Note: Descriptions are shown in the official language in which they were submitted.
1081168
This invention relates to a liftinq 2evice employed to
elevate an object, transfer it to a different location, and to
lower and release it.
The concept of balancing cranes has been recognized in
the prior art as a desirable objective, but the coordinated
movements of counterweights on gantries or booms to accomplish
this in an acceptable meanner has not been heretofore proposed.
See, for example, United States Patents Nos. 734,974 to
Shoosmith and 3,642,148 to Durand.
This invention provides a constant balance crane
particularly suited to those environments of use wherein a load
must be lifted and transported the full length of the crane
gantry before release. Examples of situations wherein this
occurs would include bulk material loading and unloading, factory
uses, dockside applications, and the like. The present
arrangement is such that the counterweight means hereof travels
on a boom or gantry component independent of the lift means,
thereby permitting a bypass or crossover relation between the
conveyed load and the counterweight.
In some embodiments of the invention, a plurality of
counterweights, each movable in unison on independent gantry
members, is provided. This lends additional stability and
permits positioning of the weight-bearing member between the
counterweights.
In other embodiments, unique bypass rail systems are
provided, allowing precise counterweight adjustment.
A hydLaulic drive hereof includes tilt sensing means
controlling operation of counterweight actuation, whereby
constant balance is ~aintained during load transfer.
In the drawings:
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108116~
Figure 1 is a side elevational view of a constant
balance crane constructed and assembled in accordance with the
teachings of this invention;
Figure 2 is a top plan view thereof;
Figure 3 is a schematic rendition of the hydraulic
system hereof;
Figure 4 is a schematic diagram of the tilt sensing
and control valve means hereof;
Figure 5 is an enlarged cross-sectional view showing
details through a column base of the crane tower;
Figure 6 is a perspective view of the crane, certain
components being removed, to illustrate the counterweight
mounting;
Figure 7 is a view similar to Figure 6, but partially
broken away, and with other components removed to show the
mounting of the lift trolley;
Figure 8 is an enlarged sectional view through the
gantry;
Figure 9 is a side elevational view of the lift trolley
assembly in place on its gantry member;
Figure 10 is a view similar to Figure 8, partially
broken away, and showing a modification;
Figure 11 is a side elevational view showing another
modification;
Figure 12 is an enlarged vertical cross section through
the gantry of the Figure 11 embodiment; and
Figure 13 is a view similar to Figure 12 showing anoth~r
modification.
In Figure 1, a constant balance crane according to this
invention is identified generally by reference character 20. The
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crane mounting is of course variable according to employment, but
illustratively has a base 22. ~ounted in four hubs 24 (in a
manner described below~ on the base 20 are four posts or standards
26 which project vertically. mhese posts are joine~ together by
means of beams 28 and 30 at their upper ends, and by diagonal
braces 32. As shown in Figure 6 and 7, top cross brace members
34, in pairs, also connect the same. The columns are also
connected by cross beams 36, and the columns, beams, girders and
base provide a tower assembly for the crane.
Securely mounted in horizontal fashion below the cross
beam 36 is a plurality of gantry members, here including a central
gantry 38 and outer gantries 40 (Figures 2, 7 and 8). Each
comprises a heavy I-beam having a vertical central web 42, with
outer lower ledges 44, 46 and upper ledge elements 48, 50 on
either side thereof. The beams are fixedly secured to the cross
beams 36 at their tops, and are also braced by suitable top
plates 52 and interconnecting plates 54, with vertical tabs 56.
The respective gantry members have outer ends 58 and 60.
~ lounted for horizontal movement on the central gantry
member 38 is a lift trolley assembly 62. The lift trolley
includes a main trolley plate 64 having fore and aft ends 66, 68
and having depending front and rear brackets 70, 72 at said ends.
Projecting from the sides of the plates are upward extensions 74
and 76 reinforced by gusset plates 78. On the extensions are
inwardly extending stub axles 80 on which wheels 82 are rotatably
mounted. The wheels ride on the ledges 44 and 46 of the central
gantry member.
