US961106A - Screw-jack. - Google Patents

Description

M. G. G/UMMING.

SCREW JACK.

APPLICATION FILED AUG.16, 1909.

Patented June 14,1910.

'prtof the s UNITED sTATEs PATENT OFFICE.

MILLARD C. CUMMING, 0F TIGEBBAY, FLORIDA', ASSIGNOR 0F ONE-HALF T0 L. W.`

COTTMAN, 6F TIGERBAY, FLORIDA. l

SCREW-J ACK.

To all whom itmay concern:

Be it known that I, MILLARD C. GUMMING, a citizen of the United States, residing Tigerbay, inthe county of Polk, State of Florida, have invented certain new and useful Improvements in Screw-Jacks; and I do hereby declare the following to be a full, clear, 'and exact descriptionl of the invention, such as will enable'others. skilled in the artito which it appertains to'make and use the same. V

. This invention relates to im rovements in liftingjacks and has forits o ject the provision of a device of that kind which may be extended to a len th substantially equal to twice the length o its supporting standard or base.

Another object is the provision of a stop serving to prevent the threads on the liftin sections from binding during the outwar or lifting movement of one of the lifting sections.

With these and other objects in view as will more fully hereinafter appear, the resent invention'consists in certain nove details of construction and arran ement of parts, hereinafter fully described, lllustrated 1n the accompanying drawin and more particularly pointed out in t 'ef-appended claims; it being understood 'that various cha in the form, roportion, size and minor details of the evice may be made without departing from the spiritor sacricing any ofthe advantages of the invention.

In the accompanying drawings forming ification: Figure 1 isa side elevation of t e device. Fig. 2 is a sectional view thereof. Fig. 3 is a bottom plan view taken on the line 33 of Fig. 1 and showing one portion ofythe toothed clutch.

ASimilar numerals of reference are employed to designate corresponding parts throughout.

The u right or base is designated in eny.eral by t e numeral 5 and is shown to. e a

'tubular structure interiorly screw threaded as shown atv 6. The outer surface of this upright or base is flared from its upper end and is providedf with the usual handle 7. The threads 6 extend for the entire length i of the base 5 and engage with the exterlor threads of an inner section 8. TheY inner 4section 8 is screw threaded throughout its length corresponds in length to the Specication of Lettersilatent. I

Application led August i6, 1909. Serial No. 513,199.

aty

imparted Patentedrime 14, 1910.

thickened head 9. The thickness of the head 9 corresponds approximately to one eighth the length of the inner section 8, and formed centrally of the head 9 is a threaded opening 10. The ,pitch of the threads in the opening 10 is the same as thepitch of the threads on the outer surface of the inner section 8 and inner surface of thesection 5, for a purpose to be presently described. The upper face of the head 9 1s flush with the upper end of the section 8` and formed in the upper face are a pair of diametrically oppslte clutch teeth 11, which are adapted to engage with a similar clutched surface to transmit movement to the section 8 in one direction only.

A second lifting section is designatedl in the length of thesection 8 and its lower or inner end is provided with a head 15, the upper surfaceV of which is provided with a "'palr of diametrically opposite clutch teeth .17. Formed on the lower face of the head 9 are a pair-of clutch teeth`18 similar to the clutch teeth 17 and which are adapted to engage with the latter when the head 15 is brought into engagement with the head 9. The clutch teeth 17 and 18 are so formed that they will impart movement to the section 8 in one direction only. The upper or opposite end of the shank 13 terminates in a lifting head 19, the up er surface of which is fiat and the lower sur ace of which is provided with a pair of diametrically opposed Yclutch teeth 20, which are adapted Lto 'engage with the clutch teeth 11 and imparta turning movement to the section 8 inone direction only and opposite to the'mov'ement b the clutch teeth 17. Thehead 19 1s providled with a transverse opening 21, which is adapted to receive a suitable tool, by means of which the head may be turned.

Having now described the structure of the .device its operation will be given. The jack is laced in the Ordinar manner under the ob]ect to be lii ed an la suitable bar or other tool is insel `ed through the openingrQl '.in the lifting head 19. By turning the lat,-

ter in `one direction so that the bearing sur'- faces of the clutch teeth 20.011 the lower face of the head and the clutch teeth 11 on the upper face of the head 9 are moved into en-y gagement with each other the section 12 will ascend-on the threads of the opening 1Q in.

'the head After the section 12has asment ofthe section 8' on the threads'6 that' thethreads 14 willbe prevented from bindcended t0 its full extent the clutch teeth 17 on the head 15 at the lower end of the shank will engage with the clutch teeth 18 on the lower face o fE the head 8 whereby a 'rotary movement will beiimparted to the section' 8, which will cau'sethe latter to ascend on the thread 6 o-f the base 5. It will be observed that duringthe upward or outward moveingv "onfthe threads of the opening 10by virtue of the clutch teeth 17 and 18, since the bearing surfaces of these teeth will be in engagem ent` and will thereby prevent upward onpasending movement ofthe shank 13 on the threads, ofthe opening 10 beyond a certain -point, so that when it is desired to dis-' engage the jack from the object lifted the turning movement of the head 19 in a direction to cause the section 12 to descend will not be prevented by the'threads binding.

It will be observed 'thatfthe device is exceedingly simple in Astructure and comparap tively inexpensiveto manufacture, and its utility will be greatly appreciated since with its use the employment of blocks, which are. usually interposed between the lifting head and object to be lifted when 'devices of this kind having but one telescoping 'section are used, will not be necessary; for it is evident that after one section has been extended to lits full extent and it is required to raise the tubular basesection, a plurality of screw threaded telescoping sections threaded intol said base, one ofl said sections being provided with oppositely disposed clutch surfaces 'and another of said sections lhaving similarly formed clutch surfaces to engage with the clutch surfaces of the first-named lsection so as to cause the latter to ascend and descend on the threads of the base section.

3'. In .a lifting jack, an interiorly threaded tubular` base section, a lifting section threaded into said base and provided at its upper end with a head having onits oppo-l site faces a plurality of clutch teeth, a third section threaded/'into the second section having heads at its opposite ends the inner` faces ofwhich are provided with clutch teeth to engage with the teeth on the said second section so as to cause the latter to ascend anddescend on-the threads of the base'section.

In testimony whereof, I alix my signature, in presence of two witnesses.

MILLARD C. CUMMING. Witnesses:

FRANK W. ZANDER,

W. ZANDER.'

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