U.S. patent number 3,921,815 [Application Number 05/466,628] was granted by the patent office on 1975-11-25 for crane with a suspended rotatable counterbalance.
This patent grant is currently assigned to American Hoist & Derrick Company. Invention is credited to Archer W. Brown, deceased, Talford S. DeCuir.
United States Patent |
3,921,815 |
Brown, deceased , et
al. |
November 25, 1975 |
Crane with a suspended rotatable counterbalance
Abstract
A machinery deck of a counterbalancing crane is rotatably
mounted on a vertical axis on an upstanding pedestal in an offshore
location. An upwardly directed boom and an upwardly directed mast
are pivotally mounted with respect to a forward portion of this
deck for movement in a vertical plane passing through the axis of
rotation of the deck with respect to the pedestal. A counterweight
tank filled with sea water is pinned to the underside of a rearward
portion of the deck intermediate the outermost end of the rear
portion and the vertical axis of deck rotation. Counterweight
support wheels are rotatably mounted on vertical axes with respect
to a bottom portion of the counterweight; and a cylindrical
counterweight support collar is supported on the pedestal in
concentric relation to the axis of deck rotation and in position to
receive counterweight wheels. A suspension between an upper part of
the mast and an upper part of the boom and a suspension between the
counterweight and an upper part of the mast permits the
counterweight to act in a counterbalancing mode with respect to a
load suspended from a load line supported from the point of the
boom. A bearing platform is provided by the counterweight to be in
underlying relation to the outermost rear end portion of the
machinery deck so that as the entire counterbalancing effect of the
counterweight has been utilized and a counterweight tends to lift
its wheels away from the counterweight support collar, the upward
force on it is transmitted through this bearing platform to the
outermost rear end portion of the machinery deck.
Inventors: |
Brown, deceased; Archer W.
(late of Mendota Heights, MN), DeCuir; Talford S. (Houston,
TX) |
Assignee: |
American Hoist & Derrick
Company (St. Paul, MN)
|
Family
ID: |
23852507 |
Appl.
No.: |
05/466,628 |
Filed: |
May 3, 1974 |
Current U.S.
Class: |
212/195 |
Current CPC
Class: |
B66C
23/74 (20130101); E21B 15/02 (20130101); B66C
23/52 (20130101) |
Current International
Class: |
E21B
15/02 (20060101); B66C 23/74 (20060101); B66C
23/00 (20060101); B66C 23/52 (20060101); E21B
15/00 (20060101); B66C 013/16 (); B66C
023/72 () |
Field of
Search: |
;212/3,47-49 ;9/34
;114/5,44,121 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
815,501 |
|
Apr 1937 |
|
FR |
|
1,157,362 |
|
Nov 1963 |
|
DT |
|
859,092 |
|
Jan 1961 |
|
UK |
|
1,103,173 |
|
Feb 1968 |
|
UK |
|
140,554 |
|
Apr 1960 |
|
SU |
|
Primary Examiner: Spar; Robert J.
Assistant Examiner: Johnson; R. B.
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. In a crane having a first support, a machinery deck rotatably
mounted on a generally vertical axis with respect to said first
support, an upstanding mast and an upstanding boom both pivotally
mounted on a forward portion of the machinery deck for movement in
a vertical plane passing through the axis of rotation of the
machinery deck with respect to the support, a first suspension,
means mounting said first suspension between an upper portion of
said mast and an upper portion of said boom, a load line extending
over the point of said boom, means for rotating said deck, means
for powering the load line, and a load handling device supported by
the load line hanging from the point of the boom; the improvement
including:
A. a counterweight;
B. means for pivotally supporting said counterweight at a rearward
portion of the machinery deck for free swinging movement downwardly
with respect to that deck;
C. counterweight support wheels mounted with respect to the
counterweight to rotate on axes lying in planes containing the axis
of rotation of the deck;
D. a counterweight load bearing entity fixedly positioned with
respect to said first support and providing a counterweight load
bearing surface in position to receive said counterweight support
wheels;
E. means including said counterweight support means to cause said
counterweight to rotate with said deck in a horizontal plane;
F. a second suspension between said counterweight and an upper
portion of said mast; and
G. said counterweight being provided with a bearing platform in
position to come into bearing relationship to said rearward portion
of said deck when said counterweight is lifted by said second
suspension means from load transmitting relationship with said
counterweight load bearing entity.
