US3597865A

US3597865A - Attitude adjuster for dragline bucket

Info

Publication number: US3597865A
Application number: US816303A
Authority: US
Inventors: Henry Rumfelt
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-04-15
Filing date: 1969-04-15
Publication date: 1971-08-10
Anticipated expiration: 1988-08-10

Abstract

A device for insertion between the hoist rope and hoist chain of a dragline bucket which provides a movable support for the dump sheave. The device includes a spring suspension of the hoist chain with respect to the hoist rope whereby lifting the bucket with a load therein will act to compress the spring to move the dump sheave with respect to the hoist trunnions, thereby increasing the moment arm of the offcenter weight on the dump rope to reduce the amount of force necessary to lift the bucket while maintaining proper bucket attitude to prevent premature dumping.

Description

United States Patent [72] Inventor Henry Rumielt 300 N. Grove Ave., Oak Park, 111. 60302 [21] Appl. No. 816,303 [22] Filed Apr. 15, 1969 [45] Patented Aug. 10, 1971 [54] ATTITUDE ADJUSTER FOR DRAGLINE BUCKET 3 Claims, 5 Drawing Figs.

[52] 1.1.8. Cl 37/135, 267/71 [51] Int. Cl 110213/44 [50] Field 37/115- [56] Reierences Cited UNITED STATES PATENTS 2,814,890 12/1970 Mutti 37/135 2.482,829 9/1949 Adams 37/135 Primary Examiner-Robert E. Pulfrey Assistant Examiner-.1 Reed Fisher Anorney-Hill, Sherman, Meroni. Gross & Simpson ABSTRACT: A device for insertionbetween the hoist rope and hoist chain of a dragline bucket which provides a movable support for the dump sheave. The device includes a spring suspension of the hoist chain with respect to the hoist rope whereby lifting the bucket with a load therein will act to compress the spring to move the dump sheave with respect to the hoist trunnions, thereby increasing the moment arm of the offcenter weight on the dump rope to reduce the amount offorce necessary to lift the bucket whfle maintaining proper bucket attitude to prevent premature dumping.

2 Sheets-Sheet 1 INVENTOR.

152 22 7 zzfiZffi m 7; g A'ITORNEYS Patented Aug. 10, 1971 3,597,865

2 Sheets-Sheet 2 f j INVENTOR.

ATTITUDE ADJUSTER FOR DRAGLINE BUCKET BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to earth-moving equipment and-more particularly to an attitude adjuster for the bucket of a dragline.

2. Prior Art Dragline buckets are operated primarily by two babies (or sets of cables) or ropes, the dragrope (or ropes) which pulls the bucket forward and the hoist rope (or ropes) which lifts it vertically. The hoist rope (or ropes) is connected to the bucket behind the center of gravity of the bucket so that direct lifting of the bucket by the hoist rope (or ropes) will cause it to tilt forward into a dumping position.

ing a tension on the dragrope prohibits the bucket from being lifted directly under the end of the boom.

The prior art has attempted to minimize these disadvantages by moving the point of attachment of the hoist rope with respect to the center of gravity of the bucket, thereby requiring less tension to retain the bucket in a level position. This solution may create further disadvantages in attempting to dump a partially loaded bucket. The prior art has also attempted to minimize the difficulties by moving the dump sheave, thereby changing the moment arm between the dump rope and the point of attachment of the hoist rope. to the bucket. While this may optimize single placement characteristics for the entirety of bucket operations, it does so at the sacrifice of optimum characteristics at the three separate stages of dumping, loading and lifting.

SUMMARY OF THE INVENTION This invention overcomes these disadvantages by providing a movable dump sheave which automatically adjusts the attitude ofthe bucket during loading and lifting.

In a preferred embodiment, the inventionconsists essen tially of a housing having a support end and a free end with a rod projecting from the free end. The rod is biased by a spring contained in the housing away from the free end. The housing carries a support for the dump sheave. The support end of the housing is attached tothe hoist rope while the rod is attached to the hoist chain. Compression of the spring will allow the rod to move out of the free end of the housing, thereby increasing the distance between the housing and the bucket. This is done in dependent relation to the weight of the bucket and contents. 1

Since the housing carries the dump sheave, the dump rope: 60

can be dimensioned so as to function with optimum characteristics during dumping and loading when the housing will be closest to the bucket and when the bucket is empty.

