US1886381A - Excavating machine - Google Patents

Description

Nov. 8, 1932. R ow 1,886,381

EXCAVATING MACHINE Filed Dec. 26. 1929 4 Sheets-Sheet 1 Z9 INVENTPR ATTORNEY Nam-8, 1932. R. R. DOWNlE EXCAVATING MACHINE Filed Dec. 26, 1929 4 Sheets-Sheet 2 &N

ATTO NEY INVENTOR RJfflmz/nze R. R. DOWNIE EXCAVATING MACHINE Filed Dec. 26, 1929 4 Sheets-Sheet- M W 1 h O Z 9 7 0 w 7 0 w J Nov. 8, 1932.

Patented Nov. 8, 1932 ROBERT REX DOWNIE F BEAVER FALLS, PENNSYLVANIA EXCAVATING MACHINE Application filed December 26, 1929. Serial No. 416,629.

This invention relates to improvements in excavating machines, especially those, excavating machines known as clamshells.

Among other objects, the invention aims to provide means for delivering a heavy thrust to the clamshell bucket during the taking of the load, so that excavating in hard earth and-even in rocky soil may be undertaken by a clamshell excavator.

Another object is to provide, in a machine of this character, means for preventing the upward pull of the bucket closing line from diminishing the engagement weight of the bucket.

A further object is the provision of a machine of this character having but two power members and no other channels of control for actuating and controlling the bucket and boom in all movements in the vertical plane of operation.

The invention has other objects which will appear from the following description.

Referring to the accompanying drawings, forming a part of this specification and showing the simplest form of the invention now known to me,

Fig. 1 is a side elevation of a machine embodying the invention, showing the boom, and bucket and control means therefor, but

only a portion of the handling machine;

Fig. 2 is an enlarged plan View showing the manner in which a single power actuated line actuates two bucket-closing lines through relay drums, the view being substantially on the line 2--2 of Fig.1;

Fig. 3 is an end elevation from the left end of Fig. 1 on an enlarged scale, the bucket, the handling machine and other distant parts being omitted;

Fig. 4 is an enlarged elevation showing the outer end of the boom and the parts carried thereby;

Fig. 5 is an enlarged sectional elevation of the details of construction shown in F 4;

Fig. 6 is a large scale elevation of the bucket, the View being from the same position as Fig. 1 except showing the bucket closed;

7 is a side elevation of the bucket of Fig. 6;

Fig. 8 is a section on the. line 88 of Fig. 4 but drawn to a still larger scale; and

Fig. 9 is a section on the line 99 of Fig. l, drawn on the same scale as Fig. 8. 1

Referring particularly to the drawings, there is shown the digging end only of a standard handling machine, whose construe tionforms no part of this invention and hence is not disclosed. In this instance, the handling machine illustrated is a standard non-revolving excavator; however, the handling machine may be of the type shown in my pending application, Serial N 0. 411,523, filed December 4:, 1929, or of the type disclosed in my pending application, Serial No. 298,501 filed August 9, 1928, or any other revolving excavating machine: The essen tial parts of any such a machine are a traction base, a frame mounted on the traction base, an engine carried by the frame, provision for horizontal swinging, at least two drums driven by the engine, and suitable control. means for starting, stopping and holding the rotary drums, a line or cable being wrapped around each drum and passing out to the boom and scoop.

Only two lines are employed to effect all excavating movements of the scoop and these two lines are under the constant control of the operator who operates the drums by means of two hand. levers. Side swinging of the boom, as for discharging of the spoil, is effected by a third drum controlled by a treadle, thus making it possible for the operator to maintain his complete controlv of the position of the scoop during side swing- I ing.

Herein, the handling machine of Fig. 1 includes a traction base 15, which is shown diagrammatically, a frame 16, a boom 17 pivoted to swing vertically, as at 18, and capable of swinging horizontally along with the vertical mast 19 which turns aboutthe vertical axis of pivot pins 20. A power actuated line 21 passes around the segmental grooved sheave 22 to which the hoisting line is attached by means of a yoke, so that rotation of the sheave is followed .by boom and mast.

