US1307968A - harrah - Google Patents

Description

' P. J. HARRAH.

LIFTING JACK.

APPLICATION lFILED MAY 6.

Patented June 24, 1919.

1 .Ilm

Mii livr ToaZZ whom/t may concern". y i i Be it linoivn `that l, Pi-IiLiiljJ.WHARRAH; of Bloomfield,` in the county of Greeneand St a te ef `indiana,` have invented i certain new and usefull Improvements in Lifting-Jacks.; andl do hereby declare the following tefbe afull, clear,\ and" exact description of the invention, such as Will enable others skilled in the art to which it appertains` to unake anduse thesaine. "1^ 15 ln this invention inyiobjectis to imprevel` that class of devices in which the`.loiveringA action as i ivell as thefllifting movement effected step by step.` Broadl-y` statedl leinploy a standardhaving` a pluralityofper-l forations and apair ofurunners movable on-y the standard. Each of theirunnersvisupro-l vided with a springactuated pinfadapted ners in the oppositiedirection.

ln the accompanying` drawings. Figurewlr` is a sideelevatiovn, Fig; `29a@vertical see-' lion and Fig. 13 a detail of the reversing plate. Fig. lis a fragmentary view in side elevation oppositeto Fig.i1.`i

l have shoivn an upright standardl `1Y mounted upon i a! g suitable l pedestal 2 and f formed with a 1 vertical series `of perforations These extend entirely through the stand-` ard so that it may be reversed when fthe surfaces surrounding the perforations i become Worn. 3 and L shoiv the runners coinprising sleeves preferably rectangular in cross section to correspond to the formation of the standard; The operating lever 5 isi of bell-crank formation at its inner endafsat"` 5 Where it is shown fulcruined to the upper runner 4 as at 6. The runners are connected by a vertically disposed pitniaii 7 fulcrumed to the lower runner 3 as at 8 and tothe bellcrank portion of the lever 5 as at 9. Thus the pitinan operates as a movable fulcrum in the lifting' action and it and the lever constitute a toggle link mechanism. When the runner 3 is fixed, the fulcrum of thelever action is at 9 and when the ruimer 4 is fixed the fulcrum is at 6. The ruimere is shown provided with the usual foot or step 10.

l have shown the lower runner 3 apertured to receive a pin 12 having a cross arm 13 and liavinpgits outer extren'iity movable in a bearing formed by a bracket 14 which y tf-Therperforations inthe standard areso ATENT OFFICE nLfooii/iiiiinn. iivinraiva.

sriaiirefzeaeig u e castlintegrallyWith the runner. `A` spring 15 is shown coiled `uponthe-pin and bea-rs at one end against the cross` arm and at the other endagainst the bracket."` The tendency ofthe spring is to project the pin inward `and into one of tlieperforations 2 ofthe staiidard ivhen the pin and a perforation are `in alineinent. At its" outer eX- ti'eniity the pin is beveled at its upper side asf-w16."` By upper side I have reference toi the side facing the top of the standard Wheirthe device is used in an upright position` The purpose ofthe bevel is that `When anliftingforce `is `exerted upon the runner to drawititoivard thetop of the standard the beveledisurface 16 `will alloivthe pin to `slide overl the Wall of the perforation in `which ithas been seated The straight or uninterruptedformation at the opposite side of the pinyasiat 17. preventsthe pin withdrawing when the Weight is bearing upon the runner.` VVheir the ruimer is tojibe positive Withdrawalofthe pin.

iThe runner f-l is equipped Witha pin 1S, crosswarin "19, bracket 20,1 spring 21 and beveled extremity 232i similar to the parts above described with relation to runner 3.

moveddownwardit is necessary to effect `the disposed that in `the movement ofthe runne'rswthe pins l2 and 181 Will not both be projected into the perforations at the same f time. lhen one pin is projectedthe other pinuis resting' or inovingon the surface be-` tween ltivo of the perforationsm From what `has thus ifarbeen" said it will beunderstood that with the pin 12` of runner 3 seated in a perforation as in Fig. 2. the ldyvnward ii'ioveinent ofthe lever 5` Will lift t ie"1 and the fulcruin of the toggle link mechaiiisin at 9. Runner L1 is elevated until its pin 18 snapsinto a perforation.` Raising the `lever 5 shifts the fulcrum to the point (3 and the pitman 7 elevates the runner 3 until its pin 12 snaps into a higher perforation.

