Year: 1886

page_text: Date of Application, 12th July, 1886.
Complete Left, 5th Apr., 1887.
Complete Accepted, 6th May, 1887.
We JOHN SANDERS STEVENS and CHARLES GEORGE MAJOR Engineers of Janus
Works, Queen's Road Battersea in the County of Surrey do hereby declare the nature
of this invention to be as follows:-
The objects of our invention are the better utilization of the water pressure in lifts
working under a low head of water, and an increase of safety in suspended lifts.
The first part of our invention relates more particularly to hydraulic lifts in which
the cage is suspended, and the motive cylinder is placed vertically, but is in some
measure applicable to all hydraulic lifts.
In lifts with vertical cylinders it is usually convenient to arrange the motion of the
ram, or piston, to be the opposite of that of the cage; i.e. the ram descends while the
cago ascends.
In most ordinary cases the cylinder would be fixed entirely above the ground, and
the exhaust water would be delivered immediately beneath the ground level. The
plane of effect of the motive water would be at the top of the ram, which would be
about 2 times the length of stroke above the point of exhaust, & this portion of the
available head of water would be wasted.
Attempts have been made to avoid this loss of head by providing an excess of
counterbalance weight equivalent to the loss of head, to assist in lifting the load, and
then on the descending journey, to trust to the syphoning action of the exhaust pipe
to produce a partial vacuum equal to the lost head, which would so serve to rebalance
the excess counterbalance. Such an arrangement will however only work so long as
air is rigidly excluded. Should air be admitted, the syphon action is interrupted, &
the excess counterbalance prevents the descent of the cage. We provide an automatic
arrangement for the expulsion of air in the following manner. We attach to the
highest point of the supply pipe, or of the cylinder, a small pipe leading to an air-tight
chamber with two openings, one at the bottom for the above mentioned connecting
pipe, the other at the top opening into the atmosphere.
Each opening is closed by a suitable puppet or beating valve, both valves opening
inwards, and closing outwards, to prevent exit from the chamber. The valves act
therefore in reverse direction, and are both loosely connected to a float placed between
them, the lower valve hanging from the float, and the upper valve being supported by

page_text: it. The total length of the two valves together with the float and connexions, is such
that both valves cannot be simultaneously closed-if one is closed the other would be
about inch open. The chamber is made of some considerable capacity beyond that
requisite to receive the float. The action is as follows:-Assuming that the lift
cylinder & pipes are all charged with air, the weight of the float pulls the upper
valve down and leaves a free exit from the chamber.
Water under pressure is admitted to the cylinder, and as the air expulsion chamber
provides an exit at the highest point, all the air is blown through it, the pressure
opening the lower valve sufficiently for the purpose. The upper valve is made of
smaller area, and the float is heavy enough to hold this valve down against the
current.
When the water follows the air into the chamber, it raises the float till the upper
valve is closed, and farther exit is prevented, before all the air is expelled. The small
portion of entrapped air is then compressed to a density equivalent to the water
pressure. Now immediately any syphoning action, or partial vacuum is set up in the
systein, the small volume of compressed air in the chamber expands and forces the
water beneath it downwards through the connecting pipe, depriving the float of its
support, and closing the lower valve, but entrapping a considerable volume of water
above it. If now it is requisite to maintain the partial vacuum for some time, and the
lower valve should not be perfectly tight, the leakage through it will for a long time
be water only, and the partial vacuum is not impaired. On the other hand when the
upper valve is closed, any leakage past it would be air only, and would cause no
annoyance. If air should be accidentally admitted to the pipes or cylinder during
work, immediately the pressure at the base of the connecting pipe to chamber exceeds
the atmospheric pressure, such air will be forced up into the chamber, and will
escape through the upper opening until water follows and again closes the upper
valve.
This air expulsion arrangement is applicable to any lift or other apparatus where
there is alternate pressure and vacuum.
Another difficulty in connection with such lifts arises under the following
conditions:-
The starting valve is fixed close to the ground level, perhaps 20 ft. to 30 ft. below the
level of the inlet to the cylinder, and the connecting pipe contains a considerable
volume of water.
