Improvements in Lifting-jacks.
Year: 1899

page_text: Date of Application, 4th Apr., 1899-Accepted, 6th May, 1899
GOALL DRIE DIBUITIONAL
Improvements in Lifting-jacks.
I, CHARLES RENÉ PRÉVOST, of 52, Rue Montmartre, Paris, France, Manu-
facturer of Bottle-holders, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement:-
A lifting-jack according to this invention, although more especially designed
with a view to being employed as a carriage-jack for raising the axles of vehicles,
particularly motor road vehicles, so as to raise the wheels off the ground, as for
the purpose of cleaning, repairs, or examination, is, nevertheless, perfectly suit-
able for all the purposes for which actually existing jacks are commonly employed.
A jack according to this invention presents the advantages of requiring for
its operation only a comparatively small force and of being capable, in conse-
quence of the special arrangement of the mechanism for actuating it, of remaining
loaded in any position whatsoever into which it may have been put, without
comprising for this purpose either a rack and pawl arrangement or any such
supplementary retaining device.
For this purpose the mechanism for actuating the jack comprises a Worm
actuated by suitable means such as a crank and gearing with a worm-wheel, which,
by means of a pinion fixed to its shaft, raises or lowers, according to the direction
of rotation, given to the worm, a rack the upper end of which bears against the
object upon which it is desired to act.
In order that my invention and the way of performing the same may be clearly
understood I will describe it in detail with the aid of the accompanying draw-
ings, in which
Fig. 1 is a sectional side elevation of a jack according to this invention;
Fig. 2 is a vertical section corresponding to the line 2-2 of Fig. 3, with the
addition, on the head of the rack, of a bracket hanging down from, and laterally
to, this head to enable loads situated at a less distance from the ground to be
lifted, as in the case of ordinary jacks;
Fig. 3 is an elevation of the jack taken at right angles to Fig. 2 and from the
left hand thereof, the box being in section; and
Fig. 4 is a sectional elevation of an extension-piece enabling the jack to be
actuated, if necessary, at a certain distance off.
is the frame of the apparatus, which is suitably fixed to a base and in the
lugs c and d of which revolves a shaft e carrying a worm with one or more
threads and right or left handed as may be deemed useful or suitable and according
to requirements. The worm f gears into a suitable worm-wheel g keyed on a
transverse axle on which is fixed or formed a toothed pinion which gears into
a rack suitably guided at % and 7 so as to be capable of moving up and down
inside the frame a.
The shafte of the worm f ends in a portion el of square cross section upon
which is fitted a crank m which is kept in place by a set screw and by means
of which the worm f may be rotated as desired. It is obvious that instead of a

page_text: crank, a suitable lever with ratchet and pawl may be provided for rotating the
worm.
If, when the jack has been brought into the desired position in relation to
the carriage axle or other object on which it is desired to act, it is found that
access to the handle m is impossible or difficult, use is made of the extension-
piece which is shown in Fig. 4 and which consists of a metal rod o of any desired
length, solid or tubular, and having at one end a socket o¹ of square cross section
which fits on the square portion e' of the worm shafte whilst its other end carries
a portion o of square cross section intended to receive the crank m. It will be
easily understood that with an extension-piece of corresponding length, the jack
may in this way be actuated at any suitable distance off. It will also be easily
understood that, as the wheel y evidently cannot rotate the worm, the jack will,
when loaded, remain in any position without a retaining catch.
The rack is surmounted by a head p, which is preferably concave so as to
embrace easily the axles of vehicles, and especially, of motor road vehicles; but
this head may, of course, be made of any other shape more suited to the particular
purpose for which the jack may be intended.
To enable the jack to be used for loads situated at a distance from the ground
less than the minimum height of the apparatus, the head of the rack is pre-
ferably arranged, as is shown, moreover, in the drawing, so as to receive a bracket
(Figs. 2 and 3) which hangs down from and laterally to the head of the jack
and enables loads situated a short distance off the ground to be lifted, as in the
case of an ordinary jack.
A box r of suitable shape and fixed to the frame a by screws s, preferabiy
encloses the worm train in order to protect it against dust and the introduction
of foreign bodies liable to damage it.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I claim
is;-
1. A lifting-jack in which the motion is transmitted to the lifting-head by
means of a worm actuated by suitable means and acting on a worm-wheel which,
by means of a pinion keyed on its axle actuates a rack at the top of which is
formed the lifting-head, substantially as hereinbefore described and as shown in
the accompanying drawings, for the purposes specified.
2. A jack according to the preceding claim in which the worm is rotated by
means of a crank through an extension-piece. such as o, substantially as and
for the purpose specified.
Dail this 441 1
L
1 1000