Improvements in or relating to Jacks.
Year: 1894

page_text: Date of Application, 9th July, 4804
Complete Specification Left. 5th Ar.. 1895-Accepted. 18 h May. 1995
Complete Specification Left. 5th Ar.. 1895-Accepted. 18 h May. 1895
Improvements in or relating to Jacks.
I, JAKOB SILBEREISEN of Neustift near Passau in the Empire of Germany,
Manufacturer do hereby declare the nature of this invention to be as follows:-
This invention relates to jacks and consists in providing them with devices by
which they can be automatically fixed or prevented from returning when bearing a
load, thus increasing the safety of handling them, by means of certain brake
mechanism; such jacks are moreover adapted for the alternate raising and lowering
of loads without necessitating the removal by hand of the pawl of the ratchet
intended for preventing the return and its subsequent re-insertion.
On the axle of the crank is fitted a double cone brake, that is to say two cones
apex to apex adapted to be pressed from opposite ends of the axle against the
inverted conical sides of a fixed sleeve which may be one of the bearings of said
axle. The one of these cones carries a screw threaded sleeve on which the other
engages so that by turning one of said cones with regard to the other the cones may
be caused to approach or recede. This turning is effected by means of a brake
block on a lever which may either be moved against the coue by hand through a set
Ecrew, or by taking advantage of the displacement of the principal toothed wheel of
the rack gearing when the crank is moved or at rest respectively, the bearings of
this wheel being elongated for this purpose.
The pressure of the brake shoe on the cone arrests the latter so that the continued
turning of the crank axle causes the coues to be screwed together or apart according
to the direction of motion.
To supersede the removal and insertion of the ratchet pawi by hand, there is
fitted behind the pawl a swinging lever adapted to lift the pawl out of gear with
the ratchet and this lever is operated by a pin guided in a slot and engaging with
the lever. This pin is carried by a spring or other device frictionally connected
with one of the wheels of the gear in such a way that when the crank is revolved
to lift the jack rack bar the friction of that part of the gear aforesaid carries the
pin and with it the lever into such position that the ratchet and pawl gear with one
another, while upon reverse action of the handle or crank the pin is carried into its
position for disengaging the pawl by the reversed movement of said gear.
Dated this 9th day of July 1894.
R. HADDAN,
Agent to Applicant.
1 JAKOB SILBEREISEN of Neustift near Passau in the Empire of Germany,
Manufacturer, 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 jacks and consists in providing them with devices by
which they can be automatically fixed or prevented from returning when bearing a

page_text: load, thus increasing the safety of handling them, by means of certain brake
mechanism; such jacks are moreover adapted for the alternate raising and lowering
of loads without necessitating the removal by hand of the pawl of the ratchet
intended for preventing the return and its subsequent re-insertion.
On the axle of the crank is fitted a double cone brake, that is to say, two cones
apex to apex adapted to be pressed from opposite ends of the axle against the
inverted conical sides of a fixed sleeve which may be one of the bearings of said
axle. The one of these cones may be fixed to the screw threaded axle on which the
other is screw threaded to engage so that by turning one of said cones with regard
to the other the cones may be caused to approach or recede. This turning is
effected by means of a brake block on a lever which may be moved against the cone
by hand either through a set screw or automatically by taking advantage of the
displacement of the principal toothed wheel of the rack gearing when the crank is
moved or at resi. respectively, the bearings of this wheel being elongated for this
purpose.
The pressure of the brake shoe on the cone arrests the latter so that the continued
turning of the crank axle causes the cones to be screwed together or apart according
to the direction of motion.
