine mufflers associated with sawing machines
US2790292 *Feb 16, 1954Apr 30, 1957Francis J TreckerPower transmitting, towing, and cutting attachment for power mowers
US2792670 *Dec 18, 1953May 21, 1957Haynes Lester NTree girdler
US2815050 *Aug 22, 1956Dec 3, 1957Haug Richard JAngular power transmission tube
US3212246 *Apr 1, 1964Oct 19, 1965Howard K DukeRotary mower attachment
US3219129 *Mar 15, 1963Nov 23, 1965Sakuji YamadaWorking device portable on the operator's back
US3221481 *Aug 19, 1963Dec 7, 1965Sunbeam CorpCombination lawn edger and trimmer
US3283986 *Jun 25, 1964Nov 8, 1966Powers Wire Products Company ITie-wire installation apparatus
US3346955 *Jul 15, 1965Oct 17, 1967Beneke Howard ETree and hedge trimmer
US4006528 *Nov 5, 1975Feb 8, 1977Kaaz Machinery Co. Ltd.Portable grass and brush cutter with brake and clutch
US5011058 *Jan 30, 1990Apr 30, 1991Textron Inc.Leaf blower back pack frame
US5176303 *Apr 29, 1991Jan 5, 1993Textron Inc.Back pack with fuel tank
US5716131 *Jun 28, 1996Feb 10, 1998Breeding; Kenny D.Portable four cycle backpack pendulous vibrator
US6065859 *Nov 2, 1998May 23, 2000Iskoo LtdPortable pendulous concrete vibrator
US6745475 *Nov 22, 2000Jun 8, 2004Andreas Stihl Ag & Co.Brushcutter
US20080189958 *Apr 11, 2008Aug 14, 2008Hurley Edward PShield for a string trimmer
USRE37081May 27, 1994Mar 6, 2001Steen M. EriksenBackpack vacuum cleaner
DE904122C *Jan 1, 1952Feb 15, 1954Karl JacobTragbare Erntemaschine
DE912031C *Nov 24, 1951May 24, 1954Ernst WielandMotorisierter Maeher
EP2587013A1 *Oct 23, 2012May 1, 2013Yamabiko CorporationBackpack work machine
EP2995186A1 *Aug 26, 2015Mar 16, 2016Yamabiko CorporationBackpack type working machine
U.S. Classification224/261, 172/41, 123/41.65, 123/41.31, 56/10.4, 56/12.8, 30/276
International ClassificationA01D34/90
Cooperative ClassificationA01D34/902
European ClassificationA01D34/90A