US 3570152 A
Description (OCR text may contain errors)
MalCh 16, 1971 K, w, SQHUERMANN ETAL 3,570,152
CRUMBING TOOL FOR TRENCHING MACHINES Filed Jan. '7, 1969 INVENTORS EDWIN G. MALZAHN KENNETH W. SCHUERMANN United States Patent Oihce 3,570,152 CRUMBING TOOL FOR TRENCHING MACHINES Kenneth W. Schuermann and Edwin G. Malzahn, Perry, Okla., assignors to The Charles Machine Works, Inc. Filed Jan. 7, 1969, Ser. No. 789,452 Int. Cl. E02f 5/06 U.S. Cl. 37-86 8 Claims ABSTRACT OF THE DISCLOSURE A crumbing tool adapted to be connected to the digging boom of a ditching or trenching machine by an adjustable four-bar linkage. When a ditch is being dug, the four-bar linkage permits the crumbing tool to enter the ditch and follow the digging boom down to the desired digging depth. In addition, the amount of down pressure applied by the crumbing tool against the bottom of the ditch is variable by adjusting the relationship between the members of the four-bar linkage.
FIELD OF THE INVENTION This invention relates to crnmbers and more particularly to a crumbing tool which is to be connected to the digging boom of a ditching or trenching machine.
BACKGROUND OF THE INVENTION Crumbers are principally used to augment earth working equipment such as ditch digging machines by trimming ditches as they are dug. Trimming comprises squaring off the sides and bottom of the ditch whereupon loose material not initially brought to the surface by the digging chain is drawn along the ditch. Preferably the crumbing tool is connected to the ditch digging machine so that it will be drawn along the bottom of a ditch behind the digging boom.
For the most part, crumbing tools known heretofore have been rather complicated heavy pieces of equipment with numerous adjusting devices and complex mounting trusses or they have been so simple that they were fixed immovably to the ditching machine. While the former type of device may include means for automatically lowering a crumber to follow the digging boom into a newly formed ditch, the latter, simpler device must be manually lowered and set to the proper depth after the ditch is begun. Therefore, if a crumber of simple construction is utilized, the operator must dismount from the ditching machine to adjust the crumber to the proper depth. If the ditch is to have a variable depth then the operator will have to repeatedly stop the machine, dismount and adjust the depth of the crumbing tool in accordance with the depth of the ditch.
In addition, it is often desirable to be able to adjust the downward pressure applied by the crumbing tool against the bottom of the ditch to respond to various soil conditions that may be encountered. While digging, the amount of pressure on the bottom of the ditch applied by crumbers known in the prior art can only be adjusted by adding weights to the crumbing tool or by the construction of elaborate adjusting means. These devices for adjusting the pressure contribute toward making the machine costly and ineiiicient since any weight or any heavy apparatus `which is to be connected to the crumber in order to increase the pressure it applies against the bottom of the ditch must necessarily add to the weight of the digging machine thus making it less eicient. Further, the devices of the prior art are very inconvenient and cause much time to be lost since the weights have to be carried from place to place and then added to the crumber when it is operative and removed when it is transported.
3,570,152 Patented Mar. 16, 1971 SUMMARY OF THE INVENTION Generally the invention comprises a crumbing tool to be attached to the digging boom of a ditching machine including an elongated arm adapted to be mounted on the digging boom in overlying relation thereto; and a crumbing shoe connected to the elongated arm so that it will be disposed rearwardly of the boom. Means are provided for constraining the elongated arm for curvilinear movement relative to the digging boom whereby the crumbing shoe is caused to move forwardly in response to downward movement of the digging boom to enter a newly formed ditch and move rearwardly and down to drag on the ditch bottom as the ditching machine moves forward. The constraining means also is adjustable to vary the pressure exerted by the crumbing shoe against the bottom of the ditch.
BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational View of a vehicle carried ditcher having a crumbing tool with the tool and ditching boom shown resting on the surface of the earth prior to the commencement of a digging operation;
FIG. 2 is a side elevational view of the machine shown in FIG. 1 showing the relative positions of the crumbing tool and the digging boom when the digging of a ditch is initiated; and
FIG. 3 is a side elevational view of the machine shown in FIGS. 1 and 2 showing the relative positions of the crumbing tool and digging boom as the ditch digging progresses.
As shown schematically in FIG. 1, a suitable digging chain 14 is entrained about sprockets 16 and 18 which are rotatably carried at each end of digging boom 12. Preferably a suitable supporting base 15 on the digging boom 12 serves as a mounting for the crumbing tool. It is to be understood, however, that brackets of a suitable construction may be utilized in lieu of the base shown, or if desired the crumbing tool may directly be connected to boom 12. The ditching or trenching mechanism is mounted by an appropriate pivotal connection at 13 on a suitable mobile base such as vehicle 20 having supporting wheels 22 to propel the ditching machine along in digging a ditch.
