Improvements in Lifting Jacks.
Year: 1891

page_text: Date of Application, 28th Apr., 1891-Accepted, 6th June, 1891
COMPLETE SPECIFICATION.
Improvements in Lifting Jacks.
We, THOMAS MAXON, EDWARD C. BOYER, and THOMAS STANILAND of
Dayton in the County of Montgomery and State of Ohio, United States of
America, Inventors and Manufacturers, 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 lifting jacks and has for its object the provision of a
strong durable jack of few yet efficient parts not likely to get out of order and in
all respects perfectly adapted for the uses to which mechanism of this class is
applied. To this end the invention consists in the jack and the parts thereof as
hereinafter described and claimed.
In the drawings,
Fig. 1 shews a view of the jack in side elevation:
Fig. 2 a vertical central section :
Fig. 3 a view similar to Fig. 2, to illustrate the structure of the standard, for
which purpose the movable parts are omitted; and
Fig. 4 a detail perspective view of the lifting dog, and a portion of the operating
lever in dotted lines to shew the mode of connecting these parts.
Referring to the drawings by letters, A. designates a suitably shaped standard
cast in one piece, preferably, and provided with a base B of appropriate design.
Within an opening that extends from top to bottom of the standard, is a lifting
bar C capable of vertical movement therein, and having at its lower end, on the
front side, a lifting foot r, which latter moves in a suitable slot c¹ in the standard
and when the bar is at its lowest position, is seated or contained within a recess c"
provided for its reception in the base B.
This lifting bar is made hollow from end to end and contains a reinforcing or
strengthening rod or bar C¹ extending its entire length. Said rod may be secured
therein by any suitable means as by providing at its lower end a head C₁ and
screw-threading its upper end and placing thereon a nut D. The face of the latter
is serrated and it constitutes a lifting or supporting surface at the upper end of the
lifting bar. While we prefer this construction of lifting bar which is similar to
that shown in Letters Patent of the United States No. 395,161 granted to one of
us the said Thomas Maxon Dec. 25 1888, we of course do not intend to be limited
to the use of a bar so constructed.
The rear face of the lifting bar is provided with or formed into teeth c²
preferably, as shewn, ratchet in shape, which extend substantially from top to
bottom, with which similarly shaped, but reversely arranged teeth e on the front
face or edge of a lifting dog E are adapted to engage, and through the medium of
which when said dog is properly operated, said lifting bar may be raised, as is
usual in devices of this description.
The dog E is located at a point about midway between the top and base of the
standard Å being situated in a recess or space between the sides of the latter. At
or near its vertical centre, it has a transversely extending circular opening in which
is seated an eccentric F adapted to be moved or oscillated upon. a pivot pin or
bolt whose outer ends are journalled in openings in the lower ends of swinging
links G, depending, at a slight angle of inclination from a vertical line, from a
transverse pivot pin or bolt 9 placed near the top of the standard A. Likewise
journalled on-the bolt i, in a space left between each side of the dog E and the
links G, are the arms hh, of the operating lever H, whose end is forked or
bifurcated to form said arms. The latter are connected with the eccentric by

page_text: means of a ping which is passed transversely through all three, and, it is to be
noted, at such a point that when the operating lever is in a horizontal plane said
pin will be in a plane above the latter, preferably such an one that a line drawn
through said pin and the pivot pin i will stand at an angle of 45°. This construction,
as will be readily understood enables the power or force exerted on the lever H to
be applied most nearly in the direction of the load to be lifted, as well as insures
that the dog will be forced and held in engagement with the lifting bar. Preferably
the teeth of the dog are located above the plane of the eccentric, so that there is
a pushing action against the lifting bar, rather than a lifting as would be the case
were such teeth in a lower plane. It is also to be observed that the shape and
relative situation of the arms h, are such as to completely cover the sides of the
eccentric, which, in consequence of its position in the lifting dog, is thus completely
housed.
