US1898453A - Boom feet for excavators - Google Patents

Description

Feb. 21, 1933. w LEHMAN ET AL 1,898,453

BOOM FEET FOR EXCAVATORS Filed Nov. 5, 1928 2 Sheets-Sheet l .52 M .54 241 231 g ze 5 Fl: H 45 VENTOR5 ATTORNEYS.

Feb. 21, w L HM ET AL 1,898,453

BOOM FEET FOR EXCAVATORS Filed Nov. 3, 1928 2 SheetsSheet 2 IN VEN TORS,

BYMWI'JWW ATTORNEYS.

Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE WERNER LEHMAN AND MITCHELL L. FYKSE, OF SOUTH MILWAUKEE, WISCONSIN, AS- SIG-NORS T0 BUC'YRUS-ERIE COMPANY, OF SOUTH MILWAUKEE, WISCONSIN, A COR- PORATION OF DELAWARE BooM rrJEr ron EXOAVATORS Application filed November 3, 1928. Serial No. 317,088.

Our invention relates to new and useful 1mprovements in boom feet for excavators.

Power-excavators, and more particularlypower-shovels, are well-known in the excavating art. They have a main platform, which contains most of the machinery. A boom, with its foot pivotedon a horizontal pivot to one edge of this platform, carries the excavating implements.

It is the principal object of our invention to provide, for such a machine, a more wearresisting boom-foot pivot, and one '"which will introduce less strains into the boom.

Further objects andadvantages of our invention will be readily evident, as the description progresses.

Theinvention consists in the novel parts, and in the combinations and arrangements thereof, which are defined in the appended claims; and of which one embodiment is exemplified in the accompanying drawings which are hereinafter particularly described and explained.

Throughout the description, the same reference number is'applied to the same member or to similar members.

Figure 1 is a horizontal section of part of the platform, with a plan view of the foot of the boom and boom braces. I

Figure 2 is a vertical section of the sam part of the platform, with a side elevation of the foot of the boom, all taken along the lines 22 of Figure 1, with the link removed. v

' Figure 3 is a plan View of one of the boom foot castings.

Figure 4 is a side elevation of said cast- Figure 5 isa plan view of one of the links which holds the boom foot in place.

- Figure 6 is a side elevation of said link.

Figure 7 is a horizontal section of part of the platform, showing one of the pins welded in place. I

Figure 8 is said part, partly in vertical section and partly in side elevation, showing the pin welded in place, all taken along the lines 88 of Figure 7.

Referring to the drawings, it will be seen that 10 is the main platform of an excavator.

Projecting forwardly therefrom are a pair of lugs 11, 12 to hold the right hand brace, a pair 13, 14 to support the right hand boom foot casting, a pair 15, 16 to support the left hand boom foot casting, and a pair 17, 18 to hold the-left hand brace. I

' The main structural part 19 of the boom, has riveted at its foot the two boom foot castings 20, 21, of each of which a reinforced curved portion 22 or 23, bears against a pin 24'or 25, which passes through the lugs 13 and 14 or 15 and 16, and is welded in place as at 26 or 27. The fact that this curved portion 22 or 23 does not completely embrace pin 24 or 25 we shall describe in the claims by the word open; Each boom foot casting also carries, integral therewith, reinforcing webs 48, and a hook 28 or 29, which engages a hold 30 or 31 in a link 32 or 33. Each such link has a hole 34' or 35, which fits over pin 24 or 25, and'is held in place by acotter-pin (not shown) passing through hole 36 or 37 of such pin 24 or 25. The object of the links is to limit the depar ture of the boom foot castings from contact with the pins 24 and 25. These pins are made of softer material than the lugs and the boom foot castings, and are readily replaceable, thus taking all the wear. One of the linksis shown in Figures 5 and 6, in which 38 represents a rounded portion of the edge of the hole 30, which has been rounded for engagement with the hook 28. 7 Passing through lugs 11 and 12 or 17 and 18, is a pin 39 or 40, which is welded in place, as at 41 or 42. Each such pin supports abrace- link 43 or 44, to which is attached one of the boom braces 45 and 46, adjustable as by turnbuckle 47. Each boom brace passes to an anchorge (not shown) on the side of the boom.

