Improvements in Cranes.
Year: 1887

page_text: COMPLETE SPECIFICATION.
Improvements in Cranes.
1. WILLIAM HANCE RIDGWAY, of Coatesville, in the County of Chester, in the
State of Pennsylvania, one of the United States of America, Mechanical Engineer, do
hereby declare the nature of the said 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 relates to that class of cranes in which a vertically movable jib is
employed, the inner and outer ends of said jib being supported by means of ropes or
chains passing over suitable pulleys, and connected to a hoisting device on the post of
the crane, the objects of my invention being to dispense with the use of a special or
separate counterbalance for the jib, to prevent uneven strain on the hoisting device,
to limit the extent of movement of the jib, to cushion the hoisting device, and generally
to improve and renier more effective than usual, the construction and operation of the
crane.
On the accompanying drawings:
Fig. 1. represents a side view of a crane constructed in accordance with my
invention.
Fig. 2 represents an end view of the same, looking in the direction of the arrow,
Fig. 1. but without the supplementary cylinder.
Figs. 3, 4, and, 5, represent enlarged views of parts of the structure, illustrating
details.
Fig. 6. represents a perspective diagram showing one of the features of my
invention; and
Figs. 7, to, 11, represent views illustrating modifications of certain features of the
Invention..

page_text: A, is the hollow post of the crane, which consists of opposite side bars, a, secured
at their upper ends to a head block, b, and at their lower ends to a base block, d, said
head and base blocks being provided with suitable projecting pivot pins, c, the lower
of which is adapted to a hearing in a plate, c', the upper pin being adapted to any
convenient bearing, so that the post of the crane is free to swing on a vertical
axis.
Secured to and projecting outwardly at an angle from said post, A, is the arm, B,
of the Crane, the outer end of which is connected to the head block, b, by suitable
stay rods, this arm being, like the post, composed of opposite side bars, so as to
provide a central opening for the reception of the vertically movable jib, D, of the
crane.
The inner end of the jib, D, is supported by a chain, g, which passes around a
pulley, g', free to turn on a shaft, h, the latter being adapted to bearings, h', on the
post, A, and the outer end of the jib is supported by a chain, i, which passes round a
pulley, i, at the outer end of the arm, B, and is connected to a bar, j, to which are
also connected the ends of two chains, k, the latter passing round pulleys, k¹, also free
to turn on the shaft, h.
By this means, a downward pull upon the inner ends of the chains, 9, and, k, will
cause the vertical lifting of the jib, D, of the crane, said jih descending as the inner
ends of the chains are permitted to rise.
Various means have heretofore been devised for operating supporting chains so as
to effect the raising and lowering of the jib of a crane, one of the commonest plans
being to connect to a suitable windlass or winch on the post of the crane the inner
ends of two chains, the opposite ends of which are connected, respectively to the
inner and outer ends of the jib; and another plan is to connect the chains to the rod
of a piston adapted to a fixed cylinder carried by said post; but these plans are
objectionable because they necessitate the use of a heavy weight on the inner ends of
the chains in order to counterbalance the weight of the jib.
I operate the jib by means of steam or hydraulic pressure, but I reverse the con-
struction ordinarily adopted when such power is used, and employ a fixed piston, M¹,
and piston rod, M, in combination with a movable cylinder, N, the upper end of
which is connected to the inner ends of the hoisting chains of the jib.
By this means, the weight of the hoisting cylinder itself is available as a counter-
poise for the movable jib, hence the usual extra counterbalance weights are dispensed
with, and the structure is simplified and cheapened and otherwise improved by reason
thereof.
When steam pressure is used, I prefer to have it act through the medium of a
volume of water or other liquid, a supplementary cylinder, P', being located adjacent
to the post, A, of the crane, and being provided with steam inlet and exhaust
pipes, m, m³, a liquid conveyer pipe, n, and a valved drain pipe, n', the cylinder, P,
being in the first instance filled with water or other liquid, so that the admission of
steam through the pipe, m, into the upper end of the cylinder, P, will drive the
liquid therefrom and through the pipe, n, while on cutting off the flow of steam
through said pipe, m, and exhausting the steam through the pipe, m³, the liquid is
drawn back through the pipe, n, and into the cylinder, P.
The base block, d, of the crane post carries a flanged collar, p, secured to the lower
end of the hollow piston rod, M, said base block having two passages, s, and, t, the
passage, s, being formed in the body of the block, and the passage, t, in the pivot.
The liquid conveying pipe, n, passes through the base plate and through the
passage, t, and said pipe is in communication with the passage, s, through a bent
pipe, . provided with a suitable stuffing box, v', so that the swinging of the
crane post on its axis will not interfere with the free flow of the liquid to and
from the hollow piston rod, all of the joints being readily accessible for inspection
and repairs.
A stop block, a, on the post, A, serves as a rest for the inner end of the jib, D,
when the latter is at the limit of its downward movement, and the downward move-
ment of the outer end of the jib is simultaneously arrested by a stop block, a¹, which

