Improvements in Screw Lifting Jacks.
Year: 1893

page_text: Date of Application, 6th June, 1893
Complete Specification Left, 20th Feb., 1894-Accepted, 28th Apr., 1894
PROVISIONAL SPECIFICATION.
Improvements in Screw Lifting Jacks.
1 GEORGE TANGYE Director of Tangyes Limited, of Cornwall Works, Soho
in the County of Stafford Engineers do hereby declare the nature of this invention
to be as follows :-
My invention has for its object to reduce to a minimum the friction between the
head of the lifting screw jack and the top of the screw working in the said head
in such jacks as have fixed nuts or screw boxes in which the screw is made to
rotate by means of a ratchet or other lever. Also to reduce to a minimum the
friction in screw lifting jacks in which the nut or screw box is rotated, the screw
having no rotary motion.
In making a screw lifting jack of the first described kind I connect the top of
the rotating screw with the non-rotating head carried by it in the following manner.
Instead of making the flat top of the screw bear against a flat surface in the
recess in the head in which the said screw engages I leave a space or chamber
between the two flat parts and on the top of the screw I fix a cupped or U leather
or other packing washer, the mouth of the packing leather being upwards. I make
a small hole either in the axis of the head or in the side of the head the said hole
opening into the space or chamber described. Through the said hole oil or grease
or other liquid or semi-liquid or solid lubricant (such as plumbago) may be intro-
duced for filling the said chamber the hole by which the lubricant was introduced
being closed by means of a tight fitting screw.
In working the lifting jack made as described the top of the screw does not
bear against the top of the recess in the head in which it engages, but bears against
and rotates upon the under surface of the lubricant with which the chamber is
filled. The friction between the two flat surfaces, namely, the top of the screw
and the top of the recess in the head of the jack is thereby avoided and the only
friction in the line of the axis of the screw is between the top of the screw and
the underside of the bearing cushion formed by the lubricant.
In making lifting jacks with rotating nuts or screw boxes I form on the underside
of the shoulder of the nut or screw box (which shoulder bears and rotates upon the
case of the jack) an annular ring or projection which said annular ring or projection
takes into and works in an annular recess or groove of corresponding figurei n the
top of the case of the screw jack. The said annular recess is of greater depth
than the annular ring or projection on the nut or screw box which takes into it
and the space between the ring or projection and bottom of the recess. is filled
with lubricant. The said space may contain a cupped or U leather packing
washer with its mouth downwards bearing against the annular ring or projection or
the space may contain a second cupped or U leather washer with its mouth
upwards the last named washer bearing against the bottom of the annular groove
in the case of the jack. The lubricant is introduced through a small hole in the
case of the jack which hole after the lubricant has been introduced is closed by a
tight fitting screw.
The shoulder of the nut or screw box is not in contact with the top of the jack
case so that the whole of the pressure in the working of the jack is borne by the
lubricant contained in the annular groove in the case of the jack.

page_text: The application of my invention to screw lifting jacks of types other than those
described differs in no essential respect from its application to the jacks hereinbefore
described.
Dand hit of T1002
W. T. WHITEMAN,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Screw Lifting Jacks.
I GEORGE TANGYE, Director of Tangyes Limited, of Cornwall Works, Soho,
in the County of Stafford, Engineers do hereby declare the nature of my invention
and in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
My invention has for its object to reduce to a minimum the friction between the
bead of the lifting screw jack and the top of the screw working in the said head in
such jacks as have fixed nuts or screw boxes in which the screw is made to rotate
by means of a ratchet or other lever. Also to reduce to a minimum the friction in
screw lifting jacks in which the nut or screw box is rotated, the screw having no
rotary motion.
In making a screw lifting jack of the first described kind I connect the top of
the rotating screw with the non-rotating head carried by it in the following manner.
Instead of making the flat top of the screw bear against a flat surface in the recess
in the head in which the said screw engages, I leave a space or chamber between
the two flat parts and on the top of the screw I fix a cupped or U leather or
packing washer, the mouth of the packing leather being upwards. I make a small
hole either in the axis of the head or in the side of the head, the said hole opening
into the space or chamber described. Through the said hole oil or grease or other
liquid or semi-liquid or solid lubricant (such as ozokerit or plumbago) may be
introduced for filling the said chamber, the hole by which the lubricant was
introduced being closed by means of a tight fitting screw.
By this construction the top of the screw does not bear against the top of the
recess in the head in which it engages, but bears against and rotates upon the
under surface of the lubricant with which the chamber is filled.
In making lifting jacks with rotating nuts or screw boxes I form on the underside
of the shoulder of the nut or screw box (which shoulder bears and rotates upon the
case of the jack) a ring or annular projection which said ring or annular projection
takes into and works in an annular recess or groove of corresponding figure in the
top of the case of the screw jack. The said annular recess is of greater depth than
the ring or annular projection on the nut or screw box which takes into it, and the
space between the ring or projection and bottom of the recess is filled with
lubricant. The said space may contain a cupped or U leather packing washer
with its mouth downwards bearing against the ring or annular projection; or the
space may contain a second cupped or U leather washer with its mouth upwards,
the last named washer bearing against the bottom of the annular groove in the
case of the jack. The lubricant is introduced through a small hole in the case of
the jack wh ch hole after the lubricaut has been introduced is closed by a tight
fitting screw.
The shoulder of the nut or screw box is not in contact with the top of the jack
case so that the whole of the pressure in the working of the jack is borne by the
lubricant contained in the annular groove in the case of the jack.
The application of my invention to screw lifting jacks of types other than those
described differs in no essential respect from its application to the jacks hereinbefore
described.