The valve is opened to exhaust for the descent of the cage. Some accidental impedi-
ment prevents the cage from descending, and its removal occupies several minutes
during which time the valve remains open.
Should then any air find its way into the pipe Letween the valve and the
cylinder, the pipe will quickly empty itself of water & become filled with air from
below.
Then when the cage is released there exists no control over its descent, till sufficient
water has passed out of the cylinder to refil the pipe. The cage may thus have virtually
fallen through several feet, and is ultimately pulled up with a shock very dangerous to
both passengers and machinery.
We prevent such an occurrence by the introduction of an automatic valve con-
structed as follows; and inserted in the pipe at its junction with the cylinder. A
small cylinder closed at both ends is fitted with two pistons, connected together by a
distance piece. The double piston is free to move from end to end of the small
cylinder, and when at the centre divides the cylinder into three chambers. The centre
Chamber is at all times in free communication with the pipe, and under normal
working conditions, also in free communication, by means of a port, with the lift
cylinder, the centre chamber thus forming a portion of the connecting pipe, and the
double piston is in equilibrium as regards the water passing through the centre
chamber. The chamber at one end is always in communication with the pipe by means
of a small passage; while the opposite end is similarly in communication with the
lift cylinder.
So long as the pressures in pipe and lift cylinder are equal, the piston is in

page_text: equilibruim as regards the two end chambers, and will not move. But if the pipe
has been emptied as described, and water is suddenly forced out of the lift cylinder,
the pressure in the end chamber connected to lift cylinder will exceed that in end
chamber connected to pipe; the piston will then be forced along the small cylinder,
till the port opening from lift cylinder is nearly but not quite closed, so putting
a check upon the lift immediately it commences to move, but avoiding the shock of a
complete stoppage. When the starting valve is reversed for lifting, the pressure in
the pipe will be greater than that in the lift cylinder, owing to the contracted port, and
the excess pressure will force the piston back into the normal position.
In a modification, a spindle is arranged to pass through one cover, for working the
valve by hand to keep it free. The spindle would be carried out at the lift cylinder
end, and would thereby disturb the equilibrium in such a manner as to ensure the
piston retaining its proper normal position, when the pressures in pipe and lift cylinder
are equal. Several modifications of the valve may be made but all based on the same
general idea.
The second portion of our invention consists of farther devices for insuring safety
in hydraulic lifts such as described, and other suspended lifts.
We suspend the cage by three or more ropes, chains, or other flexible media; three
are sufficient for the carrying out of our invention, but more may be used. In the
following description we refer to ropes only, but wherever the word "ropes" is used,
it is to be understood that we mean also chains, cords, bands, or any other flexible
connexions.
In the case of an ordinary hydraulic lift with multiplying cylinder, and in the case
of a suspended lift in which the ropes are coiled upon a barrel, each rope is separately
connected to the cylinder or to the barrel,-all are led over wheels at the top of the
lift well, and descend to the cage, either grouped or in isolated positions, but however
the three ropes may be arranged, ultimately two of them are carried down to one side
of the bottom of the cage, and one to the other. The two ropes are attached
one to each end of a rocking bar, fulcrumed at the centre, and secured to a short
spindle.
The bracket carrying the spindle is secured beneath the frame of cage, and serves
also to support it on that side. At the inner end of the spindle is secured a second
double ended rocking bar, standing vertically and at right angles to the first. Chains
or cords are secured to each end of the second rocking bar, and are carried round
small wheels keyed upon a shaft extending entirely across the bottom of cage, and
beneath it. The chains are secured to the wheels, so that whichever way the bars
rock, i.e. whichever chain is pulled, the shaft is revolved in the same direction. Keyed
to each end of the shaft is a gripping cam with varying radius and toothed surface,-
which cams when moved out of the normal position, grip the guides on both sides of
the cage, between themselves and projecting jaws secured to the frame of the cage.
In the normal condition the first or rope bar is horizontal, both ropes are of the same
length, and the cams are running clear of the guides. But if either rope stretches or
breaks, the opposite rope takes all the weight, pulls the bar out of the horizontal,
partially revolves the shaft, and throws the gripping cams into contact with the guides.
The surfaces of the cams are so formed, that once in contact, the weight of the cage
and its load only intensifies the grip.