To supersede the removal and insertion of the ratchet pawl by hand, there is
fitted behind the pawl a swinging lever adapted to lift the pawl out of gear with
the ratchet and this lever is operated by a pin guided in a slot and engaging with
the lever. This pin is carried by a spring or other device frictionally connected
with one of the wheels of the gear in such a way that when the crank is revolved to
lift the jack rack bar the friction of that part of the gear aforesaid carries the pin
and with it the lever into such position that the ratchet and pawl gear with one
another, while upon a sufficient reverse action of the handle or crank the pin
is carried into its position for disengaging the pawl by the reversed movement of
said gear thus permitting in such case a lowering of the jack without disengaging
the pawl by hand.
In the annexed drawing the brakes shown in Figs. 1 & 2 in longitudinal section,
and in Fig. 3 in lateral view, are to be engaged and disengaged by hand, whilst the
brake, which is shown in Figs. 4 and 5, acts automatically.
In Figs. 1 and 2 rear journal box y of the crank shaft z forms a double cone
(Fig. 2); the crank shaft has a conical end r, and is screw threaded to receive the
brake cone w displaceable towards the double cone; the brake cone w usually rests
against the set nuts of the crank shaft and participates in every movement of the
latter. The brake cone is provided with a circular groover, into which the
brake shoe suspended at u can be inserted to be pressed against the brake cone.
For this purpose is provided the thumb nut 7 (Fig. 1) rotarily journalled in
the spring bow s. The thumb nut engages the screw bolt p, firmly secured to the
brake shoe.
For moving the rack bar, the brake shoe is lifted off from the brake cone by a
turning of the thumb nut, so that the crank shaft with brake cone and wheel gearing
can be set into rotary motion. When the rack bar is to be secured in any desired
position, the thumb nut q is turned to introduce the brake shoe into the circular
groove of the brake cone w so as to press said brake shoe firmly against the brake
The pressure may be regulated according to the load by turning the thumb
nut, so that the spring bows is brought into greater or less tension.
cone.
On descending of the load together with the rack bar the wheel gearing and
consequently also the crank shaft z rotate in the reverse sense.
The brake cone wo
however is not allowed to follow this movement, because of its being fixed by the
brake shoe. The screw thread on the crank shaft causes displacement of the rotary
cone, in an axial direction towards the rear journal box, so that onto its double
cone on the one hand the brake cone and on the other the conical end of the
crank shaft will be pressed, whereby further turning of the latter is prevented.
It is evident that the brake shoe must be hung so as to be enabled to follow the
slight displacement of the brake cone in axial direction.

page_text: If the rack bar is required to run back loosely, the brake shoe t is removed from
the brake cone by means of the thumb nut q.
In Figs. 4 and 5 the braking and releasing respectively is effected automatically.
In this case the brake shoe t forms a bent lever, the arm t¹ of which is by means of
a spring pressed against the underside of the shaft of the large cog-wheel a¹..
The bearings of the latter are constructed in such a way as to allow of a slight
displacement of said shaft in vertical direction. When the rack bar is unburdened,.
the shaft of the wheel a¹ is on the one hand by the spring 2, acting on lever arm t',
and on the other band by means of a second spring o (in the drawing a leaf spring)
suitably fixed on the front plate of the casing, held upwardly in the position shown
in dotted lines in Fig. 4. On raising the burden, that is to say, when the wheels
are rotated in the opposite sense of the arrows (Fig. 4), the large wheel a¹ keeps
approximately the upper position, because the cogs of the gearing, arranged on the
crank shaft z will tend, on turning, to lift in the opposite sense to the arrow of the
large cog wheel a and to hold said large wheel in its upper position in co-operation
with the springs t³ and o.
On descending of the rack bar, when charged, its cogs exert a downward pressure
upon the pinion m, on the shaft of the large cog wheel, so that the spring pressure
is overcome and the shaft of the large cog wheel pressed downward (see Figs. 4.
and 5 drawn in full lines). The brake shoe is thus moved into the position
shown in full lines, that is to say, said brake shoe is pressed into the circular
groove of the brake cone, whereby the conical brake is actuated as before
described. After removing the load, the springs lift the shaft of wheel a¹ and set.
the brake shoe out of action, so that the rack bar can be moved downward.