2. The crane structure of claim 1 wherein the support is an
upstanding pedestal, wherein the counterweight load bearing entity
includes a cylindrical counterweight support collar fixedly mounted
with respect to the pedestal to be concentric with the axis of
rotation of the machinery deck with respect to the pedestal, and
wherein the counterweight support wheels are rotatably mounted on
axes parallel to the axis of said deck rotation.
3. The crane of claim 2 wherein said bearing platform is
constituted as an integral portion of said counterweight and is
situated in vertically underlying relationship with respect to an
outermost rearward end portion of the machinery deck.
4. The crane of claim 3 and shims between the bearing platform of
the counterweight and said outermost rearward end portion of the
machinery deck, said shims lying in intimate bearing, contacting,
force transmitting relationship with respect to both said bearing
platform and said outermost rearward end portion of said deck to
insure that every attempted upward movement of said counterweight
with respect to said deck will be transferred immediately and
completely to the rearward portion of said deck.
5. The crane of claim 3, wherein said counterweight is pivoted to
said rearward portion of said machinery deck at a point
intermediate the outermost rearward end portion of said deck and
said vertical axis of deck rotation.
6. The crane of claim 5, wherein said point of pivotal support of
said counterweight with respect to a rearward portion of said deck
is situated at a substantial distance from the outermost rearward
end portion of said deck.
7. The combination as specified in claim 6 wherein said means for
pivotal support of said counterweight at a rearward portion of said
deck includes upper and lower struts each pinned, respectively, to
upper and lower portions of the counterweight and each extending to
and encompassing the axis of said point of pivotal support of said
counterweight with respect said rearward portion of said deck.
8. The crane of claim 7 wherein said counterweight support wheels
include at least two sets of pairs of wheels, each set being
rotatably mounted about spaced apart vertical axes at opposite ends
of wheel beams, intermediate portions of such wheel beams being
pivotally mounted with respect to spaced apart lower portions of
said counterweight.
9. The crane of claim 8 wherein said pedestal is positioned in
adjacent surrounded relationship to a body of water, and wherein
said counterweight includes a hollow counterweight tank and water
drawn from said body of water filling said tank.
10. The crane of claim 9 wherein said pedestal is mounted fixedly
with respect to the earth floor underlying said body of water.
11. The crane of claim 9 wherein said pedestal is fixedly mounted
with respect to a vessel supported by said body of water.
12. In a crane having an upstanding pedestal, a machinery deck
rotatably mounted on a generally vertical axes with respect to said
upstanding pedestal, an upstanding mast and an upstanding boom both
pivotally mounted on a forward portion of the machinery deck for
movement in a vertical plane passing through the axis of rotation
of the machinery deck with respect to the pedestal, a first
suspension between an upper portion of said mast and an upper
portion of said boom, a load line extending over the point of said
boom, means for rotating said deck, means for powering the load
line, and a load handling device supported by the load line hanging
from the point of the boom; the improvement including:
A. a counterweight;
B. means for pivotally supporting said counterweight at a rearward
portion of the machinery deck at point intermediate the outermost
rearward end portion of said deck and said vertical axis of deck
rotation and at a substantial distance from the outermost rearward
end portion of said deck, said means supporting said counterweight
for free swinging movement downwardly with respect to said deck and
said means including upper and lower struts each pinned,
respectively, to upper and lower portions of the counterweight and
each extending to and encompassing the axis of said point of
pivotal support of said counterweight with respect to said rearward
portion of said deck;
C. at least one counterweight support wheel mounted with respect to
a lower portion of the counterweight to rotate on an axis lying in
a vertical plane;
D. a cylindrical counterweight support collar fixedly mounted with
respect to the pedestal to be concentric with the axis of rotation
of the machinery deck and providing a counterweight load bearing
surface in position to receive said counterweight support
wheel;
E. means including said counterweight support means to cause the
counterweight to rotate with said deck; and
F. a second suspension between said counterweight and an upper
portion of said mast.