In order to elevate and lower the boom, a hoisting line 23 is provided, said hoisting til line extending from the swing yoke 24 to and about a sheave 25 fixed near the outer end of the boom, and thence to guiding sheaves on the mast and machine and to the engine-driven drum (not shown). A. sheave stand 26 fixed at the outer end of the boom elevates the sheave 25 a considerable distance above the boom so as to obviate interference of the hoisting line 23 and other parts to be described. This sheave stand is so made as to be readilyremovable to permit the boom 17 to be used with other excavating devices, for example, a ditcher at-' tachment, as disclosed in my Patent No 1,511,114. :I

By means of the above described mechanism, the boom may be hoisted and lowered, being swingable through an angle of 136 or more in a. vertical plane and also being swingable through an angle 180 more or less in a horizontal plane. If the boom is mounted on the machine of my'pending ap plication, Serial No. 411,523, filed December 4, 1929, it will be capable or horizontal swinging in a total arc of 360.

Mounted upon the boom, in a manner to be described, is a. column chain consisting of a series of link elements, and constructed and arranged to transmit longitudinally any pressure or thrust imposed upon it; in othe words, capable of withstanding compression forces without buckling or. yielding. The clamshell bucket is carried at the lower end of the column chain and will be described hereinafter.

As is customary in clamshell buckets, the bucket is elevated by a continuation of the. same power application by which the jaws are closed. In this instance, there is a pair of bucket closing and elevating lines 27 (see Figs. 1, 2 and 3,) said lines passing around guiding sheaves 28 at the outer end of the boom and thence to respective relay drums 29, which are mounted on a common shaft with the drum 30, as shown at Fig. 2, the three drums being on the boom 17 near its outer end. A main bucket-controlling line 31 is wrapped around drum 30 and passes around guiding sheaves to the previously mentioned engine-driven drum by which the scoop or bucket is controlled.

By the described construction, when the line 31 is pulled in by the engine, the two lines 27 will close the bucket (it previously open) and then hoist the bucket together with the column chain.

Referring to Figs. 1, 6 and 7 the clamshell bucket or scoop has two jaws 32 which are pivot-ed as by a pivot pin 33 and whose digging edges are armed with excavating teeth 34. The lines 27 are connected with the pivot pin 33 in a manner to be described, and the jaws are so mounted that when the pivot pin is raised, the two jaws close. In order to effect closing of the jaws without an accompanying elevation of t 1e clamshell, provision is made for transmitting pressure from the boom through the medium or the column chain to the jaws, so that the teeth of said jaws are forced to bite into the earth or other material being excavated- To transmit such pressure to one of the jaws, a pair of arms 35 are provided, each secured at its upper end to a head-piece 36 which is attached to the lower end of the colui'nn chain, as will be described. The lower end of each arm 35 is pivoted to the jaw. The other jaw is connected by a pair of links 37 to the head-piece, each link being pivoted to both the head-piece and the jaw. It will be obvious that any pressure exerted upon the head-piece will be transmitted through the arms 35 and links 37 to the corresponding jaws of the scoop and will tend to force the teeth 34- downwardly when the jaws are wide open, as in Fig. 1. Furthermore, it will be evident that as long as this pressure is maintained, the closing or the jaws by means of the lines 27 will not effect any material elevation of the bucket.