The crumbing tool 10 comprises an elongated arm 30 disposed in overlying relation to the boom 12. A crumbing shoe 32 connected to one end of the elongated arm 30 and adapted to trail behind the rearmost sprocket 18 of the digging boom has a bottom edge 34 which is adapted to engage the bottom of the ditch in scraping relation therewith.
While the crumbing shoe herein is illustrated schematically and is deemed to be only indicative of the configuration of such a member it is apparent that any suitable scraping means known to those skilled in the art may be advantageously employed. However, preferably the crumbing shoe should have a rearwardly and downwardly projection concave or arcuate configuration as shown on the drawing.
A sleeve 36 having generally the same cross sectional configuration as elongated arm 30 is disposed in sliding relation thereto on an intermediate portion thereof. One end of an arm 46 is connected to the sleeve by a suitable pivot 50. At its other end arm 46 is connected to supporting base by means of pivot 4'8. A second sleeve 38 is fixed to elongated arm 30 in spaced relation to sliding sleeve 36. Connected to sleeve 38 at pivot 42 is arm 40 which is connected at its other end to supporting base 15 by means of pivot 44. Pivots 44 and 48 on supporting base 15 are disposed in fixed spaced longitudinal relation to each other. While the spacing of pivots 44 and 48 is not critical it will be observed that the spacing should be substantial relative to the lengths of arms 40 and 46 in order for the device to operate in accordance with its intended purpose. In the preferred form of the invention arm 46 is slightly shorter than arm 40, however, as will be apparent, the relative lengths of the arms are not critical and the device would be operable, although its effectiveness would be reduced, if arms 40 and 46 were the same length or if arm 46 were slightly longer than arm 40.
Adjusting means 58 has one end pivotally connected at 60 to an ear 62 on sliding sleeve 36 while its other end is connected to a suitable housing 64 on fixed sleeve 38. Preferably the adjusting member 58 is a screw adjuster which is operable by crank 70; however, alternative adjusting members such as hydraulic or electrical adjusting means could also be employed.
It should be observed that the structure described above defines an adjustable four-bar linkage comprising arms 40 and 46 diverging toward elongated arm 30, supporting base 15 and the portion of elongated arm 30 between pivots 42 and 50. The configuration of the linkage and the position of elongated arm 30 relative to digging boom 12 can be altered by moving pivots 42 and 50 either closer together or further apart by the use of adjusting means 58. The minimum spacing to which pivots 42 and 50 can be brought to is predetermined by the dimensions of sleeves 36 and 38 since stop 66 on sliding sleeve 36 will be engaged by stop `68 on fixed sleeve 38 when the minimum distance is reached. Preferably the stops should be arranged so that the minimum distance between pivots 42 and -50 will be greater than the distance between pivots 44 and 48 so that there will always be some divergence between arms 40 and 46.
The four-bar linkage interconnecting the digging boom 12 and the elongated arm 30 constrains the elongated arm and crumbing shoe 32 for curvilinear motion relative to boom 12 about an instant center 72 which is located at the theoretical intersection of the axes of arms 40 and 46. For a ditch of uniform depth such as the ditch illustrated in FIG. 3, the locus of all instant centers 72, 72', 72", etc., is on a straight line extending from arm 40. A particular instant center is located by the intersection of the aforementioned line by a second line extending from arm 46.
When stops 66 and 68 abut each other pivots 42 and 50 are spaced slightly further apart than pivots 44 and 48 so that bars 40 and 46 diverge toward elongated arm 30 and instant center 72 is further from the digging boom than where shown in FIG. 1. If the spacing between pivots 42 and 50 is increased from that shown in FIG. 1, instant center 72 moves closer to the digging boom than shown in FIG. 1. As will be explained in greater detail this adjustability of the location of the instant center 72 contributes to a mechanical advantage which enables the pressure applied by the crumber shoe 32 to the bottom of the ditch to be adjusted and regulated.
In operation, the crumbing tool is initially in the position shown in FIG. 1 wherein it is in engagement with the surface which is to be penetrated by the digging chain 14 with contact point 34 of the crumber shoe 32 lying rearwardly of sprocket 18. When the digging begins, the digging boom 12 begins a counterclockwise rotation about pivotal connection 13 on vehicle 20 as it begins to dig the ditch. However, since the crumbing shoe 32 is to the rear of the ditch when started, it remains supported by the surface 75 adjacent thereto. This results in an upward force being applied to the crumbing shoe 32 causing it to shift forward relative to the digging boom 12. As the digging boom continues to sweep counterclockwise as it penetrates the earth the crumbing shoe 32 continues its forward movement until it reaches the opened ditch 74 as shown in FIG. 2.