This action is continued during theelevation of the ack.

The reversing mechanism is shown consisting of a plate 23 bridging' the space betvveen the tWo runners and having appropriate bearing spaces provided by the brackets 14. and 20. This plate `is adapted to be longitudinally movable and is under the tension of a spring1 24 shown seated in a housingr@` 25 formed in the upper runner 4 and '95 ruimer 4, the Weight being at point 6y bearing against a lug 26 formedv on they plate. f The plate is shown formed with upper andlower cam surfaces 27-28 so disposed as to be in operative relationship to the cross arms 19 and 13. The reversing platev is shown formed with a curved upper p' extremity 29. A cam switch 3() is pivoted on the face of the runner 4 lwithin a-slotted depending portion 31 of the reversing plate.

` In the lifting action the reversing plate is in the position shown, that is, elevated against the tension of its spring.

1When the switch 30 is turned downward so that its cam surface permits the plate 23 to dropunder the tension of spring 24, the vcams 27, 28 will be brought close to their respective cross arms 19 and`13.

The subsequent operationof the lever 5 will cause the cross arms to ride up on the cam surfaces and effect the positive withdrawal ofthe pins so as to permit the downward travelof the runners in step by step action. In this mannerthe toggle link mechanism whichpreviously only permitted of va raising action now 'allows of a lowering of the parts. By forming the standard with perforations extending entirely through its thickness it may be reversed so that the pins of the runners will operate on one or the othervof its sides. After some use on one side, the 'left as in Fig. 2, for instance, the walls around the perforations may become worn by the action of the pins. The standard may then he turned so that its right side will receive the pins. This prolongs the termv of usefulness of the standard in `addition to insuring ample bearing surfaces in which-the pins-.are supported when seated.

The essential elements of my invention. are adapted as. well for wire stretching as for wagon jacks.

I elaimas my invention:

1. A lifting jack comprising a standard having a plurality of -perforations extending entirely therethrough, a pair of runners movable on said standard, a spring actuated pin carried by each of said runners for alternately entering said perforations to constitute a vfixed stop while the other runner is advancing, a lever fulcrumed to one of said runners, and a pitman connecting said lever with the other runner.

2. In a lifting jack, a standard having per forations, a pairv of runners having pins adapted to engage said perforations, means for projecting and withdrawing the pins, meansfor alternately advancing one of said runners while the pin of the other runner is projected i-nto one of said perforations, and a reversing element having means for controlling'the projection and withdrawal of said pins .to reverse the direction of travel of said runners.

3. In a lifting jack, a standard having perforations, a palr of runners, a spring actuated .pin having a cross arm and carried by each lof said runners adapted to be projected into said perforations, means for alternately advancing one of said runners while the pin of the other runner is projeoted into one of said perforations, and a reversing plate having cam surfaces adapted to engage said cross arms to alternately withdraw Said pins and reverse the direction ofk movement of the runners.

4. In a lifting ]ack, a. standard having perforations, .a pair of runners, spring actu-y ated pins on said runners having cross arms and beveled at one side of their extermities. means for alternately advancing one of said runnerswhile lthe pin of the other runner is projected into one of said perforations, a reversing plate having cam surfaces adapted to engage the cross arms `to alternately withdraw said pins and reverse the direction of movement of the runners, and means for maintaining said reversing plate ineffective during the action of raising said runners.

In testimony whereof I have signed this specification.

PHILIP J. HARRAH.

Copiesof this patent'may be vobtaimad for five .cents each,.by addressing the Commissioner of Patents,

' Washington, D. C.

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