page_text: is carried by the outer end of the arm, B, and serves as a seat for a bumper block. a
on the chain, i
In order to prevent jar when the jib reaches the limit of its upward movement, a
dash pot, e, secured to the flanged collar, p, receives the projecting stuffing box, w',
of the cylinder, M, as the latter descends, the stuffing box fitting the dash pot so
snugly as to confine the air therein and form a cushion.
The mouth of the dash pot is flared, and the stuffing box is tapered to insure the
proper engagement of the parts, and the openings in the base of the dash pot which
receive the stems of the confining bolts are larger than said stems, so as to permit
any desired lateral movement of the said dash pot (see Fig. 3).
In order to permit the ready levelling of the jib of the crane, when said level has
been disturbed by uneven wear or stretch of the chains, or from other causes, screw
connections, R, are provided between the supporting chains, g, and, , and the inner
and outer ends of the jib, although only one of these connections may be used if
desired, and in order to permit the proper centering of the pulleys, g', ¹, in respect
to the cylinder, N, the shaft, H, is adjustable in its bearings by means of set screws, 12,
as shown in Fig. 5.
The piston, , which I prefer to use is constructed in the manner shown in Fig. 4,
the shell, S, of the piston being connected to the hollow hub, S', by means of arms, T,
so as to permit the free flow of fluid from the hollow piston rod to the space beneath
the piston, the underside of the shell being movided with an angular flange, " of
flexible material, the outer lip of which is caused, by pressure, to bear firmly against
the inner side of the cylinder, N, in order to prevent leakage.
As a further precaution against leakage, the piston is provided with packing, y,
compressed by means of a follower, W. which is acted upon by nuts, a², adapted to
stud holts, u, projecting upward from the shell of the piston.
My invention may be carried out, however, without the use of the hollow piston
and piston rod for instance, in Fig. 7, I have shown a modified construction of crane
in which the piston rod is solid, the connection between the cylinders. N, and, P, being
effected by means of a flexible tube, n².
In a structure of the character described, it is important that the strain shall be
evenly distributed upon the cylinder, N, irrespective of the position of the load upon
the jib, D, otherwise, lateral twisting or straining of the cylinder will result when the
load is nearer one end of the jib than the other.
For this reason, I use the double equidistant chains, k, as a means of connecting
the outer chain, i, to the cylinder, so that the strain on said cylinder due to weight at
the outer end of the jib, is exerted at equal distances on each side of the centre of the
cylinder, while weight at the inner end of the jib exerts a direct central strain on the
cylinder, owing to the central connection of the chain, g
By this means, not only is unevenly distributed weight on the jib prevented from
laterally straining or swaying the cylinder, but such additional stability is imparted
thereto as to correct any such tendency as might arise from the sudden swinging of
the crane.
This arrangement of chains is also available in those cranes in which the cylinder
is fixed and the piston rod movable, and my claim on this feature of my invention is
intended to cover the latter construction as the equivalent of that shown.
Various arrangements of chains may be adopted within the scope of my invention
for instance, in Fig. 8 I, have shown chains, k, more widely separated than in Figs. 2,
and, 6, and in Fig. 9. I have shown a double chain connection for each end of
the jib.
In all of these cases, however, the chains from each end of the jib are symmetrically
disposed with reference to the centre of the hoisting device, that is to say, when a
single chain is used at one end of the jib, it is connected directly to the centre of the
hoisting device, and when two chains are used their connections are diametrically
opposite and equadistant from the centre of the hoisting device, so that precisely the
same strain is exerted on each side of the centre of the latter.