13. The crane of claim 12 wherein there are at least two wheel
beams and at least two sets of pairs of wheels, each set being
rotatably mounted about spaced apart vertical axes at opposite ends
of said wheel beams, intermediate portions of such wheel beams
being pivotally mounted with respect to spaced apart lower portions
of said counterweight.
14. The crane of claim 13 wherein said pedestal is positioned in
adjacent surrounding relationship to a body of water, and wherein
said counterweight includes a hollow counterweight tank and water
drawn from said body of water filling said tank.
15. The crane of claim 14 wherein said pedestal is fixedly mounted
with respect to the earth floor underlying said body of water.
16. The crane of claim 14 wherein said pedestal is fixedly mounted
with respect to a vessel supported by said body of water.
Description
BACKGROUND OF THE INVENTION
This invention has relation to counterbalancing cranes of the
pedestal type. Such cranes are used for handling cargo from
seagoing vessels to floating platforms or to fixed platforms
mounted on the sea bottom. They find particular usefulness in
offshore oil drilling operations, for example.
It is now well known to support a counterweight on a horizontal
supporting surface behind a rearward portion of a rotatable
machinery deck in such a manner as to have the counterbalancing
effect of the counterweight when needed in handling heavy loads.
See application of Archer W. Brown et al., filed Dec. 11, 1972, for
CRANE COUNTERBALANCING TRAILER ASSEMBLY, now U.S. 3,842,984; No.
3,842,984 a continuation-in-part of application Ser. No. 102,500,
filed Dec. 29, 1970; which was a continuation of Application Ser.
No. 767,670, originally filed Oct. 15, 1968, now abandoned. See
also U.S. Pat. No. 3,485,383.
In the Archer Brown patent, downward stress on the machinery deck
by the counterweight is completely avoided by attaching the
counterweight to the machinery deck to rotate with the deck, but by
supporting it on wheels running on a relatively flat horizontal
surface on which the crane carbody is supported. However, in order
to utilize the weight of the rearward portion of the machinery deck
as additional counterweight at the point when the counterweight is
no longer relying on the ground for its support, it is necessary to
critically control the relationship between the mast to
counterweight suspension and the mast to machinery deck suspension.
Only in this manner does the outermost rearward end of the
machinery deck become available to counterbalance the load on the
boom as the counterweight is lifted from the supporting
surface.
Neither the horizontal supporting surface as shown in the Archer
Brown patent nor the ring as shown in U.S. Pat. No. 3,485,383 are
available for use with pedestal mounted cranes of the general type
as disclosed in U.S. Pat. No. 2,703,180, for example. This is
because no economically feasible, effective means of providing a
horizontal support surface for the counterweight is available
without introducing destructive or at least unsafe torque forces in
the pedestal.
However, it is desirable in such pedestal mounted cranes to provide
counterweight support for handling very heavy loads while not
unduly stressing the machinery deck and the pivotal mounting
connections between the machinery deck and the pedestal when such
heavy loads are not being handled.
SUMMARY OF THE INVENTION
A machinery deck of a counterbalancing crane is rotatably mounted
with respect to an upstanding pedestal or other support. This
support can be a pedestal fixed to the sea floor or to a floating
barge in an offshore location; or can be a carbody or the like
temporarily or permanently fixed to the ground. An upwardly
directed boom and an upwardly directed mast are pivotally mounted
with respect to a forward portion of this machinery deck for
movement in a vertical plane passing through the axis of rotation
of the deck with respect to the support. A counterweight is
pivotally mounted with respect to the deck on a horizontal axis
perpendicular to this vertical plane, in such a manner that
rotation of the deck on its vertical axis will cause rotation of
the counterweight about the same vertical axis. A first suspension
means connects an upper portion of the mast with an upper portion
of the boom, a second suspension means connects the counterweight
with an upper portion of the mast, a load line extends over the
point of the boom to connect to a load handling device, means is
provided for rotating the deck, and means is provided for spooling
the load line.