The irregular form of the cams throws them out of balance, and would cause them
to fall into action when not required. This is prevented by a very light spring and
curb chain, which give way when the gear is required to act.
The preceeding is a complete safety gear, so long as either rope remains intact.
We connect with it, by means of the third rope, another arrangement designed to
act if all three ropes have broken, or if the third rope only has broken. The third
rope is taken down to the opposite side of the bottom of the cage, and secured to a
single armed lever secured to a spindle and supporting bracket, similar to that on the
side first described. On the inner end of the spindle is secured a second single
armed lever, from which a chain is carried to a wheel on the same shaft as described
in the first gear.

page_text: To the inner lever is also secured a strong tension spring, pulling in opposition to
the strain of the third rope. The latter is however allowed to preponderate, and pulls
its lever against a stop. If all the ropes break, or if the third rope only fails, the
spring on this side does what the surviving rope should do on the other, and thus a
second and independent safety gear is formed.
A third arrangement for throwing the gear into action, is sometimes provided in the
form of a hand lever and chain; the lever stands up inside the cage, and the chain
from its opposite end is carried to the cam shaft, so that a passenger may throw the
apparatus into action by hand from the interior of the cage. This is a safeguard in
case the controlling valve, or valve gear, may have failed, or should an excessive speed
be attained from any cause.
Several modifications of our invention suggest themselves. The chains may be
replaced by slotted links, the sheaves by levers, the inner rocking bars by cams and
slides, and so on through many mechanical equivalents; the limiting conditions being
that, the cam shaft must be capable of revolving even if the rocking bars and
spindles are stationary; that for reverse movements of the rocking bars the cam shaft
moves always in the same direction;-that the gear on either side must be capable of
independent action ;-and that the hand lever must be capable of giving motion to
the gear, without receiving motion from it when the latter is thrown into action by
other means.
In applying this portion of our invention to hydraulic lifts made in accordance with
our Letters Patent No. 4375 A.D. 1882, and No. 15953 A.D. 1884, we modify the
apparatus therein described as follows:
Instead of using a single chain attached to the press ram and actuating one chain
barrel and rope drum, we duplicate these portions of the machine. We attach two
chains to the press ram, each strong enough to do the whole work.
Each chain gives motion to one of two independent chain barrels, each barrel in
turn actuating an independent rope drum. To each drum is secured one of the ropes
of the first described safety gear.
The result is that not only is the failure of either rope provided for, but also the
failure of any key, chain, or attachment throughout the system, as there are two
independent courses of strain all the way from the cage to the press ram, and should
a failure occur at any point in either course, the unbalanced strain of the other course
throws the safety gear into action.
The third rope from the second safety gear is secured to either drum.
Either or all of the three ropes may be duplicated in any case if desired, and may
be arranged so that both ropes of a pair must break before the safety gear acts, or
they may be so connected, by means of a well known system of compound levers,
that every rope on one side of the cage shall take an equal strain, and the failure of
any one shall slacken back all the others, and cause the safety gear to act.
Dated this 12th day of July 1886.

page_text: JOHN SANDERS STEVENS & CHARLES GEORGE MAJOR, Engineers "Janus" Works
Queen's Road Battersea in the county of Surrey do hereby declare the nature of
this invention and in what manner the same to be performed, to be particularly
described and ascertained in and by the following statement :-
The objects of our invention are the better utilization of the water pressure in lifts
working under a low head of water, and an increase of safety in all suspended lifts.
The first part of our invention relates more particularly to hydraulic lifts in which
the cage is suspended, and the motive cylinder is placed vertically, but is in some
measure applicable to all hydraulic lifts.
In lifts with vertical cylinders see fig. 2, it is usually convenient to arrange the
motion of the ram, or piston, to be the opposite of that of the cage; i.e. the ram
descends while the cage ascends. In most ordinary cases the cylinder would be fixed
entirely above the ground, and the exhaust water would be delivered immediately
beneath the ground level.