page_text: The chains may be double throughout the entire length from the cylinder to the
jib, if desired, double pulleys in this case being provided at the outer end of the
arin, B. The construction shown in Figs. 2, and, 6, is, however, preferred.
Strain on the cylinder might be equalized in a measure, when but two chains are
used, by adapting said chains to sprocket wheels, such as shown in, Fig. 10, for
instance, these wheels being secured together, so as to be incapable of independent
movement, either by securing them to the shaft, h, and permitting the latter to turn,
or by securing the wheels together and permitting them to turn on the shaft.
The use of sprocket wheels is, however, objectionable, hence, the multiple chain
connection is preferred.
It will be evident that ropes may be used in place of chains, if desired, except when
the sprocket wheels are employed.
Where the swinging of the crane is not desired, the framework of the crane may
consist of opposite fixed posts, serving as guides for the jib and carrying the
suspension and guide pulleys, as shown, for instance, in Fig. 11.
Having now particularly described and ascertained the nature of my said Inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The combination of the framework of the crane, the vertically movable jib and
its suspending chains, a cylinder connected to said chains, and a fixed rod, with a
piston contained in said cylinder, whereby the cylinder serves to counterbalance, or
partially counterbalance the weight of the jib, substantially as hereinbefore
described.
2. The combination of the framework of the crane, the vertically movable jib and
its suspending chains, the cylinder connected to said chains, a fixed piston contained
in said cylinder, and a hollow piston rou, through which the motive fluid is introduced
into the cylinder beneath the piston, substantially as hereinbefore described.
3. The combination of the framework of the crane, the vertically movable jib, the
actuating cylinder, piston and piston rod forming a hoisting device, a chain or chains
connecting one end of the jib to said hoisting device and exerting a central pull
thereon, a chain or chains connecting the other end of the jib to the hoisting device,
and means whereby said second chain or chains is also caused to exert a central puli
upon the said hoisting device, substantially as hereinbefore described.
4. The combination of the post of the crane, the vertically movable jib, the cylinder,
piston and piston rod, forming the hoisting device, and suspension chains connected
to the opposite ends of the jib and having three or more points of connection with
said hoisting device, the chains from each end of the jib being symmetrically disposed
with reference to the centre of the hoisting device and exerting the same strain on
each side of said centre, substantially as hereinbefore described.
5. The combination of the post of the crane, its projecting arm and vertically
movable jib, the suspension chains or ropes therefor, the actuating cylinder, a stop
block on the post of the crane for supporting the inner end of the jib when it is down,
and a stop block on the arm of the crane, forming, when the jib is down, a bearing
for a block on the chain which supports the outer end of the jib, substantially as
herein before described.
6. The combination of the hollow piston rod and the movable cylinder, with the
piston consisting of a shell with hollow hub and arms, a flanged packing strip on the
underside of the piston, and a packing follower on the upper side of the same, sub-
stantially as herein before described.
7. The combination of the framework of the crane, the vertically movable jib, the
hoisting device, suspension chains connecting said device to the opposite ends of the
jib, and an adjustable connection whereby the levelling of the jib can be effected,
substantially as hereinbefore described.
8. The combination of the framework of the crane, the vertically movable jib, the
actuating cylinder, the suspension chains, pulleys therefor, a pulley shaft, and means

page_text: for adjusting the latter in a direction transversely to the cylinder, so as to properly
centre the pulleys in respect to the said cylinder, substantially as hereinbefore
described.
9. The combination of the framework of the crane, the vertically movable jib, the
suspension chains, the actuating cylinder, the fixed piston and its rod, and the dash-
pot free to move laterally, and adapted for the reception of a projection on the
cylinder substantially as hereinbefore described.
Dated this 10th day of December 1987
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C.,
Agents for the Applicant.