US455993A - Lifting-jack - Google Patents

Description

(No Model.) 3 Sheets-Sheet 2 J. BARRETT.

LIPTING JACK.

Patented July 14, 1891.

we Noms paens co., puuwurnn., msnmmon, u. c.

(No Model.) l 3 sheets-sheet J. BARRETT.

LIPTING JACK. y

Patented July 14, 1891.

A. muvo-uma.. wlsmnarnn u c UNITED STATES PATENT OFFICE.

JOSIH BARRETT, OF ALLEGHENY, lASSIGNOR TO-VTHE DUFF MANUFAO- i TURING COMPANY, OF PIT'ISBURG, PENNSYLVANIA.

SPECIFICATION forming part of Letters Patent No. 455,993, dated July 14, 1891.

Application filed February 13, 1891. Serial No. 381,275. (No model.)

T0 @ZZ whom it may concern:

Be it known that I, JosIAH BARRETT, a resident of Allegheny, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Lifting-Jacks; and I do hereby declare the following to be a full, clear, and exact description thereof.

My invention relates to what might generally be termed lifting-jaeks-that is, to

power mechanism in which a step-by-step movement back and forth is obtained, said mechanism being actively operated in one direction to move or raise a load and passively operative in the other direction to control the movements of a load, such as in lowering a load lifted by the jack. By such terms it is of course to be understood that the invention includes any device embodying` :its principle,

whether the power is exerted ina vertical,

horizontal, or other line.

My invention relates to the same general class of jacks as set forth in Let-ters Patent No. 312,316, granted to me February 17,1885, and has practically the same objects in view.

It consists, generally stated, in a jack having a barv provided with teeth on one side thereof and hand or operating lever pivoted therein, two pawls pivoted to the lever and engaging with the .toothed bar, fingers rigid with said pawls, and a yielding tripping-plate having lugs thereon adapted to engage with the fingers of the pawls and by the pressure thereof to withdraw the pawls from engagement with the toothed bar, so that while the jack can operate in substantially the same way as described in said Patent No. 312,316 in raising the load, where it is desired to lower the load the tripping-plate is brought into` position for engagement with the lingers of the pawls and as one or the other pawl is drawn downwardly its finger will press against Athe tripping-plate, which plate will then yield until that pawl is relieved of the weight of the load by the other pawl, when the pressure exerted by the tripping-plate through said finger will draw the pawl away from this toothed bar and hold it from the same until it is raised into position to again engage there- 5o with. The particular points of the invention illustrating the jack and showing the position of the parts when the jack is arranged for raising a load,-showing a weighted lever operating the yielding tripping-plate. Fig.

2 is a like View showing the position of the parts when arranged for lowering the load, showing the upper or outer pawl withdrawn, and also showing the power applied to the tripping-plateby a spring. Fig. 3 is a like V1ew showing the inner or lower pawl withdrawn, and showing the power applied to thc tripping-plate by the weighted lever. Fig. 4 is a detail view showing the position of the parts of Fig. 2, and Fig. 5 is a back view of the tripping-plate.

Like letters indicate like parts.

The general body of the jack and toothed bar in the preferred form thereof correspond to those shown in said Patent No. 312,316, and need not be particularly7 described herein, the frame or stand A being generally rectangular in cross-section and having a like passage or guideway therein for the lifting-bar B, and.

said toothed or lifting bar having the foot ZJ, which fits within 4the ordinary slot formed in the forward face of the jack. The bar B has the teeth formed only on one side thereof, so that the two pawls will engage with this one ratchet or toothed face.