In order to guide the bucket closing lines 27 to the sheaves 38, a yoke 39 is provided, said yoke being pivoted to the head-piece 36 for angular movement in the transverse vertical plane. The yoke 39 is pivoted as at 0 and carries a pair of upper rollers or sheaves 1-1 and a pair of lower rollers or sheaves 12, the two pairs of sheaves being at each end of the yoke and lying in planes at right angles to each other, as clearly shown in Fig. 7. Each line 27 passes between the two sets of rollers 11, and down around the cone sponding sheave v33, the two sheaves being mounted on a common axle carried by a yoke 13, passing around the main pivot pin of the clamshell. The yoke i3 is so formed and arranged that the reaches of the cables 27 between the sheaves 38 and the sheaves 28 at the end 01 the boom may normally lie straight, parallel with each other, and centered in the transverse vertical center plane ofthe scoop, and thus may be received upon sheaves 38 without side draft and without exerting a twisting force upon the scoop or upon the column chain which is attached to the scoop. The ends of lines 2'? are attached to the opposite ends of an equalizing bar 14, said equalizing bar being pivoted, as at (Fig. 6) to the head-piece 36.

It will beclear that the lines 27 work in two parts, while closing the aws of the scoop, and thereafter while hoisting it work in single part without any movement of the sheaves 38. The sides of the grooves of the sheaves or rollers and 42 lit the lines 17 fairly closely, but in the grooves of sheaves 38 allowance is made for a slight disalinemcnt of the sheaves, which occurs at certain intermediate points in the opening and closing movements of the scoop.

' the pivot pins 47 Referring to Figs. 3, 4 and 8, the previously mentioned column chain is shown as comprising, in this instance, two double link sprocket chains including links 46 and pivot pins 47. The two sprocket chains are parallel and identical in all respects and their opposed inner links are connected by \l-shaped yokes 48 operatively integral with said links, and having integral spacer blocks 49. The spacer blocks 49 with the yokes 48 provide generally T-shaped spacing members which are normally separated a small fraction of an inch,

but which abut against each other as soon as any compression stresses are imposed upon the column chain. WVhcn this occurs, the column chain will assume a very slightly bowed shape, as shown in Fig. 1; and when in this condition, the column chain may transmit a very heavy thrust to the clamshell bucket.

It will be clear that the chain links 46, together .with their pivots 4?, permit the column chain to support a load under tension, that is, the load arising from the attachment of the clamshell to the lower end of the column chain and from any excavated material which may be within the bucket. The spacer blocks 49 sustain a compression or column load, as for example, when the boom hoist line is slackened and the effective portion of the weight of the boom is supported by the column chain. See Fig. 1.

As indicated in Fig. 7, the lowermost links of the column chain are pivotally connected to ears 5O projecting above the yoke 39. Thus the scoop has two horizontal axes of movement with reference to the column chain, the one longitudinal and the other transverse; and movement may occur about either axis independently of movement about the other; thus there is provision for universal movement of the scoop relative to the column chain. The objects of this construction are, first, to permit the scoop to accommodate itself freely to the face of the work,

- and second, to avoid eccentric loading and possible binding of the chain, which binding might interfere with the column setting of the chain, as will be understood by referring to Fig. 1.

The column chain, in the illustrative embodiment, is carried by the boom in such a Way that the unused length thereof is stored upon the boom.v It will be clear that the chain is flexible in one direction because of and hence the chain may be, and preferably is, passed around a pair of sprockets 51 suitably designed for engagement with the pivots 47, said sprockets 51 being mounted on a shaft 52, which is carried by a bracket 53 depending from the outer end of the boom and providing a housing for the sprockets and for a brake drum 54 and associated parts, by means of which the sprockets are secured against rotation, thereby to prevent travel of the chain on or 0H the boom (see Fig. 4). VVhile only one brakev drum is shown in Fig. 3, if desired, two

be prevented. The brake lever 57 is guided by a curved guide 58 secured to the boom and has an adjustable connection with a link 59, which is pivotally connected thereto and also to an arm 60 connected with the hub 61' of sheave 25. The arm 60 has a pivoted cap,

or hub connection 62, which by means of the spring 62, lightly grips the hub 61, the

pressure of said spring being adjustable, as-

indicated. As the cap 62 lightly grips the hub 61, arm 60 tends to rotate with the sheave 25 when the boom hoist line is pulled in or let out. However, arm 60 is permitted to oscillate only through a small are, there being a pair of stops 63 projecting from the sheave stand 26 (Fig. 8), to limit the movement of the arm to an arc of about 90.

