US3627156A - Torque balancing linkage for excavator dipper sticks - Google Patents

Abstract

A dipper stick is adjustably mounted in a saddle which is pivoted to upstanding brackets at the outer end of the boom of an excavating machine, there being an hydraulic cylinder pivoted at one end to the boom and having a piston rod projecting from its other end and connected to the lower converging ends of two sets of links. One set of links acts as a radius rod and has its upper ends pivotally connected to upper portions of the boom brackets inwardly of the pivotal connection for the saddle, and the other set of links has its upper ends pivotally connected to the saddle outwardly of the pivotal connection for the saddle.

Description

0 United States Patent [in 3,627,156

[72] Inventor Roy 0. Billings 3,143,228 8/1964 Billings 2 l4/l47 6621 West Wisconsin Ave., Milwaukee, 3,220,578 1 1/1965 Pilch 214/138 Wis. 53213 3,253,724 5/1966 Marner 214/138 [2]] Appl 859361 Primary Examiner-Gerald M Forlenza [22] Flled Sept 1969 Assistant Examiner.lerold M. Forsberg [45] Patented 1971 Attorney-Morse" & Morsell [541 TQRQUE BALANCING LINKAGE FOR ABSTRACT: A dipper stick is adjustably mounted in a saddle EXCAVATOR F STICKS which is pivoted to upstanding brackets at the outer end of the 1 Claim 5 Drawing boom of an excavating machine, there being an hydraulic [52] [1.8. Ci 214/147 G, Cylinder pivoted at one end to the boom and having a piston 214/]35 rod projecting from its other end and connected to the lower [51] Int, Cl B66 1/00 converging ends of two sets of links. One set of links acts as a 50] Field of Search 2 14/135, radius rod and has its upper ends pivotally connected to upper 137, 138, 147 portions of the boom brackets inwardly of the pivotal connection for the saddle, and the other set of links has its upper ends References Cited pivotally connected to the saddle outwardly of the pivotal con- UNITED STATES PATENTS nection for the saddle. 3,l29,83l 4/1964 Mrozek 2l4/l37 BMZTIASG Patented Dec. 14, 1971 3 Sheets-Sheet 1 INVENTOR ROY O BILLINGS 4% ATTORNEYS Patented Dec. 14, 1971 3 Sheets-Sheet 2 INVENTOR ROY O. BILLINGS BY MW ATTORNEYS Patented Dec. 14, 1971 3 Sheets-Shoot (6 ATTORNEYS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is adapted for use in excavating machines of the type having a clipper stick for supporting a clamshell bucket or other earth moving device.

2. Description of the Prior Art For many years the crowd" motion of a dipper stick has been under the control of cables operated from the cab. Typical of this type of construction is Darrah, US. Pat. No. 1,954,119. In my prior US. Pat. Nos. 3,219,212, 3,143,228 and 3,143,229, hydraulic rams are employed and there are crowd" cylinders having lower ends pivotally connected to the boom and having extensible rods with outer ends pivotally connected directly to the dipper stick saddle. With this type of arrangement, as the dipper stick saddle swings on its pivot relative to the boom to raise the dipper stick toward a position where it effects a greater angle with respect to the boom, the effective leverage of the crowd cylinder rod lessens as the dipper stick is elevated so that when the dipper stick is pushed upwardly from a normal working position the effective leverage is the poorest, this being at a time when the torque demand is the greatest. Thus it has been necessary to use an hydraulic cylinder of relatively large size to produce sufficient power. Furthermore, with the arrangement of my prior patents, in certain positions of adjustment, excessive strains are placed upon the outer end of the cylinder. In addition, with the arrangement of my prior patents, the cylinder has, in certain positions of adjustment, protruded from the lower portion of the boom. Such protrusion is undesirable as there is a possibility of damage to the cylinder during operation.

SUMMARY OF THE INVENTION The present invention includes, in an excavating device being a boom with a dipper stick saddle pivoted to upstanding brackets near its outer end, and having a crowd cylinder pivotally connected at its head end to the boom and having a piston rod projecting from its opposite end, torque balancing linkage connected between the end of the rod and the boom brackets and saddle and arranged to equalize stresses during the crowd" action and to maintain the hydraulic thrust closer to a straight line action.

A general object of the invention is to provide, in a device of the class described torque balancing linkage arranged to minimize the reduction in leverage which normally occurs when the dipper stick is being swung toward a position of parallelism with the boom.

A further object of the invention is to provide torque balancing linkage which minimizes the amount of swing of the hydraulic cylinder during operation whereby the cylinder maintains a position substantially within the confines of the boom.

A further object of the invention is to provide torque balancing linkage for controlling the dipper stick movement which is arranged to provide increased leverage When it is most needed, thereby permitting efficient operation even when the dipper stick is in its maximum extended position in the saddle.

A further object of the invention is to provide, in a device of the class described, improved torque balancing linkage which makes it practical to employ a crowd" cylinder of less size than would otherwise be necessary.