The plane of effect of the motive water would be at the top of the ram, which would
be about 2 times the length of stroke above the point of exhaust, and this portion of
the available head of water would be wasted. Attempts have been made to avoid this
loss of head by providing an excess of counterbalance weight equivalent to the loss
of head, to assist in lifting the load, and then on the descending journey, to trust to
the syphoning action of the exhaust pipe to produce a partial vacuum equal to the lost
head, which would so serve to rebalance the excess counterbalance.
Such an arrangement will however only work so long as air is rigidly excluded.
Should air be admitted, the syphon action is interrupted, and the excess counter-
balance prevents the descent of the cage. We provide an automatic arrangement for
the expulsion of air in the following manner.
We attach to the highest point of the supply pipe A, fig. 1. or of the cylinder,
a small pipe B leading to an air tight chamber C with two openings, one at the
bottom D for the above mentioned connecting pipe, the other at the top E opening
into the atmosphere. Each opening is closed by a suitable puppet or beating valve,
both valves opening inwards, and closing outwards to prevent exit from the chamber.
The valves act therefore in reverse directions, and are both loosely connected to ä
float F placed between them, the lower valve G hanging from the float, and the upper
valve H being supported by it. The total length of the two valves together with the
float and connexions, is such that both valves cannot be simultaneously closed;-
if one is closed the other would be about inch open. The chamber is made of some
considerable capacity beyond that requisite to receive the float. The action is as
follows. Assuming that the lift cylinder and pipes are all charged with air, the
weight of the float F pulls the upper valve H down and leaves a free exit from
the chamber C. Water under pressure is admitted to the cylinder, and as the air

page_text: expulsion chamber C provides an exit at the highest point, all the air is blown
through it, the pressure opening the lower valve G sufficiently for the purpose.
The upper valve H is made of smaller area, and the flout F is heavy enough to hold
this valve down against the current. When the water follows the a'r into the
chamber C, it raises the float F till the upper valve H is closed, and farther exit
is prevented, before all the air is expelled. The small portion of entrapped air is then
compressed to a density equivalent to the water pressure. Now immediately any
syphoning action, or partial vacuum is set up in the system, the small volume of com-
pressed air in the chamber C expands and forces the water beneath it downwards
through the connecting pipe A, depriving the float F of its support, and elosing the
lower valve G, but entrapping a considerable volume of water above it.
If now it is requisite to maintain the partial vacuum for some time, and the lower
valve G should not be perfectly tight, the leakage through it will for a long time be
water only, and the partial vacuum is not impaired.
On the other hand when the upper valve H is closed, any leakage past it would be
air only, and would cause no annoyance. If air should be accidentally admitted to
the lift pipes or cylinder during work, immediately the pressure at the base of the
connecting pipe A to chamber exceeds the atmospheric pressure, such air will be
forced up into the chamber C, and will escape through the upper opening E until
water follows and again closes the upper valve H.
This air expulsion arrangement is applicable to any lift, or other apparatus where
there is alternate pressure and vacuum.
Another difficulty in connexion with such lifts arises under the following
conditions.
The starting or controlling valve I, fig. 2, is fixed close to the ground level, perhaps
20 to 30 ft. below the level of inlet to the cylinder J, and the connecting pipe K
contains a considerable volume of water.
The valve I is opened to exhaust for the descent of the cage L. Some accidental
impediment prevents the cage from descending, and its removal occupies several
minutes during which time the valve I remains open. Should then any air find its
way into the pipe K between the valve I and the cylinder M, the pipe K will quickly
empty itself of water and become filled with air from below. Then if the cage L is
released there exists no control over its descent, till sufficient water has passed out of
the cylinder M to refill the pipe K. The cage may thus have virtually fallen through
several feet, and is ultimately pulled up with a shock very dangerous to both passengers
and machinery.
We prevent such an occurrence by the introduction of an automatic valve fig. 3
constructed as follows, and inserted in the pipe K at its junction with the cylinder M.
A small cylinder N.closed at both ends is fitted with two pistons 0, 0¹, connected
together by a distance piece. The double piston is free to move from end to end of
the small cylinder N, and when at the centre divides the cylinder into three chambers.
The centre chamber is at all times in free communication with the pipe K, and under
normal working conditions, is also in free communication, by means of a port P, with
the lift cylinder M, the centre chamber thus forming a portion of the connecting
pipe K, and the double piston 0, 0¹, is in equilibrium as regards the water passing
through the centre chamber.