The frame or standA ot thejack has formed therein the socket or bearing a forthe reception of the inner end of the operating or hand lever O, and pivoted to this hand-lever are the pawls (l c, these pawls being preferably arranged as described in said patent-thatis, being pivoted oneaeh side of the fulcrum-pin c of the hand-lever. The inner pawl c is pivoted forward of the fulcrum-pin, and hence is adapted to engage with and raise the toothed bar when the hand-lever O is lowered, and the outer pawl d is pivoted back of the fulcrum-pin c and is of greater length than the pawl e, so that it engages with the toothed bar reo above the same and is adapted to engage with andraise said toothedbar when the hand-lever C is raised. Tlie pawl e has rigidly secured thereto the finger e, which preferably eX- tends downwardly therefrom, and the pawl d has a like finger drigidly. secured thereto and preferably extending downwardly therefrom, these two fingers being adapted to engage with the tripping-plate F. The exact shape of the fingers is not particular. The tripping-plate is mounted in any suitable way upon the jack-frame A, being shown in the drawings as pivoted to the same at f, though it is evident that it may be mounted to slide therein, as shown in said Patent No. 312,316. Said tripping-plate has the two lugs g h, which are formed on the inner side thereof, and are shown in dotted lines in the figures of the drawings, and are in such position that when it is desired to lower the toothed bar and the tripping-plate is brought into its operative position thelugs of the plate will be adapted to engage with the rigid fingers of the pawls when said pawls respectively are lowered.

The tripping-plate can be operated by any suitable power, either by a spring, as shown at k, Figs. 2 and Ll, or by a weight, as shown in Figs. 1 and 3. In either case the trippingplate is yielding, so that when one of the finf gers on the' pawls engages therewith, as the pawl 1s in engagement with the toothed bar and the finger is rigid therewith, the trippingplate will itself yield until the other pawl takes the load and frees that pawl, when the pressure applied to the tripping-plate through the spring or weight will be transmitted through the finger to the pawl and draw it away from engagement with the toothed bar.

Where a spring is used, as shown in Figs. 2 and 4, it is necessary to employ some suitable mechanism for holding the tripping-plate F out of engagement with the fingers of the pawls when the jack is raising the load; and for this purpose I have illustrated an eccentric Z, adapted to engage with an arm f on the tripping-plate, and when turned tohold lthe tripping-plate back from engagement with said fingers d e', but when turned in the opposite direction leaving said tripping-plate free to contact with and yield to the pressure of said fingers, as above described. This same eccentric may be employed when a weight is used to apply the pressure to the trippingplate; an`d the construction of the jack when so arranged will be easily understood. This spring-operated yielding tripping-plate forms the subject-matter of application for patent filed by me April 30, 1890, No. 391,066, which is in part a division of this application. When, however, a weight is employedV to apply the pressure to the tripping-plate, I prefer to arrange it as shown in Figs. 1 and 3, the weight fmJ being pivoted at the upper end of the tripping-plate, as at n, and said pivoted weight having one lug p adapted to press against the bearing a of the hand-lever C, so that when the weight is brought into the position shown in full lines in Fig. 3, as the lug p bears against the bearing a, the pressure of the weight will be exerted to draw the trippingplate F backward and bring its lugs g and It l into contact with-the fingers d e. When, however, it is desired to raise the toothed bar,

the weighted lever m can be swung on its pivot n until the lug or finger' r of the lever bears against a pin s on the tripping-plate, and by such movement the lever is thrown past a perpendicular, as shown in Fig. 1, and will then act by its pressure Von the pin s to hold the tripping-plate out of con-tact with the fingers CZ e.

It is evident that, if desired, I may employ the weight m, mounted in substantially the Way above described, together vwith a tripping-plate having the finger f', and an eccentric Z, and by said'finger andeccentric may draw back the lifting-plate in the same manner as described in connection lwith the spring 7s, (shown in Fig. 2,) and so overcoming the necessity of mounting the weight, so that it can be swung pasta perpendicular, as above described.

The operation of the jack is substantially the same whether the weight shown in Figs. 1 and 3 or the spring shown in Figs. 2 and 4 is employed. When it is desired to lift the load, I either throw over the weight m, so that it bears against the pin s, as shown lin Fig. 1, or I turn the eccentric so'thatit enga-ges with the finger f ofthe tripping-plate and compresses the spring and draws the lugs of the tripping-plate away from the fingers of the pawls. In either case the pawls will by their own weight rest in contact with vthe notched face of the lifting-bar, and as the hand-lever C is raised it will, through the pawl d, raise the lifting-bar, the pawl e then descending and slipping over the notched face of the bar, and when the hand-lever is lowered the pawl e will engage with the bar and raise the same, while the pawl d descends, slipping over the notched face of the bar. This is continued, the one or the other pawl engaging with and lifting the bar B until the load is raised to the desired height.