From the foregoing, it will appear that when the boom hoisting line 23 is pulled in by the power actuated drum to hoist the boom, the sheave 25 will be rotated in a counterclockwise direction and will tend to move the arm 60 in the same direction, but said arm will be stopped by the righthand stop 63 of Fig. 4. When the line 23 is slackened to permit the boom to descend, the sheave 25 will be rotated in a clockwise direction and the arm 60 will quickly move to the dotted line position of Fig. 4, where it will be stopped by the lefthand stop 63. In the dotted line position, the arm 60, in conjunction with the adjustable link 59, provides a toggle lock for the brake lever 57, so that the brake is set in this position of the parts. When the brake is set, the sprockets 51 cannot rotate and the column chain can neither rise nor descend but must set as a column when a compression load is imposed upon it.

As shown in Fig. 5, the adjustable link 59 is in two parts and is made so as to be nonresilient under tension (as in releasing the brake 54), but yields to a certain compress sive force determined by the resistance of a compression spring 64 carried by the link. Secured to one of the parts of link 59 is a sleeve 65 screw-threaded at one end, as shown, and having a longitudinal slot 66 receiving a pin 67, which is fixed to and projects radially from the other part of the link 59. The compression spring 64 is interposed between a shoulder piece 68 (fixed to the same part of the link which carries the sprockets may 7 in its movement in the reverse direction upon v gers supporting the rails so as pin 67) and one or more tension adjusting nuts 69 on the threaded end of sleeve 65. fhe compressive resilience of the link 59 permits the am 60 and the link to have a toggle action at the brake-setting end of travel of the arm 60, which serves to hold the arm 60 and the brake lever 57 against casual releasing movement. Furthermore, the resilience of link 59 serves, to some extent, as an auto matictake-up for wear of the brake band 55. It will also be clear that the operator, by controlling the hoist line 28 in the usual manner, 'may obtain perfect control over movements, of the column chain, without the necessity for the manipulation of an additional lever or power element. 1

While the boom itself could be made of such length and of such proportions as completely to enclose and receive the entire length of the column chain, in this instance I have shown an arrangement of parts now preferred by me, whereby the column chain is stored on a rack mounted on the underside of the boom.

Referring to Figs. 4, 8 and 9, and first to Fig. 8, the boom 1'? has secured thereto a plate 70, with angles 71 at the corners for supporting the brackets 53. Secured to the brackets 58, and extending between them, is a cross piece 72 providing a support for pairs of U-shaped clips 73, to which are welded spaced rails 74. The space between the rails 74 exceeds the diameter of the pivot pins 47 of the sprocket chains, and said pivot pins are slidable along the rails 7% with the links of the chains both inside and outside of the two rails between which the pivot pins pass.

1 1e rails 74 are spaced a sufficient distance below the boom 17 to provide clearance for the yokes 48 and the spacer blocks 49, the rails 74 extending practically the entire length of the boom, as shown in l, and may be curved, as at 75, near the pivoted end of the boom, so as to permit the column chain to move around the tracks and forwardly on a second tier of the rack, when the chain is elevated. At intervals, hangers 76 are provided, as best shown in Fig. 9, said hanto be spaced apart from each other and yet rigidly secured upon the boom.

If desired, instead of the rails being curved at the point l5, a roller or a pair of idler be provided to assist the chain the lower tier of the rack. W hen the clamshell bucket is in its uppermost position, and practically the entire length of the column chain is stored upon the rack, provision is made for stopping the upward movement of the chain by stop pieces 7'? 6 and 7) which are fixed to the two sets of links next to the lowermost links otthe chain. These stop pieces or blocks are suitably shaped to contact atone side with the edges oi the rected finger 81 for contacting with the low-' ermost spacer block 49. Thusthe counterweight 7 9 tends to throw the column into the slightly bowed position of Fig. l'as' soon' as the column chain is relieved of any partof the weight of the bucket, as when the bucket encounters the material to be excavated.