A cable drum 84 is positioned on a shaft 86 mounted in
~he brackets 70 and 72 (Figure 9j. A mount 88 secures a hydraulJc
cable motor 90, which rotates the drum to raise or lower a lift
1~1168
cable 92 with a hook 94 for the Ioad 96 to be lifted.
Referring to Figures 7 and 9, it will be observed that
a transport cable 98 is connected to the bracket 70 on an eye 100
at one end, and is also connected on an eye 102 at another end
thereof. The cable is trained about pulley wheels 104, 106
mounted in pairs at the ends 58 and 60 of the gantry, and about
an idler pulley 108 on a tower top cross beam 34. A trolley
travel motor 110 has a drum 112 for driving the transport cable,
and the motor is mounted on the opposite tower cross beam. The
motor is of the reversible direction type, whereby the lift
trolley may be propelled in either direction on the gantry by
appropriate winding of the cable.
On the outer gantry members 40, which may be of any
desired number, are movably mounted counterweight trolley
assemblies 114. These are identical, and a description of one
will cover all, the assemblies each having a horizontal body 116
with ends 118, and having a plurality of upstanding, spaced legs
120, 122 at its sides on opposite sides of the web of the
associated I-beam. Stub axles 124, 126 project toward the web 40
from the legs, and carry rotatable wheels 128. The wheels 128
ride on the ledges 44 and 46. Side plates 130, 132 depend from
the body 116, and are spanned by a cross shaft 134. A heavy bar
136 is suspended on the cross shaft, and has a weight 138 thereon.
Figure 6 illustrates the means for movement of the
counterweight trolleys 114. As there shown, a counterweight
control cable 140 is secured to eyes 142 on both of the ends of
the body portion 116. The cable is trained about idler pulley
wheels 144, 146 on the gantry ends, and about an idler pulley 148
on one of the cross beams of the tower. On the opposite cross
beam 34 is a hydraulic motor 150 with a shaft 152 having winding
1~81~8
drums 154. As the motor is rotated in selected direction, the
shaft turns, causing take up/pay out of the cable and moving the
counterweights in unison on the gantries.
In Figure 10, a modification is shown wherein the
counterweight trolley 114a has a separate hydraulic motor 200
connected to a shaft 202 extending between the plates 130a and
132a, respectively, to raise and lower the center of gravity of
the crane. The shaft carries a reel 204 with a cable 206 which
permits raising and lowering of the weight 138a.
As indicated above, Figure 5 shows a base 22 of the
crane having a series of hubs 24 for the posts 26. On the lower
end of each post, within the hub, is a flange 300 with a rod 302.
Formed in the base 22 is a chamber 304 with an embedded housing
306a into which the rod 302 extends. The rod carries a plunger
308 on its lower extremity, and a hydraulic line 324 extends
from the lower end of the housing 306a.
Figure 4 shows two of the tower post mounts in
diagrammatic fashion. They are of side to side relationship,
and in many instances, four such arrangements are employed. This
description is limited to two post arrangements to avoid obscuring
the purpose and structure of the unit. In Figure 4, it will be
observed that a line 324 or 326 extends from each of the side-by-
side housings 306a and 306b, each of which has a plunger and a
hydraulic line. These in turn are connected to a double-acting
hydraulic cylinder 312 having an internal plunger 314. It will be
recognized that a supply of hydraulic fluid is mai~tained within
the system. As a load is placed on one of the posts 26, it
creates a downward moment on the rod 302 associated therewith, and
correspondingly reduces the pressure on the components of the
other post of the system. This in turn forces hydraulic fluid
68
from the chamber of the load bearing post and through the line 324
or 326 causing appropriate movement of the plunger 314 within the
cylinder 312. This movement is transmitted through a shaft 316
having a hydraulic pinch valve 318 with two valve members 320 and
322. The valve 318 is positioned between a pair of hydraulic
lines 330 and 332. The pinch valve members 320 and 322 are
adapted to restrict the flow of hydraulic fluid through either the
line 332 or the line 330 as shown.