Fig. 6 shows the safety mechanism when the rack bar is locked by the paw),.
and Fig. 7 shows the same when the rack bar recedes, in this case the pawl being
released. Figs. 8 and 9 are detail views. Below the pawl a lever c is pivotally
arranged, one arm of which effects the release of the pawl, while its other arm is
guided by a pin c. This latter causes the movement of the lever c from the wheel
gearing in the following manner :
The large cog wheel a¹ (Fig. 8, section and Fig. 9 front view) receives in a
chamber or recess of the front side a spring which lies against the wall of this
chamber. Spring & receives the pin c¹ which through a slot f of the covering plate.
of the wheel gearing projects into a slot, made in the lever c.
The slot serves to limit the movement of the pin c' of the spring b', so that the
spring during the rotation of the wheel a¹ slides upon the walls of the chamber, but,
on changing the rotary direction, is to the extent of the length of the slot f carried
along with the wheel a¹.
Supposing that crank, lever, pawl and rack bar are in position of Fig. 5, pawl b
engaging the ratchet wheel. If the jack is now wound up, the pawl slides over the
teeth of the ratchet wheel; consequently a turning of the crank in the opposite
direction can at most be effected to the extent of the length of one tooth's pitch.
This small amount of rotary motion is sufficient to impart to the whole wheel
gearing a reverse movement. The consequence thereof is, that also the wheel a'
will execute a rotary motion in the reverse sense and during this movement will
carry with it the spring to the extent of the length of the slot f, so that the pin c¹
arrives out of the position of Fig. 6 into the position shown in Fig. 7. During this
action the pin c¹ causes the lever c to turn; this lever then releases the pawl, so that.
now a return motion of the jack can take place. If then the rotary movement
changes again, the lever c will be sent back into its previous position by means of
the pin c¹, and the pawl falls automatically (by its own weight) against the rack
wheel.
Such automatic engaging and releasing of the pawl offers great safety and
advantage to the use of the jack, since any person actuating the jack may safely
and continually work the crank with both hands, while with jacks in present use, for
alternately lifting and lowering the load, the pawl must be engaged or released.
respectively by hand.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :
1. An improved safety device in rack and pinion jacks, consisting of a conical
brake, acting upon the crank shaft, the brake cone w of which brake, connected to
the crank shaft by means of a screw thread, on descending of the charged rack bar
is adapted to be secured against turning by means of a brake shoe t, actuated either
by hand or automatically, and is consequently by the screw thread of the rotating
crank shaft displaced thereon, so that said brake cone simultaneously with the
conical head of the crank shuft, presses itself against the bi-conical journal box
of the crank shaft, thus producing a braking action upon the latter and consequently
upon the rack bar.
2. The construction for automatically placing the brake shoe on to the brake cone
during the descending of the charged rack bar, said rack bar being adapted to press
down the axle of the gearing engaging into the said rack bar and likewise the arm t¹
of the brake shoe resting beneath the axle, which latter is displaceable in its
bearings in a vertical direction and held upwards by means of springs.
3. An automatic safety device in lifting-jacks, having a lever c which, by means
of a pin c, actuated by the wheel gearing, is on altering the rotary motion of the
jack, displaced in such a manner, that the lever e¹ will lift the pawl out of ratchet
wheel, and on again winding up will allow the pawl to automatically fall upon and
engage the ratchet wheel.
;
4. The combination of the pin c', guided in a slot f of the covering plate of the
wheel gearing, with the gearing by means of a spring 6, fixed on said pin, which
spring lies against the walls of a chamber, in the wheel a¹ of the gearing and on
changing the rotary direction moves with said wheel to the extent of the length of
the slot f, substantially as and for the purpose set forth.
1361 1
1 1007
R. HADDAN,
Of the Firm of Herbert Haddan & Co.,
18, Buckingham Street, Strand, London, W.C., Agent to Applicant.