IMPROVEMENTS IN DIFFERENTIAL GEARING APPLICABLE TO LIFTING JACKS, CRANES, WINDLASSES, AND OTHER PURPOSES
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents, with his Petition, on the
21st May 1868.-A communication from abroad by Michel Loup,
of 13, Boulevart St. Martin, Paris.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN DIFFERENTIAL GEARING APPLICABLE
TO LIFTING JACKS, CRANES, WINDLASSES, AND OTHER PURPOSES," to be as
follows:-
This Invention relates to improvements in differential gearing ap-
plicable to lifting jacks, block and fall, and other tackle, windlasses,
cranes, regulators of looms, presses of all kinds, steering apparatus,
and generally to all machines in which the power is increased by the
reduction of the speed.
This improved apparatus has the advantage of enabling two different
speeds to be obtained without complicating the essential parts. The
differential or lower speed serves to produce power and enable the

page_text: motion of the apparatus to be arrested under the weight at any point
forming the normal condition of the apparatus, while the higher speed
is intended for placing the lifting gear at any desired point. In this
case the apparatus is arranged as in ordinary, the weight acting on
the winch according to the relative positions of the levers.
The apparatus is arranged in the same manner in all its applications,
and I will here only explain its more important features as applied
to lifting jacks' tackle and lastly to windlasses and cranes, reference
being had to the accompanying Drawings, Figure 1 of which shows
a front view, and Figure 2 a side view of the improvements applied
to a lifting jack, while Figures 3 and 4 show details of the mechanism
in side view and section. The letters of reference apply. to all the
Figures.
The apparatus consists of a ring C having twenty-eight teeth on its
interior and rigidly fixed to a disc D, which is also fixed to a
principal shaft E by keying or otherwise, or it may be formed in one
with said shaft. A second wheel F having twenty-seven teeth is
placed within the ring of teeth C so as to gear therewith. This wheel
turns freely on an eccentric G which is mounted on a pivot H formed
on the end of shaft E, Figures 1 and 2. The eccentric G forms part
of a lever I carrying the winch handle J by which the apparatus
is operated; another lever K forming the fulcrum of the apparatus
terminates in a disc L enclosing the gearing. This disc has a six-
sided or it may be a circular opening, in which is received a pro-
jection on wheel F so as to firmly unite the two parts together with
the addition of rivets. The other end M of lever K is provided with
a bolt for disconnecting the parts, as will be herein-after described.
The nut and collar a on the end of pivot H simply serve to keep
the eccentric G. and wheel F in position without exerting any pressure
thereon. It should be remarked that the lever K has a slight up-and-
down motion (being mounted on the eccentric) during the differential
movement.
Action of the Apparatus.-By rotating winch handle J the eccentric G
formed thereon is caused. to turn on pivot H, and as the eccentric
forms in its turn the axis of toothed wheel F, the latter is also carried
round and gears with the teeth of ring C; this motion tends to turn
the wheel F on eccentric G, which is however prevented by the lever K

page_text: connected thereto, the end M of which is retained in position by the
bolt before mentioned. Thus the wheel F partakes in the motion of
the eccentric without revolving therewith, the upper teeth always
remaining in that position, and the others the same during the
differential motion. In this manner the ring. C and shaft E on which
it is mounted will be caused to turn.
In the Drawings the wheel C is provided with twenty-eight teeth
and wheel F with twenty-seven, so that at each revolution of the winch
handle J the ring C is advanced a tooth or 7th of a turn. Thus
the six-toothed pinion N carried by the shaft E will make the 28th
of a turn for each revolution of the winch, and the rack O of the
jack operated by said pinion N will be raised or lowered in the
same proportion, viz., th of the circumference of pinion N.
I will here describe the mode of stopping the apparatus under the
weight. The pressure exerted by the weight raised either on the
foot P of the rack or on its upper end Q is brought to bear on lever K,
which I term the fulcrum firmly attached to the framing at M. The
weight acts successively on pinion N, shaft E, disc D, and ring C, which
latter by means of its teeth (as seen in Figure 3) acts on the wheel F,
and consequently on lever K fixed to same. The strain brought to bear
on K is transformed into pressure on the eccentric, which pressure
would theoretically have the effect of turning the eccentric G on
pivot H, but as the eccentricity is very slight the friction will be
neutralized, and the winch will remain at the point where it is
released.
The second or greater speed of the jack is produced by the aid of
disconnecting gear, which may be adapted to all the applications of the
apparatus, as I will now proceed to describe. I have above mentioned
that levér K during the differential motion has a slight up-and-down
movement produced by the eccentric and equal to double the eccen*
tricity of the latter. In order to permit of the free motion of K during
the differential movement, its end M is provided with a bolt P' received
in an elongated opening S made in a plate O solidly fixed to the jack.
In this manner the lever K will readily rise and fall in the slot S, but
is prevented from turning on the eccentric. The bolt P¹ is fitted to
work in the hollow boss M of lever K so as to permit of its alternately
projecting on the side of framing R and winch J. In order to readily