. l/Vhen it is desired to reverse the motion of the bar B, either to lower the load or, where the jack is worked horizontally, to permit the lifting-bar to be gradually pressed back while its motion is controlled, I either draw back the weight m into the position shown in Fig. 3 or turn the eccentricl so as to leave the same free to be carried into position to engage with the fingers d e of the pawls d e. When in such position, as the hand-lever C is lowered the lifting-bar will be sustained by` the pawl d until the finger d comes against the shoulder g of the tripping -plate F, in which case the tripping-plate will yield untill the pawl e engages with the lifting-bar and acts to sustain the weight, when, as soon as the pawl d is free, the pressure upon the tripping-plate will, through the finger d', force the pawl cl outwardly, so drawing it away ffrolnlthe Shoulder g of the tripping-plate,

leaving the pawl d free to fall into contact with the lifting-bar, and as the operator con- 4.; tinues to raise the lever c the linger e of the "pawl e will come in contact with the shoulder .-"t of the tripping-plate, causing said plate to yield until the pawl d has taken the weight of thelifting-bar, when, as soon as the pawl e is freed from saidbar, the ltripping-plate will, by its pressure on the nger e', draw away the pawl e of thelifting-bar,holdingit away from thesame until upon the loweringof thehand-lever'the finger e is raised clear of the shoulderd, when the pawl e will fall against the liftingbar in position to engage therewith and receive the load from the pawl d; and the iin-l ger CZ of that pawl will again come in contactvwith the shoulder d, and, as soon as that pawl is free, lift it away from the lifting-bar, as above described, this being continued until the load is lowered as far as desired.

It will thus be seen that by the employment of a yielding tripping-plate and rigid fingers on the lifting-pawls a very simple form of vjack is obtained, and one which is not liable to get o ut of order, and it contains but few parts.

As above referred to, inthe term liftingjack I include any mechanism in which one main part or element thereof has a step-bystep movement which is actively operative in one direction to move or raise a load and passively operative in the opposite direction either to lower the load. or to control its movement, whether the same acts vertically, horizontally, or in any other direction.

What I claim as my invention, and desire to secure by Letters Patent, is-

l. In a jack, the combination of a bar having teeth on one side thereof, a pivotal lever, two pawls pivoted to said lever and having fingers rigid therewith, and a Vyielding trip- A ping-plate having lugs thereon adapted to engage with saidiingers and through the same draw the pawls from engagement with the toothed bar, substantially as and for the purposes set forth.

ing tripping-plate having lugs thereon adapted to engage with said fingers, and a pivoted weight engaging with said trippingplate, substantially as and for the purposes set forth. n

4. In a jack, the combination of a bar having teeth on one side thereof, a-pivotal lever, pawls pivoted to said lever and having iingers rigid therewith, a yielding tripping-plate having lugs thereon adapted to engage with said fingers, and the weight m, pivoted to said tripping-plate and haviug'the lug p engaging with the stationary frame, substantially as and for the purposes set forth.

5; In a jack, the combination of a bar having teeth on one side thereof, a pivotal level', two pawls pivoted to said lever and having fingers rigid therewith, the tripping-plate F, and the weight m, pivoted to said plate and having the lug r, adapted to press upon the.

.tripping-plate, substantially as and for the purposes set forth. Y

6. In a jack, the combination of a bar having teeth on one side thereof, a pivotal lever, a pawl pivoted to said lever and having a iinger rigid therewith, and a yielding tripping-plate mounted on the frame and having a lug adapted to'contact with said iing'er and through the same draw the pawl from engagement with the 'toothed bar, substantially as and for the purposes set forth.v

In testimony whereofl I, the said JOSIAH BARRETT, have hereunto set my hand.

.IOSIAI-I BARRETT.

l/Vitn esses:

J. N. COOKE,- RoBT. D. ToTrnN.

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