page_text: I will now proceed to describe with reference to the accompanying drawing the
manner in which my invention is to be performed.
Figure 1 represents in vertical section, a screw lifting jack having a rotating
screw and a fixed nut or screw box, the said jack containing my improvements.
Between
a is the rotating screw working in the fixed screw box or nut g at the top of the
case h and is the ratchet in which is placed the lever bar for operating the jack
as usual; b is the non-rotating head of the jack carried by the screw a.
the top of the screw a and the recess in the head a space or chamber is left for
receiving the cushion of grease or lubricant c; d is the cupped leather packing on
the top of the screw a between which packing d and the top of the recess in the
head the lubricant cushion c is situated. The liquid or semi-liquid lubricant for
filling the chamber or recess in the head is introduced into the said chamber,
after the end of the screw and packing have been placed in it, by the axial hole in
the said head, the said hole being closed after the lubricant has been introduced
into the said chamber by the tight fitting screw e as represented.
When a solid lubricant such as that known in commerce as ozokerit or plumbago
or other solid lubricant is employed it is preferred to use it in the form of a
tablet, the said tablet being introduced into the space or chamber in the head b
of the jack before the said head is connected to the screw a.
It will be seen by an examination of the drawing that when the lifting
jack Figure 1 is worked by the ratchet at f the top of the screw a does not
bear against the top of the recess in the head in which it engages but bears
against and rotates upon the surface of the cushion of grease or lubricant c with
which the said recess is filled. The friction between the two flat surfaces, namely
the top of the screw a and the top of the recess in the head b of the screw jack is
avoided and the only friction in the line of the axis of the screw a is between the
top of the screw and the underside of the cushion of grease or lubricant c.
Figure 2 represents in vertical section a lifting screw jack with a rotating
nut or screw box and a non-rotating screw containing my improvements: a is the
non-rotating screw having a lifting claw a² at bottom; g is the rotating screw box
operated by the ratchet f as usual.
In this arrangement the underside of the screw box 92 is provided with the
annular projection g³ which takes into and works in the annular recess or groove in
the expanded top of the case h of the jack; d is the inverted cupped leather
packing bearing against the ring or projection g³ and c is the cushion of lubricant,
liquid or solid, filling the space between the packing d and the bottom of the recess
in the head of the jack case as seen in the drawing. Or the recess for receiving
the lubricant cushion may be formed in the manner represented in Figure 3 and
instead of one cupped packing, two cupped packings marked d and d² arranged in
the manner represented in the said Figure 3 may be employed. The liquid or
semi-liquid lubricant is introduced into the recess in the head of the case by the
side hole at e closed by a screw pin. When solid Inbricant is used it is introduced
into the annular recess in the head of the case before the ring or annular
projection 93 of the rotating screw box g² is fitted in the said annular recess.
these arrangements it will be seen that the shoulder of the screw box or screw
nut 9' is not in contact with the top of the jack case, the whole of the pressure in
the working of the jack being borne by the lubricant cushion c contained in the
annular recess in the said case.
In
Figure 4 represents in vertical section and Figure 5 in end elevation a traversing
screw jack containing my improvements. In this kind of jack the rotating screw
box or nut g, worked by the ratchet at f, rises and falls upon the fixed screw a.
The said screw box 9' is formed into a cylindrical case for covering the screw a
and protecting it from injury. The top of the rotating screw box 9' is recessed for
receiving the stem on the underside of the head 6 of the jack, the bottom of the
stem being provided with a ring packing d of the kind hereinafter described and
the space between the said packing d and bottom of the recess in the top of the
screw box g being filled with liquid or solid lubricant c as herein before described;