A counterweight load bearing entity is provided with a
counterweight load bearing surface, and counterweight support means
are provided for supporting a portion of the counterweight in load
bearing relationship to such load bearing surface when the load
line, the mast, the boom, the first suspension means and the second
suspension means are not supporting a maximum load. Said
counterweight support means is such as to permit the counterweight
to rotate horizontally with the deck and with respect to said
pedestal or other support. Cooperating bearing means are provided
between the counterweight and a rearward end portion of the
machinery deck for transmitting upward forces on the counterweight
to said rear end portion of said deck when the load on said load
line causes the second suspension means to lift the weight of the
counterweight from the counterweight supporting entity.
In the form of the invention as shown, the counterweight load
bearing entity is constituted as a cylindrical, horizontally
disposed, counterweight support collar mounted on a pedestal to be
concentric with the axis of machinery deck rotation; and the
counterweight support means includes wheels rotatably mounted on
vertical axes with respect to a lower portion of the counterweight.
The cooperating bearing means includes a bearing platform
constituted as an integral part of the counterweight in underlying
vertically aligned relationship to an integral outermost rearward
end portion of the machinery deck. Also as disclosed herein, shims
are provided between this outermost portion of the deck and the
counterweight bearing platform so that any upward movement of the
counterweight will be immediately transmitted to the rearward end
portion of the deck. The point of pivotal mounting of the
counterweight with respect to the deck, in the form of the
invention as shown, is located between the vertical axis of
rotation of the deck with respect to the pedestal and the outermost
rearward end portion of the deck.
As shown, the counterweight is constituted as a hollow tank which
can be filled with sea water, for example.
In the drawings:
FIG. 1 is a side elevational view of an offshore counterbalancing
crane of the invention showing a pedestal mounted to this sea
floor;
FIG. 2 is an enlarged horizontal sectional view taken generally on
the line 2--2 in FIG. 1; and
FIG. 3 is a fragmentary vertical sectional view taken generally on
the line 3--3 in FIG. 2 and at a somewhat reduced scale but showing
the pedestal mounted on a floating barge.
DESCRIPTION OF PREFERRED EMBODIMENT
An offshore counterbalancing crane 10 includes a cylindrical
pedestal 12 permanently fixedly mounted in the sea floor 14 on a
floating barge 15, in any usual or preferred manner, and a
machinery deck 16 rotatably mounted on the pedestal 12.
A boom 18 is pivotally mounted to a forward portion 20 of the
machinery deck 16, as is a mast 22.
A counterweight 24 includes a counterweight tank 26 filled, for
example, with sea water 28. This counterweight is pivotally mounted
or pinned as at 30 to a rearward portion 32 of the machinery deck
16 through the instrumentality of a downwardly extending strut 34
and a generally horizontally extending strut 36. These struts are
pinned to the counterweight at 38 and 40 respectively.
A first linkage or suspension 44 is connected between the tip of
the mast 22 and the point of the boom 18. As shown, this first
suspension is adjustable in length by operating appropriate
machinery 45 on the machinery deck 16, to lengthen and shorten the
distance between the sheaves 46, 46 due to lengthening and
shortening of first suspension control line 48. A second linkage or
suspension 42 is connected between an upper portion of the
counterweight tank 26 as at 43, and the top of the mast 22 as at
41. A load line, or load lines 50 pass over a sheave at the point
of the boom 18 and are connected to load handling devices such as
load hooks 52. Machinery 54 is provided, on the machinery deck as
shown, for controlling the length of the load lines. Machinery 45
and 54 can be of any usual or preferred construction and can be
located at any convenient place just so long as the control line 48
passes to the sheaves 46 and the load line 50 passes over the boom
point.
A shock absorbing boom stop 56 is pivotally mounted to the
machinery deck and to the boom 18 to prevent movement of the boom
to a position where it would have a tendency to fall toward the
rearward portion of the machinery deck.
The rotatable mounting of the machinery deck 16 to the pedestal 12
can be accomplished, as best seen in FIG. 3, by providing a
combination bull gear and roller path 58 as the top cap of the
pedestal. A bull gear center pin 59 extends integrally upwardly
therefrom. A bull gear center pin bushing 60 fits over pin 59 and
is constituted as an integral part of machinery deck structure, as
are load roller and hook roller brackets 62, 62. Load rollers 64
are rotatably mounted on the brackets 62 to support the machinery
deck on a roller path flange 66 of the combination bull gear and
roller path 58. Hook rollers 68 are rotatably mounted on these
brackets 62, run on the bottom side of flange 66, and serve to
resist any upward forces exerted by the machinery deck on the
flange. Other equally suitable means of rotatably mounting the deck
to the pedestal could be employed without departing from the spirit
or scope of the invention.