The operation Assuming the machine to be in the position of 1, the closing line 31 is wound in by power, thus pulling in lines 27 and closing the jaws of tie clamshell so that the load is gathered by the jaws. During this operati 1, the efi'ective per vion ot the weight of the mini is allowed to bear upon the clamshell durin that-is, during the downward and raking movements of the teeth. However, the hoisting line maybe pulled in to elevate the boom slightly and to relieve the pressure on the column chan during the final stage of the bucket closing movement. The sheave 25 is rotated sufiiciently by this preliminary hoisting movement of cable 23 to swing the friction arm 60 out or" the brake-applying position, so as to release the brake 54.

By the above method of operation, the inwinding or cable 31 and its extensions 27 may be continued from the scoop closing stage into the scoop hoisting stage, without interruption. However, as an alternative method, the inwinding of the closing line 31 may be suspended'as soon as the scoop is closed and the hoisting line 23 may then be wound in suficiently to revolve sheave 25 and thus release the brake and the inwinding of line 31 may then be resumed.

The possibility of unintentional continued winding of the closing line, after closing has been completed and before the brake has een released, is provided for by proper adjustment of the length of link 59 and the pressure of spring 62 (Fig. l). These are so adjusted that when the arm is in its brakesetting position, the brake will be applied with little more than suliicient force to sup port that portion of boom weight which may be delivered upon the chain and to provide the necessary reaction to the normal digging pull of cables 27. Thus, inthe event that the line 31 is wound in after the scoop is closed, against the resistance of the said brake, the chain will be subjected only to little more than its normal load and the overload willthe period of greatest effectiveness,

cause the brake to slip until released. All of these parts are designed to be strong enough to withstand the full power of the lines, so that no breakage of parts, but only waste of power, can result from operating errors.

As the scoop is orawn up by means of cables 27, the links of the column chain are deflected by the guides 78 into the raclr. Hoisting by means of cable 23 may be star ed at any convenient time. Elevation of the boom from the horizontal position of 1 (which is the preferred position for digging because it is the position inwhic the boom. weight is most eiiective), shortens the working radius or horizontal distance from the vertical center line of the load to the swinging axis of the machine; and if there are cross braces or bulk-heads in the trencl with which the scoop would interfere, if its working radius were shortened during hoisting, then the boom hoisting is postponed until after the scoop has. risen clear of the obstructions. Then the scoop is held shut by cables 27 and the boom and scoop are hoisted to a suitable height by cable 23 and the boom is swung about to the point of discharge. At this time, thehub of sheave 25 slips relative to the friction arm 60, the arm remaining against the right-hand stop, l. When the scoop has been stopped for discharge, the boom is lowered sufficiently to revolve sheave 25, and arm 60 in a clockwise direction, so as to set the brake 54-. Then the closing line 31 is slacked oil and the weight of the scoop and load are carried by the column chain, then under tension, and the scoop opens to discharge the load. The boom is. then swung back to and lowered over the work, with the open scoop supported by the column chain, with the hub of sheave 25 slipping relative to the arm 60 during the boom lowering operation.

There are alternative methods of lowering the scoop to the floor of the excavation. After the boom has been lowered to the approximate position desired for the loading operation, the boom may be raised suiiiciently 1 artially to release the brake 5% so that the open scoop will descend, supported or checked by the column chain tension, and under the control of the hoisting cable 23 through the medium of the sheave 25 and brake 54, until the scoop strikes the material.

Instead of this operation, the closing line 31 may be drawn in, closing and taking the weight of the scoop, and the hoisting cable would then be drawn in suiliciently fully to release the brake 54-, inci-c cntally raising the boom slightly, and the scoop may then be lowered under control of line 31. By this last method, when the scoop approaches to a point within two or three eet of the floor of the excavation, the hois no; line is released a little so as to setthe brake and transfer the weight of the scoop onto the chain, and the closing line is then freely released to permit the scoop to open, just clearing the material.