page_text: k is the traversing screw and is the traverse base of the jack. By means of a
screw stop n at the base of the screw nut g coming against the shoulder o of the
fixed case h, the said screw nut is prevented from rising beyond the normal lift of
the jack and from being screwed off the screw a.
Figure 6 represents another screw lifting jack somewhat similar to the jack last
described but with the traverse base omitted. In this screw jack, rotatory motion
is communicated to the screw box 92 by a bevil wheel p³ on the ratchet axis f
gearing with a bevil wheel p working on the top of the screw box 92, the motion of
the said bevil wheel p being transmitted to the screw box g² through the medium
of one or more flat surfaces on the screw box which engage with corresponding
projections on the inner face of the bevil wheel p. A rotary and vertically sliding
motion is thereby given to the screw box 92. The bevil wheel p is prevented from
rising by the projection q on the case of the jack. The packing and lubricant
cushion and other parts of this modified jack are the same as corresponding parts
of the jack represented in Figures 4 and 5 and are marked with the same letters
of reference.
Figure 7 represents another arrangement in which the rising and falling screw
box has only a sliding motion, the lifting claw g* working in a longitudinal slot in
the jack case.
In this arrangement the cushion or bearing of oil or lubricant e is
situated in a recess at the base of the jack, and the ring-packing d is placed on the
bottom of the rotating screw a. The screw a is driven by the pair of bevil
wheels p², p worked by the ratchet axis at f. The sliding screw box g² carries at
top the head b. An air hole at t permits the screw a to descend firmly upon the
lubricant cushion or bearing c.
Figure 8 represents in front elevation partly in section and Figure 9 in end
elevation a screw jack containing my improvements, to be used for straightening or
bending bars and the like. In this kind of jack the body or case h of the jack has
a nearly semi-circular figure and its ends are furnished with claws n, n which are
engaged with the bar or article to be operated upon; a is the fixed screw and g² the
tubular or protecting screw box working upon the said screw. To the screw box g²
the non-rotative head is fitted for bearing upon the bar or article, the packing
ring d and lubricant c being introduced between the rotating screw box g² and
non-rotating head 6 as herein before described. The screw parts in Figures 8
and 9 are the same as corresponding parts in Figures 4 and 5 excepting that they
are inverted.
For shearing or punching purposes, the head b in the screw box is furnished with
shear blades or a punching tool and die.
When I use a solid lubricant cushion, I prefer to employ a solid washer or ring
of leather or other hard non-metallic material in place of the cup leather packings
described and represented in Figures 1, 2 and 3. A washer or ring of this kind is
represented in Figure 10. This washer or ring is slit or divided at s to facilitate
its passage over the end of the head b into a groove or neck before the said end of
the head is placed in the recess in the jack. By the use of a packing consisting of
a split solid washer as described, the head b of the jack with its packing may be
removed together from the recess in which the said head works.
Having now particularly described and ascertained the nature of my invention
and the manner in which the same is to be performed I declare that I claim
as my invention ;-
The Improvements in Screw Lifting Jacks hereinbefore described and illustrated
in the accompanying drawing; that is to say, the combination with the end of the
rotating screw or with the rotating screw box or screw nut of the various types of
screw jacks described and illustrated and with the head or part against which the
said rotating screw or rotating screw box or screw nut works, of a liquid or semi
liquid or solid lubricant cushion or bearing and a cupped packing or solid ring
packing for the purpose of reducing the friction between the rotating part of the
screw jack and the head or portion against which the rotating part works, the parts

page_text: of the screw jacks being so modified as to fit them to receive the said lubricant
cushion or bearing and packing substantially as described and illustrated also the
combination of the lubricant cushion or bearing with screw jacks having internal.
or protected screws substantially as described and illustrated.
Dated the Seventeenth day of February 1894.