page_text: and surely effect this action of the bolt P' a lever V is passed through
it in the manner shown fixed at point i, its opposite end forming a hand-
hold, another lever T terminated by a spring bearing on K is provided
with a stud entering holes made in the bolt for the purpose of regulating
the position of the latter.
In
The following is the mode of operating the disconnecting gear.
order to render the bolt free to engage either with the winch or with
the framing, the lever is pulled until it comes in contact with the
stop at this moment the stud is released from the bolt which
is thus freed; after this the bolt may be brought to any desired position
by the aid of the handle V.
In order to obtain either speed in the jack I proceed in the
following manner :-For the lower or differential speed the apparatus
is arranged, as shown in Figures 1 and 2, with the bolt in the boss M
engaging in the slot S of plate O fixed to the jack. In this position
the lever K is fixed and the winch I free, which may then be turned
in one direction or the other, in order to raise or lower the rack
without danger of the winch running back whatever may be the
weight carried by the apparatus. In order to obtain the higher speed
the winch handle J is brought to position and the lever T moved to
the left for the purpose of disconnecting the bolt P', after which it is
pulled outwards from the framing by the aid of lever V so as to move
The handle
the bolt out of S and bring it in gear with the winch J.
is then released and the differential arrangement thrown out of opera-
tion; in this manner the two levers I, K, are. solidly united and move
together. Thus on turning the winch both levers I, K, will also
turn and directly act on pinion N by the aid of the toothed wheel F
gearing in C and thus act directly on the rack. In this manner one
turn of J will raise or lower the rack six teeth corresponding to the
number of teeth of pinion N, and by giving it several turns (according
to the number of teeth of the rack) it may be raised or lowered to the
. full extent. In order to again obtain the differential speed I proceed
in the same manner to bring down the lever V so as to bring the bolt
into gear with the plate S. This disconnecting gear possesses three
properties 1st, that of fixing lever K to framing R for obtaining the
differential speed; 2ndly, of uniting levers I and K for obtaining the
higher speed; 3rdly, of fixing levers I and K to the framing when the

page_text: In order to effect the latter result it is simply necessary to provide the
bolt P' with three notches instead of two. The two extreme notches
give the results before mentioned, while the intermediate one is used
when the apparatus is out of action by connecting the bolt with S as
well as J. The other parts of the jack present no features of novelty.
1, 2, are metal plates forming the casing which are firmly secured to
the wood R; a ring V₁ serves for lifting the apparatus and placing it
in position.
Application of the Apparatus to Pulley Tackle.-The mechanism
above described with reference to the lifting jack is also applicable to
tackle, similar letters answering for corresponding parts. However in
the case of a block and fall I have shown a modified arrangement of the
eccentric which is formed in one with the shaft H. The latter is in
consequence made in three parts, consisting of a head c (for preventing
the wheel F from slipping off) eccentric G and shaft H, as seen in
Figures 5 and 6. Figure 5 being a face view of the block and fall,
and Figure 6 a transverse section of same. A grooved pulley X is
keyed to shaft H so as to turn therewith, said pulley forming a substitute
for the lever I of the lifting jack. A toothed wheel V" is keyed to the
hollow shaft E, carrying a chain Y having a hook Z at its lower end
to which the weight to be raised is attached, while a second-hook A, A,
serves to attach the apparatus at any point, the other end n of the chain
moves freely up and down. The chain B, B, carries the whole of the
parts. A friction roller C, C, serves as a guide for the chain Y so as to
maintain the vertical position of the apparatus while raising the weight.
Motion is imparted to the apparatus by the endless cord D, D, carried
on the grooved pulley X, a guide bar O being applied to prevent the cord
escaping. The disconnecting gear indispensable in the lifting jack
may be dispensed with as being difficult of application to the tackle,
which is invariably hung at a great height, I therefore simply use a
slot as in the jack arrangement or an oscillating lever S, taking care to
bevil off the points of contact of the oscillating axes to prevent friction
whether lubricated or not. I may also substitute the following arrange-
ment instead of the above in a block and fall. I make the endless
chain Y of greater or less length according to requirements, and employ
a double independent hook Z, as seen in Figure 7, so that it may be

page_text: attached at any point of the endless chain. In this manner instead of
reversing the action in order to lower the hook, it is detached from the
chain and placed at the height desired, hence increased simplicity in the
mechanism is attained with a saving of time. The groove of pulley X
is provided with V-shaped projections to prevent the cord D, D, from
slipping thereon. The direction of motion of the apparatus. is shown
by the arrows in Figure 5.
Application to Windlasses, Cranes, and other Purposes.-This improved
apparatus may be readily applied to the above purposes, for which end
it is simply necessary to replace the plates 1, 2, of the jack by a frame
suited to the purpose required, and substitute a drum for the pinion on
which to wind the chain or cord of the windlass, crane, or other
apparatus. The hollow shaft E, Figure 6, is employed if it is desired to
use two winch handles, one on the side of X and the other on the side c;
or the shaft, Figure 2, may be used if one winch only is required. In
both cases the same arrangement before described is adopted for pro-
ducing the different speeds, or the arrangement, Figures 5 and 6, if one
speed only is required.
In applying the improvements to windlasses, the pulley X is replaced
by ordinary gearing driven by a pinion placed above. This arrangement
possesses the advantage of enabling the drum to be placed nearer the
ground and the winch handle or handles at breast height.
From the excessive freedom of motion of the various parts of the
apparatus there may be some slight tendency in the winch to run back
when released, which would thus act as a fly wheel, and especially if the
differential motion is equal only to a fifteenth or one tooth in fifteen.
In order to obviate this objection I may fix a spring on the lever I acting
on a friction roller mounted on shaft E between the nut and the washer.
It will be understood that either of the arrangements described may be
employed in the several applications of this Invention. The apparatus
may also be modified in arrangement so as to communicate by means of
the eccentric the motion direct to wheel C, Figure 3, in which case
the disc D would be placed in a central position in front and be driven
by the eccentric, which wheel F would be fixed to shaft E.
The diameter and number of teeth of wheels C, F, may vary, but the
inner wheel should always have a less number of teeth than the ring.
In ordinary, the winch handle is detached from the jack when trans-

page_text: porting it from place to place, and the same may be the case with the
improved apparatus of this Invention. However as the eccentric
attached to the winch should preferably remain in position I may if
desired separate the one from the other and fit the winch on a six or
other sided projection formed on the eccentric, fixing them together by
means of a key or nut.