Improvements in Lifting Jacks.
Year: 1890

page_text: Date of Application, 23rd Jan., 1890-Accepted, 29th Mar., 1890
COMPLETE SPECIFICATION.
Improvements in Lifting Jacks.
I, MELCHOIR CHUMARD of Brooklyn in the County of Susquehanna, and State of
Pennsylvania, United States of America, Merchant, do hereby declare the nature of
this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
This invention relates to the class of simple lever-jacks, and the object of the
invention is mainly to simplify the construction and to effect an economy therein
without sacrificing important advantages, and to produce a jack which will enable the
weight to be both lifted and lowered gradually and carefully.
The invention will be hereinafter fully described and its novel features carefully
defined in the claims.
In the accompanying drawings which serve to illustrate the invention :-
Figure 1 is a perspective view of a jack embodying the improvements.
Figure 2 is a vertical, longitudinal section of the same taken in the plane of the
axis of the jack, and
Figure 3 is a plan of the jack.
Figures 4 and 5 are fragmentary detail views that will be hereinafter described.
The standard of the jack is preferably formed of a base-piece a and two uprights a¹
and a provided with grooves b in their inner faces, in which plays an extension
slide c.
The uprights a a² are tied together by a stout bar d at their upper ends.
This bar serves to strengthen the standard, and also to provide a handle to be grasped
by the operator whereby he is enabled to steady the jack when in use.
e is the operating or lifting lever of the jack, which lever is mounted on the slide c.
This lever is pivoted on a rod or pin fin a yielding or spring-like yoke g, secured at a
to the face of the slide c. The pivot-pin extends back through an aperture h
(Fig. 2) in the slide, and has a disc or plate fx on its rear end, between which and
the back of the slide c is arranged a coil spring i, which embraces the rearwardly-
extending end of the pin f. This spring i keeps the lever e drawn up elastically to
and against the faces of the uprights a', a³, on the standard.
In the upright a¹ are fixed fulcrum studs or projections 1, 2, 3, etc., in a row as
seen in Fig. I; and in the other upright a² are fixed similar fulcrum studs, k³,
k, k³, etc., in a row. Preferably, the studs of one row stand opposite the middle of
the spaces between the pins of the other row, as clearly represented in the drawings.
These studs or projecting parts form the fulcrums for the operating lever e, in lifting
the load. In Fig. 1, the extension slide c, is represented as supporting a load that has
been lifted by the jack.
Normally, the slide c of the jack will rest at its lower end on the base-piece a, of
the standard, and the free end of the lever e will, or may, under these conditions,
rest on the lower stud j¹ in the upright a'.
To operate the jack, the operator places it under the load to be lifted, in the usual
way, steadying it with the left hand by grasping the projecting end of bar d, and
grasps with his right hand the handle of fever e. He lifts lever e with the stud j' as
a fulcrum, until the end z' of the lever rises above the lowermost stud k' in the
upright a², and rests thereon. In order to make the lever pass the stud, he presses or
draws the lever outward a little, the yoke g and spring yielding enough to permit
this. Now, with the stud k¹ as a fulcrum, the operator depresses the handle of the
lever e and raises the end z thereof above the stud in upright a', and permits it to
rest thereon. He makes the lever pass the stud in the same manner as before
described with reference to stud k¹. Then with stud as a fulcrum, he lifts the
end of the lever up to stud k². Thus, step by step, and using the studs of the
respective rows alternately as fulcrums, the operator raises the load. The lever is one
Price 6d1

page_text: of the first class when a stud in upright a² is used as a fulcrum, and one of the second
class when a stud in upright a' becomes the fulcrum.
To let the load or weight down, step by step, the operator merely reverses the
operation above described.
To prevent the lever e from slipping on the fulcrum studs, it is preferably provided
with slight notches in its lower edge where it bears on the said studs; and in order
to enable said lever to "wipe" over the studs in rising, it is, by preference, slightly
bevelled or flared outward at its top or upper edge at the points where it passes the
studs. This flare is seen in Fig. 3, but more clearly in the fragmentary view Fig. 4.
In this view, the studs are also represented as having heads. If the lever e were
made of a flat bar of iron, as represented in the drawings, it might be swaged at
the points where it engages the fulcrum pins, until the inner face of the lever at
these points has the flare or bevel represented in Fig. 4. When these bevels are
provided, the lever will wipe over the studs in raising the load, without any special
attention on the part of the operator.
As seen in Fig. 4, the fulcrum studs may have heads, and these will serve as
guards to prevent the operating lever from slipping off from them. Or, in lieu of
studs driven separately into the upright or standard, a ratchet-strip or rack, j, as seen
in Fig. 5, may be employed. Indeed, the fulcrum projections may be formed in any
convenient manner.
One important advantage of the jack is the perfect control in raising and lowering
the load, the operating lever resting directly on the fulcrum, and no intermediate
pawl or dog being employed. This simplifies the construction, and enables the
operator to control the lowering of the load perfectly.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :-
1. A lifting jack, comprising as its essential features a standard, provided with a
keeper or guide-way for the extension slide, the said slide, mounted in said standard,
an operating-lever pivotally mounted on said slide and held up to the face of the
standard by a spring, the said spring, and fulcrum studs or projections on said
standard upon which the operating-lever bears in raising and supporting the load.
2. In a lifting jack, the combination with the standard and the extension slide
mounted therein, of the yoke g, mounted on said slide, the operating lever pivotally
mounted in said yoke, the spring which holds the operating lever elastically up to the
face of the standard, and the two rows of studs on the standard forming fulcrums for
said lever, as set forth.
3. In a lifting jack, the combination with the standard, the extension slide therein
and the fulcrum projections on said standard, of the yoke g, on said slide, the
operating lever e, mounted in said yoke and provided with flares or bevels to enable it
to pass over said projections in lifting, and the spring which holds said operating lever
up elastically to the face of the standard, as set forth.
4. In a lifting jack, the combination with the standard, the headed fulcrum studs
arranged in two rows thereon, as described, the extension slide mounted in said
standard, and the yoke g, on said slide, of the operating lever, pivotally mounted in
said yoke at a point between the rows of fulcrum studs, said lever being notched and
flared as described at the two points where it engages said studs, and the spring
which holds said lever up to said standard, as set forth.
Dated th: 00-31
1000
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.