The chamber R at one end is always in communication with the pipe K by means
of a small passage S; while the opposite end T is similarly in communication with the
lift cylinder M by means of passage S¹.
But
So long as the pressures in pipe K and lift cylinder M are equal, the piston 0, 0¹,
is in equilibrium as regards the two end chambers R and T and will not move.
if the pipe K has been emptied as described, and water is suddenly forced out of the
lift cylinder M, the pressure in the end chamber T connected to lift cylinder M will
exceed that in the end chamber R connected to pipe K, the piston 0, 0¹, will then be
forced along the valve cylinder N, till the port P opening from lift cylinder M is
nearly but not quite closed, so putting a check upon the lift immediately it commences
to move, but avoiding the shock of a complete stoppage.

page_text: When the starting valve I is reversed for lifting, the pressure in the pipe K will be
greater than that in the lift cylinder M, owing to the contracted port P, and the excess
pressure will force the piston 001 back into the normal position.
In a modification a spindle U is arranged to pass through one cover for working
the valve by hand to keep it free. The spindle would be carried out at the lift
cylinder end, and would thereby disturb the equilibrium in such a manner as to ensure
the piston 0 0¹ retaining its proper normal position, when the pressure in pipe K
and lift cylinder M are equal.
Fig. 4 shews the automatic check valve in the other extreme position, with port P
nearly closed.
Several modifications of the valve may be made but all based on the same
general idea.
For instance, the spindle U may be omitted and piston O made rather, smaller than
piston O, giving the latter the preponderance of power. Or the valve may be made
as in fig. 5, in which equivalent parts have the same letters as in other figures. In
this form, while water is flowing from K to M, or at any time when pressure in K is
not less than that in M, the valve O must be held off its seat by virtue of the dis-
turbance of equilibrium caused by trunk U. But should pressure in M exceed by
any considerable amount that in K, the excess pressure in chamber N will force the
valve O over, nearly closing the passage.
The amount of difference of pressure which is desired to move the valve will
determine the relative proportions of O and U..
We do not intend these valves to entirely close, but merely to constrict the
passage, so that the cage may slowly descend to the bottom, and there discharge
its load.
The automatic valves described, or modifications of them, are also used by us to
moderate the speed of the descent of cage, in case the supply main should burst, or
when from any other cause the pressure in pipe K should be unduly reduced.
The second portion of our invention consists of farther devices for insuring safety
in hydraulic lifts such as described, and other suspended lifts.
We suspend the cage by three or more ropes, chains, or other flexible media; three
are sufficient for the carrying out of our invention in its ordinary form, but more
may be used. In the following description we refer to ropes only, but wherever the
word "ropes" is used, it is to be understood that we mean also chains, cords, bands,
or any other flexible connexions. In the case of an ordinary hydraulic lift with
multiplying cylinder, and in the case of a suspended lift in which the ropes are coiled
upon a barrel, each rope is separately connected to the cylinder or to the barrel,-all
are led over wheels at the top of the lift well, and descend to the cage, either grouped
or in isolated positions, but however the three ropes may be arranged, ultimately two
of them are carried down to one side of the bottom of the cage, and one to the other.
The two ropes see fig. 6 are attached one to each end of a rocking bar A, fulcrumed
at the centre, and secured to a short spindle B. The bracket C carrying the spindle B
is secured.beneath the frame of cage D, and serves also to support it on that side.
At the inner end of the spindle B is secured a second double ended rocking bar E,
standing vertically and at right angles to the first bar A.
Chains or cords F F¹ are secured to each end of the second rocking bar E, and are
carried round small wheels G keyed upon a shaft H extending entirely across the
bottom of cage, and beneath it.