After loading, when the bucket is lifted by the hoist'rope. the spring will compress increasing" the distance between the end of the hoist rope and the bucket while at the same time moving the dump sheave away fromthe bucket, thereby in ef'- fect shortening the dump rope. This. effective shortening of the dump rope lessens the amount of tension necessary on the dragrope. Therefore, the amount of force necessary to lift the bucket is minimized and the bucket can be lifted from a point closer to the boom end while maintaining the bucket in a nondump position.

Itis therefore an object of this invention to provide a new attitudeadjuster for a dragline bucket.

It is another object of this invention to provide a bucket attitude adjuster for supporting the dump rope sheave in a dragline bucket suspension system.

It is yet another object of this invention to provide an automatic bucket attitude adjuster adapted to move the dump sheave with respect to the bucket in dependent response to the weight of the bucket and contents to reduce the tension necessary to keep the bucket level during hoisting.

It is yet another and more specific object of this invention to provide a spring-tensioned elongatablelink in the hoist rope connection of a dragline bucket to which the dump sheave may be attached and which automatically increases the distance between the dump sheave and the bucket in dependent response to the weight of the bucket and contents during hoisting whereby the tension in the dump rope necessary to keep the bucket level is reduced. v.

Other objects, features and advantages of the present inven-' tion will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a dragline earth-moving machine 10 having a cabin 11 containing the power machinery and cable drums and providing a base for one end of a boom 12. A bucket 13 is suspended from the tip 14 of the boom I2 remote from the cabin by a hoist rope or cable I5 which passes through a boom sheave 16 at the tip 14. The cable 15 is operated by a power drum 16 in the cabin II.

The hoist rope 15 moves the bucket 13 in a vertical direction while a dragrope I8 moves it in a horizontal direction. The dragrope 18 is operated by a powered drum 19 from the cabin 11 and passes through a sheave 20 located at the front of the cabin.

The bucket I3 is attached to the hoist rope 15 by hoist chains 21 attached to hoist trunnions 22 at either side of the bucket. The trunnions 22 are spaced from the center of gravity 23 of the bucket in a direction remote from the front or lip end 24 of the bucket.

The dragrope I8 is attached to the bucket 13 by chains 25 which are fastened by bail fastenings 26 to either side of the bucket adjacent the lip end 24 thereof and normally below the arch 27. The arch 27 spans the distance between the sidewalls of the bucket at the front thereof and is spaced above and nor- 'mally slightly in front of the lip 24. The chains 25 are attached to the dragrope through a fastening such as a crew's-foot 28. The chains 21 are attached to the hoist rope 15 through a member 29 which also serves as a point of attachment for a dump sheave 30 which is either integral with the member 29 or is attached thereto so as to anchorthe dump sheave 30 to the hoist rope 15. A dump rope 31' has one end thereof attached to the dragrope 18 through the crows-foot 28 and the other end thereof attached to the forward part of the bucket suchas the arch 27 at a central point 32 thereof. Although this invention is illustrated as used in connection with a bucket having an arch, it is to be understood that it is equally applicable to other types of buckets including archless buckets having twin dump ropes attached adjacent each sidewall of the bucket.

During operation, the bucket 13 is dropped to the ground at a position approximately below the tip 16 of the boom 12 as is illustrated in position A of FIG. 1. From this position, the bucket 13 is towed forward by the dragrope 18 across the surface 34 to be excavated. During this towing operation, the hoist rope may be slack. The dump rope 31 may also be slack. When the bucket is full, the hoist rope 15 is used to lift it from the surface 34 as is indicated in the position 8 of FIG. 1. Because the trunnions 22 attaching the hoist chains 21 to the bucket 13 are located behind the center of gravity 23, the bucket has a tendency to tip forward which would dump the load. To compensate for this, the dump rope 31 is kept in a state of tension to retain the front of the bucket level with the rear thereof. When it is desired to dump the load as indicated by the position C of FIG. 1, releasing the tension in the dump rope 31 will allow the front of the bucket to tilt.downwardly thereby dumping the load from the bucket.

In order to keep tension in the dump rope 31, it is necessary to keep tension in the dragrope 18. For this reason, it is impossible to lift the bucket from a position directly under the boom without having it tilt forward. The tension in the dump rope 31 is created and dependent upon the existence of tension in the dragrope 18. Tension in the dragrope 18 is, in turn, a function of the weight of the bucket and contents and the angular displacement thereof from a position vertically below the boom sheave 16.

The tension necessary in the dump rope 31 to keep the bucket level is in turn dependent upon the weight of the bucket and contents and the length of the moment arm created by the distance between hoist trunnions 22 and the center of gravity 23. Because the dump line 21 is connected to the bucket at an angle to the horizontal or bucket level, the tension required in the dump rope is also a function of the placement of the dump sheave 30 which creates that angularity.