In FIG. 2 the crumbing shoe 32 is seen to overlie rear sprocket 18 as it follows that sprocket downwardly along the arcuate path defined by the digging boom 12 as it rotates downwardly into the ditch. Since the natural tendency of the crumber is to shift downwardly and rearwardly, it falls into sliding engagement with the rear wall 76 of the ditch. If the crumbing shoe 32 is rounded as described above, its sliding movement against rear wall 76 is accomplished with relative ease.
In FIG. 3 the digging chain and crumbing tool are shown in their normal working position after the ditch has been opened to the desired depth. Since the crumbing shoe 32 is not restrained by rear wall 76, it falls downwardly and rearwardly to its natural position against the bottom 78 of the ditch. While in this position it is drawn behind the ditching machine to trim the sides and bottom of the ditch just cut.
The longitudinal load imparted by forward movement of the pulling vehicle 20 `which is felt by the digging boom 12 through its pivotal connection 13 with the pulling vehicle 20 as it is moved forward through the ditch is transferred to elongated arm 30, through arms 40 and 46. However, the load in these arms, although applied at pivots 44 and 48, acts as though it were a load applied at the instant center 72, but in the same direction as the load felt by the digging boom at pivot 13.
It is clear that for a steady load at pivot 13 from the forwardly moving vehicle `20, as the distance from the elongated arm 30 to the instant center is increased to instant center 72'l the amount of pressure applied by the crumber shoe 32 against the bottom of lthe ditch 78 will be increased and as the distance to the instant center is decreased to instant center 72 the amount of pressure applied by the crumber shoe 32 will be decreased.
Thus while in the position shown in PIG. 3 the downward pressure applied by the crumber shoe to the bottom of the ditch 78 can be regulated by controlling the relative positions of pivots 42 and 50 and consequently the angular relation of arms 40 and 46 to move the instant center 72 away from or toward elongated arm 30. Consequently, the pressure applied to the bottom of the ditch is the greatest when arms 40 and 46 are substantially parallel and is the least when the angle between those arms is at its maximum.
While the invention described herein has been described with reference to a preferred embodiment, it is to be understood that the embodiment of the invention shown herein is merely exemplary and that other forms and other embodiments of this invention will be apparent to others who are skilled in the art. Accordingly, the scope of the invention should not be limited by the foregoing description but rather should be defined only by the scope of the claims which are appended hereto.
What is claimed:
i1. A crumbling tool to be attached to the digging boom of a ditch digging machine comprising an elongated arm having means for mounting it on said boom in overlying relation thereto;
a crumbing shoe connected to said elongated arm so that it will be disposed rearwardly of said digging boom; and
means for constraining said elongated arm for curvilinear movement relative to said digging boom including nonparallel link means pivotally connected to said elongated arm, said link means having means remote from said elongated arm for said link means to be pivotally connected to said digging boom whereby said crumbing shoe is caused to move forwardly in response to down-ward movement of said digging boom as it starts to dig a ditch. ,Y
2. A tool as defined in claim lwherein said pivotally connected means includes at least two link arms, each of said link arms being pivotally connected at one end to said elongated arm by pivot means disposed in spaced longitudinal relation along said elongated arm and having pivot means to be pivotally connected at their other ends to said digging boom, said link arms being arranged so that they diverge toward said elongated arm.
3. A tool as dened in claim 1 wherein said constraining means include adjusting means to vary the pressure exerted by said crumbing shoe against the bottom of the ditch.
4. A tool as dened in claim 3 wherein said constraining means includes at least two link arms, each of said link arms being pivotally connected at one end to said elongated arm by pivot means disposed in spaced longitudinal relation along said elongated arm and having pivot means to be pivotally connected at their other ends to said digging boom, said link arms being arranged so that they diverge toward said elongated arm.
5. A device as dened in claim 4 wherein said adjusting means is interconnected between said link arms, said adjusting means being operative to vary the amount of divergence of said link arms whereby the pressure exerted by said crumbing shoe may be varied.
6. A device as dened in claim 5 including sleeve means slidably mounted on said elongated arm;
one of said link arms being pivotally connected to said sleeve means for movement therewith; and
said adjusting means being operative by sliding said sleeve means relative to said elongated arm.
7. A tool as dened in claim 6 -wherein said adjusting means includes extensible means connected between said sleeve means and said elongated arm so that actuation of said extensible means causes said sleeve means to move relative to said elongated arm.
-8. A tool as defined in claim 7 wherein stop means are disposed on said elongated arm to predetermine the minimum amount of divergence between said link arms.
References Cited UNITED STATES PATENTS ROBERT E. PULFREY, Primary Examiner C. D. CROWDER, Assistant Examiner U.S. C1. X.R. 172-739