provements in Cranes.
Year: 1898

page_text: Date of Application, 7th June, 1898
Complete Specification Left, 2nd Mar, 1899-Accepted, 8th Apr., 1899
PROVISIONAL SPECIFICATION
Improvements in Cranes.
I, ALFXANDER GRAFTON, of Vulcan Works, Bedford, in the County of Bedford-
shine, Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to a device or mecanism for indicating the radius of the
Jib of a rotating crane and is applicable to all cranes having a radiating derricking
or jib adjusting motion by means of which vertical angular motion is imparted
to the jib and the point of suspension of the load is brought nearer to or farther
from the centre pivot of the crane, the jib being pivotted at its foot and suspended
by ropes or chains wound on or off a drum or barrel in the usual manner is thus
aised or lowered and at the same time the radius of the jib is reduced or increased,
to this barrel I connect by means of suitable positive gearing a dial which indicates
by a pointer the distance corresponding to the actual radius for the time being
of the hook and (or) the corresponding load it will carry
Dated thath day of Tu 1900
I, ALEXANDER GRAFTON, of Vulcan Works, Bedford, in the County of Bedford-
shire, Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
n and by the following statement .-
This invention relates to cranes (especially portable cranes) which are provided
with a so-called derick motion for varying the radius of the crane by varying
the vertical angle of the jib, and the invention has for object to provide means
of automatically indicating to the person in charge of the crane the radius of the
crane for the time being and the maximum load which may be safely carried at
that radius having regard to the stability of the crane and the strength of the
various parts, the indicator serving also to denote the radius which should be
adopted in order that a given maximum load may be safely carried.
The invention consists in the combination with the jib-adjusting gear, and in
particular with the barrel whereon the jib-adjusting and supporting chains are
wound or the pulley around which they pass, as the case may be, of a dial and
index whereof the one is carried by a rotatable axis in gear with the said chain
barrel or pulley so as to be revolved thereby the gearing being so proportioned
that the said rotary part will make less than one complete revolution for the
[Price 8d 1

page_text: maximum number of revolutions of the barrel or pulley required for effecting the
adjustment of the jib between the extreme limits employed in practice. This
rotary part may be either the dial on the index, the dial being in either case
marked with a circuar scale or scales denoting the radius of the crane at each
of various different adjustments of the jib and the maximum load corresponding
to each such radius so that both indications may be read off at once by reference
to the index
In the case of a portable crane provided with a double set of wheels adapted to
run either on rails of ordinary, or of extra wide, gauge the dial may have two
scales differing in the ratio of the load to the radius of the crane, in correspondence
with the difference of stability of the crane when on a broad or a narrow wheel
base, the scales being either concentric upon the same face of the dial or being
praferably on opposite faces of the diab which would in that case be reversible
so that only one scale is visible at a time
The invention is illustrated in the accompanying diawings forming part of this
Specification wherein Figure 1 is a diagrammatic view of a clane provided with
the indicator Figures 2 and 3 are face views of the indicator, shewing opposite
sides of the dial The same letters of reference denote like parts in all the figures.
In the example illustrated the dial iotates and the index is stationary. The
dial D has engraved or otherwise marked on it, al circular scale of,
say, 8 radial divisions, more or less, corresponding to, say, every
2 feet variation of radius of the crane from, for example, 18 feet to 32 feet The
dial is mounted to rotate upon a centre stud S fixed to the main side frame A of
the crane and in such position as to be readily visible to the driver whether he
be standing on the foot plate or on the ground The periphery of the dial is
toothed and in gear, duectly or through intermediate gear wheels, with a pinion P
fast on the outer end of the journal of the derrick barrel B whereon the chains C
for adjusting and supporting the jib J are wound, the ratio of the gearing and
the divisions of the scale being in such proportion to the jib-adjusting gear that
the readings on the dial with reference to a stationary index I mounted on the
side frame A of the crane, will correspond for all adjustments of the jib, with the
horizontal distances from the crane centie to the load-carrying hook The dial
shewn 18 reversible and 19 removably mounted on its centre stud S on which it 18
retained by a nut so that it may be readily reversed, as shewn in Figures 2 and 3.
In order that the division of the scale should comespond accurately with the
adjustment of the jib for a given number of revolutions of the barrel, it is desirable
that the division should be set off in the first instance by actual reference to a
crane so that the necessary allowance may be made by the contraction of the
scale, for the varying angular relation of the jib to its supporting chains in its
different positions of adjustment
It will be obvious that the dial, instead of being itself toothed, may be a plain-
edged disc affixed to an underlying toothed wheel permanently in gear with the
pinion, the rotat v connection of the dial with the toothed wheel being, for instance
by a steady pin on the latter entering a hole in the former so that when the dial
18 reversed its correct position with regard to the index and to the then position
of the jib will be necessarily ensured
In order to compensate for stretching of the jib-supporting chains the indicator
radius reading may be corrected from time to time by reference to actual
measurement of the crane radius, by shifting the intergearing of the teeth of the
pinion with that of the dial or the dial-carrying wheel, to the extent of one tooth
or more as required
The index I is preferably at one side of the dial so that the radius and load
readings which come opposite thereto may be read off in one horizontal line but
it will be obvious that the index might be fixed in the vertical or any other
radial position
If the index be the rotating part, it would be fixed 'on, and rotate with, the
hub of a gear wheel such as D, which would not in that case be marked as a dial,

page_text: the index moving in that case over a fixed dial bearing in concentric circles, the
two scales of radu and loads corresponding to the broad and narrow wheel base
Where, as in the case of some cranes, the barrel on which the jib-adjusting
chain C is wound 18 situated low down near or beneath the foot plate, the chain
being led over a pulley situated in the position here shewn as occupied by the
barrel B, the pinion P instead of being fast with the barrel woull be fast on the
shaft of said pulley and turn therewith so that the indicator would be operated
by the passage of the chain over the said pulley in the same way as by the
winding of the chain on the barrel, the construction and operation of the indi-
cator being, in other respects, the same as above described."
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed I declare that what I
claim 18:-
1 In a crane provided with a derricking or jib-adjusting gear the combination
with the said jib-adjusting gear, of an indicator consisting of a rotatable part
geared with the jib-adjusting chain through the medium of its barrel or pulley
so as to be rotated concurrently with the adjustment of the jib and of a stationary
part, the one said part being divided to indicate with reference to the other said
part the radius of the crane for the time being and the maximum load which
may be carried at each radius substantially as specified.
2 In a portable crane provided with a derricking or jib-adjusting gear the
combination with the said jib adjusting gear, of an indicator consistang of a dial
rotatable in reference to a stationary pointer, the dial being geared with the jib-
adjusting chain barrel or pulley and being divided to indicate for all positions
of the jib adjustment the radius of the crane for the time being and the maximum
load which may be carried at each radius substantially as specified.
3. In a portable crane provided with a derricking or jib-adjusting gear and
with two sets of running wheels to adapt it to railways of two different gauges
the combination with the said Jib-adjusting gear, of an indicator consisting of a
reversible dial mounted to rotate in reference to a stationary index, the dial being
geared with the jib-adjusting chain barrel or pulley and being divided on both
its faces with scales of radii and loads coresponding to various positions of jib-
adjustment, the load indications of the scales differing for the same radius in
proportion to the difference of stability of the crane when standing on the one
or other gauge of railway as described
1000
A. M & WM CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.