The chains F F are secured to the wheels G, so that whichever way the bars A
and E rock, i.e. whichever chain is pulled, the shaft H is revolved in the same
direction. Keyed to each end of the shaft H is a gripping cam I, I', with varying
radius and toothed surface, which cams, when moved out of the normal position,
grip the guides J, J¹, on both sides of the cage, between themselves and projecting
jaws K secured to the frame of the cage D. In the normal condition the first, or
rope bar A, is horizontal, both ropes are of the same length, and the cams I, I', are
running clear of the guides J, J¹. But if either rope stretches or breaks, the opposite
rope takes all the weight, pulls the bar A out of the horizontal, partially revolves the

page_text: shaft H, and throws the gripping cams I, I' into contact with the guides J, J¹. The
surfaces of the cams are so formed, that once in contact, the weight of the cage and
its load only intensifies the grip. The irregular form of the cams throws them out
of balance, and would cause them to fall into action when not required.
This is prevented by a very light spring Land curb chain M, which give way when
the gear is required to act. We sometimes dispense with the spring L, and curb
chain M, by constructing the cams with a counterbalance weight sufficient to reverse
the effect of their deformity, and hold them out of contact. Or such a counterbalance
weight may be separately secured to the shaft H.
The preceeding is a complete safety gear, so long as either rope remains intact.
We connect with it, by means of the third rope, another arrangement designed to
act if all three ropes have broken, or if the third rope only has broken, see fig. 7.
The third rope is taken down to the opposite side of the bottom of the cage D, and
secured to a single armed lever N secured to a spindle O and supporting bracket P,
similar to that on the side first described.
On the inner end of the spindle O is secured a second single armed lever R, from
which a chain S is carried to a wheel T on the same shaft H as described in the first
gear. To the inner lever R is also secured a strong tension spring U, pulling in
opposition to the strain of the third rope. The latter is however allowed to pre-
ponderate, and pulls its lever N against a stop V. If all the ropes break, or if the
third rope only fails, the spring U on this side pulls the cams I, I¹ into action, and
thus a second. and independent safety gear is formed.
A third arrangement fig. 8 for throwing the gear into action, is sometimes provided
in the form of a hand lever W, and chain X; the lever stands up inside the cage,
and the chain from its opposite end is carried to the cam shaft, so that a passenger
may throw the apparatus into action by hand from the interior of the cage. This is
a safeguard in case the controlling valve, or valve gear, may have failed, or should an
excessive speed be attained from any cause. Several modifications of these arrange-
ments are possible without departing from our invention, as for instance, the
chains F F may be replaced by slotted links, and the sheaves G, by levers as in
fig. 9. Or again, the inner rocking bars E and R, and the chains F F¹, may be
replaced by cams and slides as in fig. 10; and so on through numerous mechanical
equivalents, the essential conditions for the carrying out of our invention being, that
the cam shaft must be capable of revolving even if the rocking bars and spindles are
stationary, that for reverse movements of the rocking bars the cam shaft moves
always in the same direction,-that the gear on either side of the cage must be
capable of independent action, and that the hand lever must be capable of giving
motion to the gear, without receiving motion from it when the latter is thrown into
action by other means. In some cases we find it preferable to replace the projecting
jaws K fig. 6, with cams, so that the guides J J are gripped between two cams.
The additional cams may be hung freely, so that they only roll when brought into
contact by the action of the first cams; or they may be keyed to a second shaft Y
fig. 11, the two shafts being linked together, so that positive and simultaneous action
must occur on the part of both cams. In some cases it is convenient to apply our
invention to lifts suspended by two ropes only, and we then carry it out in the
following manner.
One rope is led down to each side of the cage. A rocking shaft a. fig. 12, crosses
the bottom of cage, and has keyed to it at one end a short horizontal one armed
leyer b, and to this one rope is secured. On the other end of the shaft is a second
and longer lever c, standing in the reverse direction, and to this the second rope is
secured.
On the same shaft a, is keyed a vertical double armed lever as in fig. 6, from which
chains pass to sheaves on a cam shaft, all as previously described. With this
arrangement the stretching or breaking of either rope, compelling the shaft a to
partially revolve, will cause the gear to act as already explained. But owing to the
difference in the lengths of the levers b, and c, the strain on the two ropes would be
unequal.