A further object of the invention is to provide, in a device of the class described, improved torque balancing linkage which maintains the effective lever arm" for controlling the crowd" action of the dipper stick closer to a constant length throughout the entire stroke of the crowd" cylinder.

With the above and other objects in view, the invention consists of the improved torque balancing linkage for excavator dipper sticks, and all of its parts and combinations, as set forth in the claims, and all equivalents thereof.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, designating one complete embodiment of a preferred form of the invention, in which the same reference numerals designate the same parts in all of the views:

FIG. 1 is a side elevational view ofan earth working device of a type having an adjustable dipper stick supporting a clamshell bucket;

FIG. 2 is a fragmentary side elevational view showing the outer end of the boom, and showing; a portion of the dipper stick extending through the saddle, the saddle and dipper stick being in a position close to parallelism with the boom;

FIG. 3 is a bottom plan view of the structure illustrated in FIG. 2, the dipper stick being omitted;

FIG. 4 is a view similar to FIG. 2 showing the saddle swung to an intermediate position which is advanced in a downward direction from the position of FIG. 1, parts being broken away; and

FIG. 5 is still another view showing the saddle in an extreme crowd" position with the ram fully retracted.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings, the numeral 20 designates the tractor portion of an earth working device, which device has a turntable 21 supporting a pivoted boom 22, there being an hydraulic cylinder 23 having a telescopic piston rod 2d pivoted at its outer end to the boom for controlling the boom angle.

As is clear from FIG. 3 the boom includes spaced side members 25 and projecting upwardly from the top of each side member is an upstanding bracket 26, as shown in FIG. 2. A pivot pin 27 which connects upper forward portions of the brackets 26 serves as the means by which a saddle 28 is pivotally supported on the boom 25 in the manner shown in FIGS. 2 and 3. The ends of the pin 27 extend through the lower ends of reinforcing ribs 29 on side portions 30 of the saddle, the saddle being generally U-shaped in cross section as shown in FIG. 3. A fluid pressure operated cylinder 31 has its head end pivotally connected between the sides 25 of the boom as at 32 (FIG. 1). The cylinder has a telescopic piston rod 33 projecting from the usual hydraulically actuated piston. This cylinder may be hereinafter termed a crowd" cylinder, and is operated in the usual manner under control of a valve in the cab.

Adjustably mounted in the saddle for extensible movement is a dipper stick 34 which adjustably carries an earth working tool such as a clamshell bucket 35 on its lower end. Any suitable means may be provided for causing extension and retraction of the dipper stick 34 in its saddle 28. Inasmuch as this forms no part of the present invention the operating mechanism for such extensible movement will not be described.

Torque Balancing Linkage Radius links 36 have upper ends rigidly connected to a sleeve 37 which is adapted to rock on a pivot rod 38 which connects upper rear portions of the brackets 26. The lower ends of the links are connected by a crank pin 39 which extends through a bearing 40 at the outer end of the piston rod 33. Thus the radius rods maintain the pin 39 in the path of the arc a during movement of the piston rod 33 and it is to be noted that the are a is substantially within the confines of the boom. Power-transmitting links 41 have their upper ends pivoted on a pin 42 which extends between the sides 30 of the saddle 28. The lower ends of the links 41 are pivoted to the outer end of the piston rod 33 and to the lower ends of the radius links 36 by means of the pin 39, as shown in FIGS. 2 and 3.

Projecting downwardly beyond the sides of the saddle are stop projections 43 having end recesses 44 shaped to fit the boom bosses 45 (HQ 3) when the dipper stick is in the fully elevated position of FIG. 2. These extensions form a suitable stopagainst further movement. Other convenient stop arrangements may of course be employed.

OPERATION When it is desired to crowd" the dipper stick the fluid pressure operated ram may be actuated,,through any suitable control valves in the cab, to cause retraction of the piston rod 33 from the fully extended position of FIG. 2. During such action the ram 33 will exert a pull to the left on the lower end of the links 41 and, due to the radius links 36, the pivot point 39 will travel in the are a. FIG. 1 shows a position wherein the dipper stick is swung slightly downwardly from the position of FIG. 2. Further retraction of the ram will bring the dipper stick to the angular position shown in FIG. 4 which is a typical working position. FIG. shows a fully crowded position where the ram is completely retracted in the cylinder 31.

During reverse or elevated movement of the dipper stick the improved linkage creates maximum leverage when most needed. At the start of extension movement of the ram from the position of FIG. 5 there will be a push exerted on the pivot point 42 through the linkage 41. As the extension continues the parts will assume the position shown in FIG. 4. Further movement will bring the parts to the position of FIG. 1, and still further movement to the final position of FIG. 2. According to prior practices where the piston rod 33 was connected directly to a saddle, there was the problem of interference from the saddle pivot 27, and during movement from the position of FIG. 4 to the position of FIG. 2 where the torque demand is the greatest, the effective leverage has decreased.