Passing through the upper end of the lifting dog is a pin or bolt e¹ whose ends
project beyond the sides of the same, and into slots a formed in each side of the
standard A, which slots both in their vertical and horizontal dimensions are greater
than the diameter of said pin. A similar pin el passes through the lower end of
the dog, and into slots a', a', in each side of the standard that these latter, unlike
the former, have width just equal to the diameter of the pin, although vertically
being greater, and at their lower portions are deflected at an angle in a direction
rearward away from the lifting bar. These two sets of pins and slots form guides
for the lifting dog E and its vertical movements. The lower pair excepting as to
their inclined portions are parallel with the lifting bar and one side of the upper
pair, that adjacent to the bar, is also parallel, so that when said dog is to be
moved upward, it will be compelled to move in a line parallel with the line of
movement of the lifting bar. When the dog is to be moved downward, as to get
a new purchase to raise the bar higher, the superior width of the upper recesses or
slots, will enable the upper pin and dog to move sufficiently to permit the
disengagement of the teeth of the dog from those of the lifting bar, said dog
vibrating on the lower pin, or if lowered enough to pass the latter into the
deflected portion of the guiding slot, such will operate to move said dog bodily
away from the lifting bar.
It is of course not necessary that the guide pins should be provided as above
described, for instead, they may be simply studs projecting from the sides of
the dog.
To hold the lifting bar to the position to which it may be raised, we preferably
pivot upon the same bolt from which the links G depend where said bolt passes
between the sides of the standard, a pawl K having teeth G' to engage with the
teeth of said bar. This pawl is automatically caused to engage with such teeth
by means of a flat spring which at one end bears against the underside of the
pawl, and at its other upon an adjacent piece a extending between the inner sides
of the standard sides. Such pawl may be the same as that shown in the herein-
before referred to patent, and may be operated and locked out of engagement
with the lifting bar teeth in a similar manner.
Our device is simple in construction yet powerful and certain in its action.
Owing to the position of the cam relative to the operating lever, the power applied
is most advantageously employed, while in conjunction with the swinging links and
the guiding devices, the movements of the lifting dog into and out of engagement
with the lifting bar, are positively and quickly effected.
For convenience in transporting our jack we provide on opposite sides pivoted
handles M M, by which it can be readily picked up and carried.
Preferably the lower portions of the upper guide slots are the widest and the
rear walls are inclined toward the top portions, either on a curved or a straight
line, so that the guide pins will be engaged thereby and compel the lifting dog to
move towards the lifting bar should such engagement become necessary because of
failure of the other parts to cause the dog to have such movement.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is:-
1. The combination of a standard, a toothed lifting bar therein, a holding dog
pivoted on the standard and normally engaging the said lifting bar, a lifting dog
working in a vertical slot in the side of the standard and provided with teeth
engaging the lifting bar, means for vertically guiding this dog, an eccentric
journalled in an opening formed in this dog about midway between its ends, an
operating lever provided with a fork the arms of which embrace the dog and
eccentric, a horizontal pivotal bolt i passed through the eccentric and the arms of
the fork and extended out laterally therefrom, swinging pivotal links connecting
the ends of this bolt to a point on the standard, and means, such as a pin g, for
locking the eccentric to the arms of the fork, substantially as described.
2. In combination with a standard having upper and lower guide slots, the lifting
dog having pins at its upper and lower ends to engage said slots, the horizontal
dimension of the upper slots being greater than the diameter of their pins, and the
lower portions of the lower slots being deflected outwardly, an operating lever
connected to said lifting dog, and a lifting bar, substantially as and for the purpose
shown.
3. In combination, a standard having upper and lower guide slots, a lifting bar
having teeth, a lifting dog also toothed, an eccentric journalled in said dog, an
operating lever secured to said eccentric, swinging links carrying the pivot for the
latter and the operating lever, and the pins at upper and lower parts of the dog
engaging the before mentioned slots, said pins and slots operating to guide said
dog so as to permit a vertical and a horizontal movement, substantially as shown.
Dated this 99th day of Anvil 1901
THOMAS MAXON,
By L. W., per F. B.
EDWARD C. BOYER,
By L. W., per F. B.
THOMAS STANILAND,
By L. W., per F. B.