page_text: To redress this inequality, a strong spring d is coupled to that end of the vertical
double armed lever which will allow the spring to pull against the lightly loaded
rope, and relieve the heavily loaded one, and by adjusting the spring, the strains
upon the ropes may be practically equalized. Under these conditions (1) should
either rope stretch, the opposite rope would act virtually as if the levers were of
equal length and no spring existed; (2) should the short lever rope break, the long
lever rope by virtue of its greater leverage will overpower the spring, and throw the
gear into action; (3) should the long lever rope break, the short lever rope would be
assisted by the spring to throw the gear into operation; (4) should both ropes break
simultaneously, the spring being uncontrolled will of itself throw the gear in, this
being the object of its introduction. The handle could be attached as before. In
this manner we obtain the full advantage of the duplicate safety gear, while using only
two ropes.
We so arrange the line of strain of the spring relatively to the lever to which it is
coupled, that in case (2) the power of the spring decreases as the sound rope pulls the
lever over; while in cases (3) and (4) the spring becomes more powerful as it pulls
the lever back. This arrangement may also be used by bringing both ropes down on
one side of the cage, uniting c and 6 into one double armed lever keyed to one end
of the shaft a all other parts remaining as before. We prefer this when the cage
cannot be rigidly braced in all directions.
Although the preceeding descriptions have all referred to safety gears attached to
the bottom of the cage, it is obvious that they may all equally well be attached to the
top of the cage, retaining the arrangement practically as described. A more simple
method of doing this in the case of a light hand lift with two ropes is shewn in
fig. 13, in which the ropes e e¹ are attached to the opposite ends of a double lever f,
which is extended at both ends. From the extremities of the lever two curb
ropes g, g, are taken to a sheave h secured to the cam shaft i carrying cams j j¹.
Then the stretching or breaking of either lifting rope by throwing lever fout of its
normal position, will cause the cams to partially revolve, and grip the guides k, k¹,
between themselves and the jaws l, l'.
We sometimes modify this arrangement as in fig. 14, in which the lifting ropes e, e¹,
are similarly attached to the opposite ends of a double lever f, which is in contact with
two triggers m, m², secured to the same shaft which carries the cams j j¹.
In this case any movement of the lever f, caused by the stretching or breaking of
either rope, must serve to force one of the triggers back, partially revolve the shaft.
and cause the cams to grip the guides k k¹ as described. By an obvious modification
the same gear may be arranged to trip two cams which would grip one guide between
them as in fig. 15. In applying this portion of our invention to hydraulic lifts made
in accordance with our Letters patent No. 4375 A.D. 1882, and No. 15953 A.D. 1884,
we modify the apparatus therein described as follows.
Instead of using a single chain attached to the press ram and actuating one chain
barrel and rope drum, we duplicate these portions of the machine.
We attach two chains to the press ram, see fig. 16, each strong enough to do the
whole work.
Each chain n, n¹ gives motion to one of two independent chain barrels o, o¹, each
barrel in turn actuating an independent rope drum p p.
To each drum is secured one of the ropes of the first described safety gear.―The
result is that not only is the failure of either rope provided for, but also the failure
of any key, chain, or attachment throughout the system, as there are two independent
courses of strain all the way from the cage D to the press ram M, and should a failure
occur at any point in either course, the unbalanced strain of the other course throws
the safety gear into action.
The third rope from the second safety gear is secured to either drum, or may be
omitted, and device in fig. 12 used.
Either or all of the three ropes may be duplicated in any case if desired, and may
be arranged so that both ropes of a pair must stretch or break before the safety gear
acts, or they may be so connected, by means of a well known system of compoundl evers,
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page_text: that every rope on one side of the cage shall take an equal strain, and the failure of
any one shall slacken back all the others, and cause the safety gear to act.
Having now particularly described and ascertained the nature of our said invention,
and in what manner the same is to be performed, we declare that what we claim is :-
(1) In a hydraulic suspended lift the use of an air expulsion trap as and for the
purposes described.
(2) In a hydraulic suspended lift, the use of an automatic check or governing valve
as and for the purposes described.
(3) In a suspended lift with two or more lifting ropes, the use of safety apparatus,
held out of action by the opposing pull of the various ropes, but thrown into action
by the partial or entire failure of either rope; as, and for the purposes described.
(4) In connexion with a safety apparatus for a lift, the application of hand gear
for throwing the apparatus into action at will, from within the cage as described and
illustrated.
Datad this mah law of Annil 1207