With the present invention, due to the novel linkage arrangement, the effective lever arm indicated at b in FIGS. 2, 4 and 5 is maintained at a substantial length through the range of movement. This distance b is the distance of the pivot point 27 above the axis of the piston rod 33, measured as indicated at b. It will be noted from FIG. 5 that in the fully crowded position the distance b is at its minimum. However, it is still of substantial length and on extension movement of the piston rod from the position of FIG. 5 there is a minimum power demand at the start. When the dipper stick arrives at approximately the position of FIG. 4 the lever arm" distance b is the largest and this is highly desirable because in swinging the dipper stick upwardly from the position of FIG. 4, with the clamshell bucket loaded, a maximum amount of power is required. This lever arm" distance b, of course, diminishes at the extreme position shown in FIG. 2, but it is seldom necessary to swing the dipper stick as far as the position of FIG. 2. Furthermore, in all of the positions illustrated, including the position of FIG. 2, the I ever arm length b is nevertheless substantial. With prior constructions, where there was a direct connection between the end of the piston rod 33 and the saddle, effective leverage diminished to nearly zero in the position of FIG. 2. With this arrangement the ram maintains a substantially straight thrust in all portions of movement. It is also apparent from FIGS. 2, 4 and 5 that the cylinder 31 pivots only a minor amount on its pivot 32 and always stays substantially within the confines of the boom. By maintaining a relatively straight thrust, and a minimum amount of pivot movement of the cylinder there is less stress on the end of the cylinder during operation. The improved torque balancing linkage equalizes stresses throughout the range of movement. As a result a smaller cylinder 31 may be employed than would otherwise be necessary, and the device will still have ample power to elevate the dipper stick when the bucket is filled and when the dipper stick is in an extended position. With prior arrangements there was substantially reduced leverage just when the demand was greatest.

It is to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

What I claim is:

1. In an earth moving machine having a boom with spaced side members at its outer end, said side members having spaced upstanding outer end projections, a saddle pivotally connected between said space upstanding pro ections of the side members of the boom to normally project thereabove, a dipper stick slideably adjustably carried in said saddle, a fluid pressure operated cylinder pivotally connected at its inner end to the boom to extend generally longitudinally thereof and having an extensible piston rod projecting outwardly toward the outer end of the boom, the improvement comprising power-transmitting linkage pivotally connected at one end to the piston rod and at its other end to the saddle at a location above the piston rod and spaced longitudinally outwardly from the pivotal connection between the saddle and the upstanding projections of the boom, radius linkage pivotally connected at its upper end to the upstanding projections of the boom inwardly of the pivotal connection between the saddle and said projections and having its lower end connected to the piston rod adjacent the pivotal connection between the piston rod and said power-transmitting linkage, both the powertransmitting linkage and the piston rod extending in the same general as the longitudinal axis of the boom when the dipper stick is in an inwardly crowded position, and the power-transmitting linkage being movable upwardly at a progressively increasing angle with respect to the axis of the boom as the dipper stick is raised whereby the effective lifting force from the piston rod is augmented as the demand for power increases during elevation of the dipper stick and saddle to a position of parallelism with the boom, wherein, when the piston rod is fully extended, the length and position of the radius linkage is such as to maintain the cylinder and its piston rod substantially within the confines of the side members of the boom while the dipper stick is substantially parallel with the boom, and wherein the length and position of the radius linkage is such as to maintain the arc of swinging movement of the pivotal connection between the end of the piston rod and the linkage such that said pivotal connection stays substantially within the confines of the side members of the boom in all positions of movement.

t i i t i

Claims (1)

1. In an earth moving machine having a boom with spaced side members at its outer end, said side members having spaced upstanding outer end projections, a saddle pivotally connected between said spaced upstanding projections of the side members of the boom to normally project thereabove, a dipper stick slideably adjustably carried in said saddle, a fluid pressure operated cylinder pivotally connected at its inner end to the boom to extend generally longitudinally thereof and having an extensible piston rod projecting outwardly toward the outer end of the boom, the improvement comprising power-transmitting linkage pivotally connected at one end to the piston rod and at its other end to the saddle at a location above the piston rod and spaced longitudinally outwardly from the pivotal connection between the saddle and the upstanding projections of the boom, radius linkage pivotally connected at its upper end to the upstanding projections of the boom inwardly of the pivotal connection between the saddle and said projections and having its lower end connected to the piston rod adjacent the pivotal connection between the piston rod and said power-transmitting linkage, both the power-transmitting linkage and the piston rod extending in the same general direction as the longitudinal axis of the boom when the dipper stick is in an inwardly crowded position, and the power-transmitting linkage being movable upwardly at a progressively increasing angle with respect to the axis of the boom as the dipper stick is raised whereby the effective lifting force from the piston rod is augmented as the demand for power increases during elevation of the dipper stick and saddle to a position of parallelism with the boom, wherein, when the piston rod is fully extended, the length and position of the radius linkage is such as to maintain the cylinder and its piston rod substantially within the confines of the side members of the boom while the dipper stick is substantially parallel with the boom, and wherein the length and position of the radius linkage is such as to maintain the arc of swinging movement of the pivotal connection between the end of the piston rod and the linkage such that said pivotal connection stays substantially within the confines of the side members of the boom in all positions of movement.

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