The boom is nowlowered, permitting the scoop to rest upon the material, as in Fig. 1.

With continued lowering of the boom and relieving of; the tension on the column chaln,

comes effective, and the counterweight lifts the lowermost spacer block until it comesinto contact with the spacer block adjacent to and above it. Each spacer block in turn tends to come in contact'with the spacer block above, and the final result is that the chain assumes slightly bowed shape, which is maintained by pressure of the boom weight, When the chain isin the position of Fig. 1, the spacer blocks are carrying a compression load throughout the entire length of the chain from the end of the boom downwardly to the ucket, while the links proper carry compression over certain portions of the length of thechain and carry tension in the remaining portion of the chain.

While it is preferred to employ a simple weighted arm for setting the chain, that is, for putting the chain in such position that it cannot be collapsed by'boom weight or its equivalent, alternative mechanisms, within the scope of the broader claims, may be used. F or instance, tension springs may be employed extending from each link to the next along a line intermediate between the pitch line of the chain proper and the center line of the series of spacer blocks, the springs having sufficient initial tension to pull the unrestrained chain into a slightly bowed position, as in Fig. 1, but yielding to permit the chain to pass over the sprockets at the end of the boom. g

As anothermeans for setting the chain, 1 may employ an arm pivotally attached to the boom near the outer end thereof and depending from the boom and carrying an idler sprocket at its lower end, the idler sprocket pressing against the standing part of the chain so as to bow the chain in the proper direction to take a column load. The idler sprocket should be yieldingly pressed against the chain, either by a spring or by a weight, so as to cause pressure to be exerted by the idler against the column chain. The more fully described counterweighted arm is preferred, because of its simplicity and inexpensiveness and because the counterweighted arm does not lessen the clearance height of the scoop.

From the above, it will be clear that the described machine provides means permitting the delivery of boom weight upon the scoop during the taking of theload to increase the engagement force and thus to permit penetrating and digging harder material with a givenweight of'scoop having a given length of cutting edge than is possible with a scoop not maintained or backed by external force. Thus, it is possible, with the present invention, to make a clamshell bucket dig materials of a hardness heretofore considered prohibiting the use of such buckets.

The described machine is also advantageous in that the upward tilting of the closing line does not lessen the ground-engagement weight of the scoop. The excavating machine of this invention also has a more rapid bucket closing action with a given closing force than is obtainable in a clamshell having only cable connection with the boom.

The usual working position of the boom will be horizontal, as in Fig. 1, and in this position the-maximum weight may be imposed upon the bucket during diggin As the column chain descends, more and more of its weight is eliective for increasing the penetration of the teeth. When the column chain is largely carried by the boom, the weight of the'boom will necessarily be increased and this increased weight is, of course, effective, when the column chain is set, to cause the bucket to bite into the material. However, as the boom is pivoted, only about one-half of its total weight, including the weight of the carried chain, may be imposed upon the vertical length of the column chain. As the column chain moves ofi' the boom, the compressioncolumn increases in length and hence inweight, and thus becomes increasingly effective to force the bucket down through very hardmaterial.

The machine is so constructed as to make unnecessary the use of one or more poles or other hold-down means attached to the scoop and made vertically slidable at the end of the boom for scoop hoisting. Such hold-down devices are very unwieldy when side-swung in hoisted position, and in city work are certain to interfere with trees, overhead wires, and the like.

Obviously, the present invention is not restricted to the particular embodiment thereof herein shown and described. Moreover, it is not indispensable that all the features of. the invention be used conjointly, since they may be employed advantageously in various combinations and sub-combinations.

What I claim is 1. In an excavating machine, the combination of a pivoted boom; a vertically-digging bucket carried thereby; a line for hoisting the boom; and an articulated pressuretransmitting column member connecting the boom and bucket and depending from the end of the boom when the bucket is in digging position; the column member being sufficiently flexible because of the articulations to be movable into a position wherein it is generally parallel to the longitudinal axis of the boom; and power-actuated means to move the column member longitudinally.