A counterweight load bearing entity 70 includes, in the form of the
invention as shown, a cylindrical counterweight support collar 72
integrally supported on the cylindrical pedestal 12 in concentric
relationship to it and to the vertical axis of the bull gear and
roller path 58 as by horizontally outwardly extending plates or
flanges 74, 74.
Counterweight support means 76 includes counterweight support
wheels 78 each rotatably mounted on a vertically disposed axle 80
which, in turn, are supported in horizontally disposed wheel beams
82. These wheel beams are pivotally mounted as at 83 to
counterweight wheel brackets 84 which are integral with and extend
outwardly from a lower portion of counterweight tank 26.
Counterweight tank 26 is also provided with a bearing platform 86
which is in vertical alignment immediately under an outermost
rearward end deck bracket 88 integral with the outermost end of the
rearward portion 32 of machinery deck 16. With the parts positioned
as seen in FIGS. 1 and 3, one or more metallic shims 90 are
situated between and in contact with the platform 86 and the
bracket 88 to insure that any upward movement whatever of
counterweight tank 26, and consequently bearing platform 86, is
directly transmitted to the outermost end of the rearward portion
32 of the machinery deck 16 through the bracket 88.
OPERATION
With the parts of the counterbalancing crane positioned as seen in
FIG. 1, no working load is present on the load hooks 52, so the
upward force exerted by second suspension 42 on the counterweight
24 will be at a minimum. In this configuration, the counterweight
24 is supported on the machinery deck entirely by struts 34 and 36
and by the pivotal mounting at 30 of those struts to the underside
of the rearward portion of the machinery deck 16. Being free to
pivot about the pin 30, and with no other connection to the
machinery deck 16, a considerable force is exerted by a lower
portion of the counterweight and through the counterweight support
wheels 78 onto the cylindrical counterweight support collar 72.
This causes an equal and opposite shear force to be exerted by the
bull gear center pin bushing 60 on the bull gear center pin 59,
fixedly positioned, as it is, with respect to the pedestal 12, in
the form of the invention as shown.
As is usual in structures of this kind, a drive pinion, downwardly
extending from the machinery deck 16 into the interior of the bull
gear 58, meshes with this bull gear. To rotate the machinery deck
with respect to the pedestal, power means are provided to turn the
pinion on its axis, thus to cause the machinery deck 16 to rotate
relative to the bull gear and roller path combination 58. Means for
rotating the machinery deck with respect to the pedestal are not
specifically shown, as this can be accomplished in any usual or
preferred manner, forming no part of the present invention.
As the machinery deck 16 is rotated relative to the combination
bull gear and roller path 58, and consequently, relative to the
pedestal 12, the struts 34 and 36 will cause the counterweight 24
to turn with the check. This will cause the wheels 78 to roll
around the outer periphery of the cylindrical counterweight support
collar 72. The downward component of the weight of the
counterweight will be carried by the machinery deck at the pin 30.
This pin 30 is spaced relatively close to the axis of rotation of
the deck, thus creating much less bending moment than would be the
case if it were supported at the outermost rear end portion of the
deck 16.
In the no load condition, the maximum vertical "dead weight" effect
of the counterweight acts at a lever arm length equal to the
horizontal distance between the pin 30 and the vertical axis of
rotation of the machinery deck 16. Since this is the maximum
rearward bending stress condition, and since it is present under
minimum or no load conditions only, the various elements of the
counterbalancing crane are easily designed to safely handle such
loading.