The reason that the pins 24, 25, 39 and 40 are all welded in place is to prevent the pin from rotating and thus grinding the boom foot casting and the lugs, more particularly the latter. Any slight wearing of the curved portions 22 and 23 of the boom foot castings, can be taken up by the turnbuckles, The weld on each of the pins extends only about one-third ofthe way around and is only about a quarter inch thick. To renew a pin, the weld would either be chipped away, or softened slightly by an acetylene torch, the pin being then knocked out.

In the past it has been usual to have rounded points at the foot of the boom stepped into sockets on the platform. Our invention is not a mere reversal of the parts of this former device, for the following reasons:

First, our invention causes the boom and the boom braces to rotate about the same axis, when the boom is raised or lowered, thus eliminating strains and slack in the braces.

Secondly, in machine shop practice, it is infinitely simpler to align the eight holes for the four pins, than to align pockets for seating the rounded ends of the two boom footcastings of the prior art. In either case, the two boom foot casting can be aligned, without chipping, by adjusting the template for the rivet-holes or bolt-holes (such as 49) to the pivot point of each casting as at A in Figure 2. Thus the holes in each casting are adjusted to the concave surface of that casting itself, thus rendering all boom foot castings interchangeable as well as automatically aligned to all others.

Thirdly, when the swing of the machine is accelerating or decelerating, the moment of inertia of the boom and all that is carried by it, tends to bend the boom to one side, thus pulling one of its feet out of engagement with the platform. Our construction permits this movement to a limited degree, thus introducing an element of flexibility int-o the boom foot mounting.

Fourthly, when the swing of the machine is accelerating or decelerating, the moment of inertia of the dipper and contents tends to rotate the outer end of the boom about the lengthwise axis of the boom, thus lifting up one foot of the boom and depressing the other. Our construction permits this movement to a limited degree, thus introducing a further element of flexibility into the boom foot mounting.

Fifthly, this same tendency to rotate the outer end of the boom about the lengthwise axis of the boom tends to bend one leg upward and the other leg downward about a point such as B in Figure 2. This causes a shear stress in the rivets or bolts which fasten the boom foot castings 20 and 21 to the main structural part 19 of the boom. This shear stress is proportional to the lever arm from B to A, which is the point of contact of the boom foot casting with its support on the main platform. Obviously our construction by reversing the sex of the contacting parts, decreases this lever arm n'iaterially.

The old construction possessed to some extent the third and fourth advantages above enumerated, but these are retained and augmented by our new construction. When the former boom was twisted, as aforementioned, the torsion was considerably reduced by one of the boom foot castings riding up and out from its socket. If we were to have drilled holes through our boom foot castings for the pivotal insertion of pins 24 and 25, we should have lost this advantage of the old design, and this loss would have greatly olfset the advantages gained by other features of our invention. But, by not completing the circle of curve 22 tightly about pin 24, and further by giving curve 22 a larger radius than that of the pin, we retain the riding up and out of the old construction, and in fact permit even more riding up and out. The double pivot feature of the links 32 and 33 permits this riding up and out, while at the same time limiting the departure of the boom foot from contact with the pins.

Having now described and illustrated one form of our invention, we wish it to be understood that our invention is not to be limited to the specific form or'arrangement of parts hereinbefore described, except in so far as such limitations are specified in the appended claims.

We claim:

1. In a power excavator, the combination of: a main platform, with four pairs of forwardly projecting lugs; aligned holes through all eight lugs; four cylindrical pins, one being inserted in each pair of holes, and each pin being removably welded in place; a boom; two boom-foot castings attached thereto, each having a rearwardly open projecting concave surface, of greater radius than that of the pin, for engagement with one of the aforementioned pins, each casting also having a forwardly projecting hook; two links, each engaging one of said hooks and one of said pins, for limiting the departure of said concave surface from contact with its pin; means for retaining each link on its pin; and sidewardly projecting adjustable boom-braces, each passing from the boom to one of the other two pins.