Inasmuch as it is necessary to be able to adjust the bucket to a level position when empty, the length of the dump rope 31 and positioning of the dump sheave 30 are set so as to optimize the ability to manipulate the bucket into a level position as close as possible vertically under the boom sheave when the bucket is empty. As the bucket is filled, and therefore becomes heavier, the tension necessary in the dump rope to prevent the increasing tilting moment also increases. If it is assumed that the entirety of the tension in the dragrope 18 is transferrable to the dump rope 31 to keep the bucket level, then it can be seen that because of the increase in required tension in the dump rope, the bucket must be moved further and further from the point vertically under the boom sheave. In addition, due to the attachment of the dump sheave 30 to the hoist rope 15, the vertical component of the tension in the dump rope 31 becomes an added force which must be lifted in addition to the weight of the bucket and contents.

This invention provides a device which moves the dump sheave away from the bucket in response to the increase in weight ofthe bucket and contents. When the bucket is empty, the dump sheave is closest to it and this distance measurement together with the length of the dump rope and the angle thereof with respect to the horizontal or level position of the empty bucket may be set for optimum operating conditions. As the weight of the contents of the bucket increases, the sheave moves away from the bucket, thereby increasing the moment arm between the dump rope 31 and the hoist trun nions 22. This increase in moment arm reduces the tension in the dump rope which would otherwise be necessary to keep the bucket level. Reduction in tension from the otherwise normally required tension not only reduces the vertical component added to the lifting force, but also reduces the distance from the vertical which it is necessary to move the bucket in order to obtain the required tension. Thus, through the use of this invention, less force is necessary to lift the loaded bucket and the bucket can be lifted closer to the point vertically below the boom sheave.

In addition, moving the dump sheave with respect to the bucket, in effect, shortens the dump rope section from the sheave to the bucket thereby moving the lip end of the bucket slightly above the level'position. This reverse tilt prevents fallout of loose contents from the front of the bucket during the hoist operation.

FIG. 2 illustrates the attitude adjuster 40 of this invention. The adjuster 40 comprises a housing 41 having a support end 42 and an open end 43. An extensible rod 44 projects from the open end 43. An attachment rod 45 projects at an angle from the housing 41. The hoist cable 15 is attached to the support end 42 of the housing 41 while the hoist chains 21 are attached to the end 46 of the rod 44. The dump sheave 30 is attached to the attachment rod 45.

As illustrated in FIG. 3, in cross section the housing 41 may be cylindrical with the support 42 attached to one end 50 thereof as by welding 51. The open end 43 of the cylindrical housing 41 may be closed by a threaded closure plug 52 which has a central opening 53 through which the rod 44 extends. The end 54 of the rod which is contained in the housing 41 may be threaded as at 55 and carry a slidable abutment 56 retained thereon by a nut 57. The abutment 56, nut 57 and bolt 54 are slidable within the cylindrical housing 41 to the point ofconflict with the plug 52. A coil spring 58 is entrapped between the plug 52 and the block 56 in a partially com pressed state. A portion 59 of the end 46 of the rod 44 is threaded and receives an adjusting nut 60 and locknut 61 thereon. The adjusting nut 60 can be set to limit the distance the rod 44 can be drawn into the housing 41 by action of the coil spring 58. The nut 60 will bottom against a wall 62 of the plug 52.

As the weight on the rod 46 increases, the spring 58 will be further compressed, thereby allowing the end 46 ofthe rod 44 to project further from the housing 41. In this manner, the distance between the end 46 of the rod 44 and the attachment member 45 which may be attached to the housing 41 as by welding 63, increases. Since the hoist chains 21 are suspended from the end 46 of the rod and the dump sheave 30 is attached to the attachment member 45, the distance between the bucket and the dump sheave will increase. This increase in the distance will be a function of the increase in weight caused by filling of the bucket.

The size of the spring 58 and the settings of the nuts 57 and 60 are arranged for optimum operating conditions of the bucket, when empty. Thus, the optimum positioning of the dump sheave 30 is obtained with an empty bucket. As the weight in the bucket increases, the dump sheave 30 will be moved further away from the bucket. This movement will increase the length of the moment arm between the dump rope and the hoist trunnions. The increased moment arm length lessens the amount of tension necessary to retain the bucket in a level position for a given weight.