Referring to Figure 3, the details of the sensor
control of Figure 4 are there omitted, but it will be observed
that the lines 324 and 326 are shown. These lines lead to a
proportional control valve as shown only in block form and
identified by reference numeral 328. From the control valve 328
extend lines 330 and 332 which in turn extend to the motor 150
which propels the counterweight trolleys. Fluid from the motor
is returned to a reservoir 352 by a return line 333. Means for
supplying the hydraulic force to the proportional valve includes
a line 334 to a prime mover 340. The prime mover 340 actuates
the entire hydraulic system hereof.
With continued reference to Figure 3, reference numeral
342 identifies a manual control for the lift mechanism. The
manual control has output lines 344 and 346 extending to the motor
90 of the lift mechanism. The manual control has an input line
348 extending to a pump 350 connected to a gear box 352 of the
gearbox bank. Fluid from the motor is returned to the reservoir
352 by a hydraulic return line 354 from the motor.
A secon2 manual control valve ~56 is provided for
movement of the lift trolley. It is supplied by a line 358
extending to a pump 360 and gearbox 362 of the bank of gearbox
controis. Extending from the second manual control are lines
1~81168
364, 366 which control the operation of the trolley motor 110.
Fluid from the motor 110 is returned to the reservoir 352 through
a return line 368.
From the foregoing, it will be clear that as the
operator, through actuation of the manual control 356, moves the
lift trolley across the gantry, the tilt moment applied to the
gantry by the load is sensed by the posts and this in turn is
transmitted via the hydraulic lines 324 and 326 and pinch valve
318 to activate the proportional control 328 and propel the
counterweight trolleys in the selected direction.
The phantom lines in Figure 3 illustrate a further
manual control 370 which is used with the modification previously
discussed and shown in Figure 10 of the drawings. This is simply
another manual control, and it will be observed that it includes
lines 372 and 374 extending to the motor 200. A return line 376
returns fluid to the reservoir 352 where this is used, and a
supply line 378 extends back to a pump 380 with a gearbox 382
embodied in the gearbox bank. It will also be noted generally
that the supply for the fluid is transmitted through a line 384
from a reservoir through a distributor valve 386 which, through
appropriate connections, supplies each of the hydraulic pumps.
In Figure 11, a tower 20b has top beams 30b and diagonal
braces 32b. Horizontally mounted below the braces on the tower
by means extending from the column 26b is a gantry 400.
Referring to Figure 12, it will be observed that the gantry 400
includes parallel I-beams 402 and 404.
The beams 402 and 404 each have a central rib 406 and
top and bottom flanges 408 and 410. At spaced locations, the
beams are connected together by cross braces 412.
Fixedly secured on the top flanges 408 are
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1~811~i8
longitudinally extending rail members 414, 416. A counterweight
truck or trolley 418 has a bed 420 with depending bearings 422,
and axles 424 extend through the bearings. Railroad-type wheels
426 having inside flanges 428 are provided on the axles and
permit the counterweight truck to ride on the rails. A box 430
on the bed is used as a container for counterweight material. The
counterweight truc~ is movable on the gantry through propulsion
means of the type described in connection with the first forms
of the invention.
A lift trolley 432 for this form of the invention
comprises a trolley plate 434 having depending brackets 436
supporting a winch 438 and motor 440 for a lift cable 442. From
the top of the plate 434 extend pairs of uprights 444, 446, braced
by gusset plates 448. These carry stub axles 450 on which roller
wheels 452 are rotatably mounted. These wheels ride on the
ledges provided by the bottom flanges 410. Propulsion of the
lift trolley is also described above in connection with the other
forms of the invention.
Thus, in this form of the invention, the counterweight
trolley bypasses the load trolley in overhead fashion. Operation
is otherwise as described above.
Figure 13 shows yet another embodiment wherein the
gantry 500 is composed of three I-beams 502, 504, and 506. The
rails 508 for the counterweight trolley 510 are fixedly secured
on the outer I-beams 502 and 506, while the load trolley 512 is
mounted on the central I-beam 504.