2. In a power excavator, the combination of: a main platform, with four pairs of forwardly projecting lugs; aligned holes through all eight lugs; four pins, one being inserted in each pair of holes; a boom; two boom-foot castings attached thereto, each having a rearwardly projecting concave surface, of greater radius than that of the pin, for engagement with one of the aforementioned pins, and each casting also having a forwardly projecting hook; two links, each engaging one of said hooks and one of said pins, for limiting the departure of said concave surface from contact with its pin; means for retaining each link on its pin; and sidewardly projecting boom-braces, each passing from the boom to one of the other two pins.

3. In a power excavator, the combination of: a main platform, with four pairs of forwardly projecting lugs; aligned holes through all eight lugs; four pins, one being inserted in each pair of holes; a boom; two boom-foot castings attached thereto, each having a rearwardly projecting open concave surface, of greater radius than that of the pin, for engagement with one of the aforementioned pins, means for limiting the departure of said concave surface from contact with its pin; and sidewardly projecting boom-braces, each passing from the boom to one of the other two pins.

4. In a power excavator, the combination of: a main platform, with four pairs of forwardly projecting lugs; aligned holes through all eight lugs; four pins, one being inserted in each pair of holes; a boom, having two laterally aligned rearwardly projecting concave surfaces, of greater radius than that of the pin, each of said surfaces being for engagement with one of the aforementioned pins; means for limiting the departure of each of said concave surfaces from contact with its pin; and sidewardly projecting boom-braces, each passing from the boom to one of the other two pins.

5. In a power excavator, the combination of: a main platform, with two convex forwardly upwardly projecting parts; a boom; two boom-foot castings rigidly attached thereto, each having a rearwardly projecting concave surface, of substantially greater radius than that of the convex part of the platform, for supporting engagement with one of the aforementioned convex parts of the platform; means closely associated therewith, for limiting the departure of said concave and convex parts from contact with each other; and sidewardly projecting boombraces, each passing from the boom to a pivotal anchorage on the platform, the axes of such anchorages being in alignment with the axis of pivot of the boom-foot.

6. In a power excavator, the combination of: a main platform, with two convex forwardly upwardly projecting parts; a boom, having two rearwardly projecting concave surfaces, of substantially greater radius than that of the convex parts of the platform, for supporting engagement with the aforementioned convex parts of the platform; means closely associated therewith, for retaining said concave and convex parts in engagement; and sidewardly projecting boom-braces, each passing from the boom to a pivotal anchorage on the platform, the axes of such anchorages beingin alignment with the axis of pivot of the boom foot.

7. In a boom-foot casting for excavators, the combination of: a flat plate; reinforcing webs rising from said plate; a forwardly projecting hook, on the outer surface of said plate, to engage a retaining link; and a rearwardly projecting reinforced concave surface, to engage supportingly a convex projection on the main platform of the machine; said plate being further characterized by containing holes for riveting or bolting to the boom proper, said holes being located by template with relation to the point of contact of said concave surface.

8. Boom foot securing means for excavators, comprising: two lugs, on the main frame of the excavator, having aligned holes; a pin, of less wear-resisting material than the herein-after-referred-to boom foot lug of the excavator, said pin passing through said holes, projecting slightly beyond one of said lugs, and directly removably secured to such. lug against rotation with respect thereto, while permitting free rotation of the boom foot about said pin; and a boom foot having a rearwardly projecting open lug characterized by a concave rearwardly pro ecting portion of greater diameter than said pin, for engagement therewith.

In testimony whereof we afiix our signatures.

WERNER LEHMAN. MITCHELL L. FYKSE.

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