Because the amount of tension necessary in the dump rope is reduced, a corresponding reduction in the necessary distance from the vertical which the bucket has to be moved by the dragrope in order to produce the tension in the dump rope, is also reduced. This allows the dragline bucket to operate closer to a point vertically under the boom sheave. Additionally, as the tension in the dump rope is comparatively reduced, the vertical correspondent thereof is also reduced, thereby lowering the force necessary to lift the loaded bucket.

The spring 58 can be chosen with optimum characteristics in mind over the entire range of probable bucket load and blocks can be inserted between the coils of the spring to limit compression if necessary. Alternately, a plurality of concentric springs can replace the single spring illustrated in FIG. 3. The plurality of springs can have different compression ratios so as to provide a nonlinear graph of rod displacement as a function of bucket weight. Additionally, the spring 58 could be replaced by other devices having the same variable length and resistance to change thereof such as for example hydraulic piston devices.

lt is a particular feature of this invention that due to the provision of the adjusting nuts 57 and 60 the initialtensioning and positioning of the rod end 46 with respect to the suspen- I a of the bucket.

FIG. 4 illustrates another embodiment of this invention wherein the dump block 65 is made integral with the housing 41 of the attitude adjuster.

FIG. is a fourth vector diagram illustrating the effect of my invention under assumed conditions.

The point 70 represents a point on the boom of a dragline equivalent to the boom sheave 16 of FIG. 1. The line 71 represents the hoist rope l5 and is attached to a block 72 representative of the bucket 13 at a point 73 representative of the hoist trunnions-22. The center of gravity of the block 72 is represented at point 74 spaced from the trunnion point 73. The line 75 represents that portion of the dump rope between the sheave 76 and the bucket 72. The line 77 represents that portion of the dump rope extending between the sheave 76 and the dragrope 78.

if it is assumed that the weight W of the loaded bucket 72 is 150,000 lb. and the distance D, from the trunnion point 73 to the center of gravity 74 is in. and the distance D from the trunnion point 72 along a line perpendicular to the line 75 and terminating at the line 75'is 140 in., then the forces needed to lift the bucket in a level position can be computed as follows:

The force (A) tending to tilt the bucket from a level position is created by the offcenter positioning of the trunnion point 73 from the center of gravity 74. The measurement of this moment arm force is A=D,XW 50,000 lb. x 30 in. =4,500,000 lb./in.

A is also the force which must be overcome by the tension in line 75. The tension necessary in the line 75 is represented by the formula T=WD wherein D is the measurementofa moment armfrom the line 75 to the pivot ortrunnion point 73. Therefore: a

T=4,500,000 lb./in. 140 in.

T=32,000 lb.

Thus, the tension in the dump rope is 32,000 lb. Because the dump rope is attached to the hoist rope 71 at the sheave76,

\ this tension force acts against the hoist rope to the extent of its vertical coefficient B.

The vertical coefficient B can be computed with reference to the angle 0 and is applicable to tension in the line 77. The angle 0 represents the angle between the line 77 and the horizontal. This angle is assumed to be 30 for purposes of this example. Further. the tension in line 75 is assumed to completely be absorbed within the bucket-righting system and therefore does not influence outside forces. The vertical coefficient B is then equal to the tension in the rope 7 l,sin 0.

B=1Xsin 0 B;32,000 lb.x0.500 B=16,000 lb.

Therefore, the total tension necessary in the hoist rope to lift the bucket H, is W+E or 166,000 lb.

The line 80 represents the hoist force H, where the line 81 extending at right angles to the line 80 from the line 80 to the center of gravity 74 represents the horizontal force acting against the bucket 72 by the dragrope 78. If it is assumed that through the rope 77 to the dragrope 78, then the drag tension D, represented by line 8] equals 32,000 lb. As mentioned above, the horizontal tension H,=l66.000 lb. Therefore:

Tan =D,/H, Tan d =32,000 lb./l 66,000 lb. =0.l93

. the entirety of the tension in the dump rope 75 is transferred 1f the verticalheight P of the hoist sheave 70 from the trunnion point 73 is 129 ft., then the distance M which the dragline 78 must move the bucket 72 from vertical in order to achieve T is as follows:

Thus, a bucket having a full weight of 150,000 lb. must be moved a distance of approximately 25 ft. from vertically below the boom sheave in order to create the necessary 32,000-lb. tension in the dump rope so that the bucket may be lifted by the hoist rope in a level position.