This no load condition is also the condition of maximum normal
stress of the counterweight 24 acting through the counterweight
support means 76 and onto the pedestal mounted cylindrical
counterweight support collar 72. Because the cylindrical wall of
collar 72 is vertical, there is no component of force transmitted
in the downward direction through the support collar 72 and onto
the pedestal 12. The only force here involved is that in direction
perpendicular to the axis of the support collar and lying in a
generally horizontal plane. Thus by providing sufficient rigidity
and stiffness in the pedestal and in the pedestal support collar
and in the radially outwardly extending plates 74, 74 which support
the collar on the pedestal to support a known maximum force, safe
and economical design is readily achieved.
In order to figure the necessary strength of the parts to support a
maximum load to be handled, after the no-load bending effects set
out above have been considered, the compressive loading caused by
the weight of the counterbalancing crane and the counterweight,
plus the weight of the maximum working load for which the crane is
being designed are taken into consideration.
When one of the load hooks 52 is engaged with a working load, and
machinery 54 is employed to reel in the load line 50 so that the
crane 10 can lift that load, the boom 18 is positioned or
maintained in its upright position through the first suspension 44
and by the connection of that first suspension to the tip of the
mast 22. The mast, first suspension, boom, the load hooks 52 and
the work load (not shown) are supported in place by the second
suspension 42, connected as it is between the top of the
counterweight 24 and tip of mast 22. As more and more weight is
exerted on the load lines 50, the upward forces existing in second
suspension 42 are increased. As this happens, the downward force
component on the pin 30 is lessened, and the horizontal force
component through the counterweight wheels 78 to the cylindrical
counterweight support collar 72 is likewise lessened.
As this loading continues, a point is reached where there is no
longer any force being exerted by the counterweight wheels 78 on
the outer cylindrical surface of the support collar 72. At this
point, the counterweight tends to pivot about the pin 30 so that
the wheels 78 tend to move clear of the collar 72. This movement is
resisted by the shims 90 and outermost rearward end deck bracket 88
at the outermost end of the rearward portion 32 of the machinery
deck 16. But the machinery deck itself is a flexible structure in
and of itself and is not rigid. Therefore, once the entire weight
of the counterweight is supported on second suspension 42,
additional counterbalancing effect is obtained by the flexing of
the rearward portion 32 of machinery deck 16, as the load on the
load lines 50 is increased. Additional load can be handled until
the designed limits of the total loading of the flexible deck and
of the weight of the counterweight is reached.
As pointed out above, when the load is first picked up, the upward
force exerted by the load, the boom, first suspension and the mast
on the second suspension 42 and consequently on the counterweight,
tend to lighten the loading of the rearward portion of the
machinery deck. The forward portion of that deck is, at the same
time, being downwardly loaded as the downward component of the
weight on the load line is transmitted at the points of pivotal
mounting of the mast and boom to the forward portion of the
machinery deck. Thus the maximum tendency of the machinery deck to
be "bent over backwards" is present in the no-load condition. This
loading of the machinery deck toward the rear approaches and
reaches a minimum as the load is picked up, and then passes to a
maximum tending to load the front end of the machinery deck as the
entire weight of the counterweight is picked up by the mast acting
through the second suspension 42, and as the rearward portion of
the deck is flexed as the counterweight continues to be pulled
upwardly.
As will be seen from the foregoing description, the horizontal
force components due to the weight of the counterweight in the
unloaded condition are carried by the counterweight load bearing
entity 70. As the entire weight of the counterweight is supported
in counterbalancing configuration, and the bearing platform on the
counterweight cooperating with the outermost rear end of the deck
prevents further upward movement of the counterweight, the
horizontal force components disappear.
Under no load conditions, the downward effect of the counterweight
on the rotatable machinery deck is minimized because there is no
connection between the counterweight and the outermost rear end of
the deck until such time as the entire weight of the counterweight
has come into counterbalancing configuration.
At this point, the counterweight is connected under the outermost
rear end portion of the machinery deck, and the whole weight of
that portion of the machinery deck and the flexible strength of the
rearward portion of the deck is added to the counterbalancing
effect of the counterbalance. This is so whether the counterweight
load bearing entity is a cylindrical collar mounted in concentric
relation to the axis of rotation of the platform on a pedestal, as
shown herein, or whether the counterweight load bearing entity is a
horizontally disposed ring or track such as disclosed in U.S. Pat.
No. 3,485,383.
* * * * *