If it is assumed that the positioning of the sheave 76 in FIG. 5 represents the optimum positioning of that sheave for an empty bucket, and if it is assumed that the rod movement of the attitude adjuster of this invention between an empty bucket and a bucket load of 150,000 lb. is 2 ft., the following comparison can be made.

The new positioning of the dump sheave 76 is 76' and the positioning of the lines and 77 are indicated at 75 and 77'. The distance of the vertical shift Vs between 76 and 76' equals 24 in. If it is assumed that practically all of this shift is represented in an increase of the moment arm from D; to D then becomes 164 in. Therefore:

T#,S00,000 ft./lb. 22, A'=4,500,000 lb./in./l64 in. A'=27,400

The vertical component B of A therefore equals 0.50XA' which equals 13,700 lb. Thusljt is equal to W+B' or 163,700 1b., a saving of 2,300 lb. attributable to use of the device.

Substituting A for M and H, for H,, the tangent of 4 then becomes 27,400l63,700 or approximately 0.167. Therefore, is 9.5".

M'=0. l 67Xl29 ft. or approximately 20.8 ft. This represents a savings of approximately 4 ft. or 12 percent less that the dragline will have to move the bucket fromthe vertical before lifting at a level position.

Additionally, if it is assumed that the dump rope is approximately 50ft. long and the length between the bucket arch and the dump sheave is approximately 13 ft., movement of the dump sheave 24 in. would effect an approximate l2-in. rise in the plane of the bucket. For a 30cu.-yd. bucket having a length of in., this would represent a 7.5 percent upward slope.

It can therefore be seen that my invention reduces the force necessary to lift a given load in a dragline bucket while at the same time reducing the horizontal movement necessary to maintain the bucket in a level position. In addition, my invention provides a method whereby the fully loaded bucket is automatically tilted upward from the horizontal when lifted. This reduces the amount of spillage from the front of the bucket during hoisting.

Although I have set forth the teachings of my invention with respect to certain theories and drawings, it is to be understood that these are for illustrative purposes only and that others may wish to utilize my invention in different embodiments.

I claim as my invention:

1. A dragline bucket suspension and dump assembly comprising: a drag bucket, said bucket having a front opening and a closed rear and side and bottom walls, said bucket having one and only one hoist chain attachment point on the exterior of each sidewall, said points positioned to the rear of the center of gravity of the bucket in both its empty and fully loaded states, each hoist chain having one end thereof attached to one attachment point and the other end thereof attached to a first portion of an extensible device, a second portion of said extensible device affixed to a hoist rope, means for changing the distance between the said first portion point of attachment to; the said hoist chains and the said second portion, a dump sheave attached to the said second portion, a dragrope attached to said bucket controlling horizontal movebe positioned at a predetermined distance from the said bucket when the said bucket is empty, the said extensible device operatable thereafter to increase the distance in dependent response to increased bucket weights.

3. The assembly of claim 1 wherein the said means includes a compressible spring interposed between the bucket and dump sheave.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 597, 865 Dated August 10 197 Inventor(s) Henry Rumfelt It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 5, line 42, "T =WD should read: -T W+D Col. 5, line 45, "T 4,500, 000 lb. /in. 140 in. should read: -T =4,500, 000 1b./in.--l40 in.

Signed and sealed this I th day of April 1972.

(SEAL) Atte st:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents RM PO-105O (10-89] USCOMM-DC GOING-P69 a u s sevzmmim PRINTNG OFFICE 19a: o-35s-334

Claims

1. A dragline bucket suspension and dump assembly comprising: a drag bucket, said bucket having a front opening and a closed rear and side and bottom walls, said bucket having one and only one hoist chain attachment point on the exterior of each sidewall, said points positioned to the rear of the center of gravity of the bucket in both its empty and fully loaded states, each hoist chain having one end thereof attached to one attachment point and the other end thereof attached to a first portion of an extensible device, a second portion of said extensible device affixed to a hoist rope, means for changing the distance between the said first portion point of attachment to the said hoist chains and the said second portion, a dump sheave attached to the said second portion, a dragrope attached to said bucket controlling horizontal movement thereof, a fixed length dump rope having one end thereof attached to the dragrope and the other end thereof attached to the bucket forward of the center of gravity, said dump rope passing through the said dump sheave, and the said means responsive to weight changes in the bucket and contents.

2. The assembly of claim 1 wherein the said extensible means is selectively adjustable whereby the said sheave may be positioned at a predetermined distance from the said bucket when the said bucket is empty, the said extensible device operatable thereafter to increase the distance in dependent response to increased bucket weights.