2. In an excavating machine, the combination 01" a pivoted boom; an opposed action bucket carried thereby; a line for hoisting the boom; a line for hois ing the bucket; and a longitudinally movable, pressure-transmitting column extending vertically downwardly from the boom to the bucket and connected at its lower end to the bucket, said column being articulated at numerous points intermediate of its points of attachment to tl c boo-m and bucket so as to assume the flexibility of a chain, when bent in one direction; said column having means to prevent bending thereof in the opposite direction.

3. In an excavating machine, the combination of a pivoted boom; a clamshell bucket; a power-actuated line for swinging the boom in vertical planes; a power-actuated line for closing and hoisting the bucket; a linked member depending from the boom and connecting the boom and bucket, the links of said linked member contacting with each other, when the linked member is subjected to compression, so as to permit the transmission of heavy thrusts longitudinally of the linked member, when substantially vertical;

said linked member being longitudinally movable by the bucket-hoisting line.

4. In an excavating machine, the combination of a pivoted boom; a clamshell bucket carried thereby; a line for hoisting the boom; winding means for closing and hoisting the bucket a linked member connecting the boom 1 and bucket; and a sprocket carried by the boom and supporting and guiding said linked member; the links of said member being so constructed and arranged as to allow the linked member to turn about said sprocket but preventing more than slight relative disalignment of the links in the direction opposite to the one in which the links turn when passing over said sprocket.

5. In an excavating machine, the combination of a pivoted boom; a clamshell bucket carried thereby; a boom-hoisting line; a sheave upon the boom about which said line passes; winding means for closing and hoisting the bucket; a column-chain connecting the boom and bucket; a holding-sprocket carried by the boom and engaging said column chain; and means operatively connecting said sheave and said sprocket whereby rotation of said sheave in opposite directions may be employed to hold and release said sprocket.

6. In an excavating machine, the combination of a pivoted boom; a clamshell bucket carried thereby; a V boom hoisting line; a sheave upon the boom about which said line passes; winding means for closing and hoisting the bucket; a column-chain connecting the boom and bucket; a holding-sprocket carried by the boom and engaging said columnchain; and control means connecting said sheave and said sprocket, said control means brake band, a brake lever, a link connecting the brake lever with the arm, and a brake drum; said brake drum being operatively integral with said sprocket.

7. In excavating machine, the combination of a pivoted boom; a ciamshell bucket carried thereby; boom hoisting line; a sheave upon the boom about which said line passes; winding means for closing and hoisting the bucket; a column-chain connecting the boom and bucket; holding-sprocket carried by the boom and engaging said columnchain; and control means connecting said sheave and said sprocket, said control means comprising an arm actuated by said sheave, a brake band, a brake lever, a link connecting the brake lever with the arm, and a brake drum; said brake drum being operatively integral with said sprocket; and the link being non-resilient under tension but yielding to a limited extent to compression, permitting the arm and link to have a toggle action at the brake-setting end of travel of the arm,

serving to hold the arm and lever against accidental releasing movement.

8. In an excavating machine, the combination of a pivoted boom; a clamshell bucket carried thereby; a boom hoisting line; a sheave upon the boom about which said line passes; winding means for closing and hoisting the bucket; a column-chain connecting the boom and bucket; a holdingsprocket carried by the boom and engaging said columnchain; and control means connecting said sheave and said sprocket, said control means comprising an arm actuated by said sheave, a brake band, a brake lever, a link connecting the brake lever with the arm, and a brake drum; said brake drum being operatively integral with said sprocket; and stops for limiting movement of said sheave-actuated arm so that the'arm and the link may form a tog gle to hold the brake lever in brake-setting position.

9. In an excavating machine, the combination of a pivoted boom; a clamshell bucket carried thereby; a boom hoisting line; a sheave upon the boom about which said line passes; winding means for closing and hoisting the bucket; a column-chain connecting the boom and bucket; a holding-sprocket carried by the boom and engaging said columnchain; and control means connecting said sheave and said sprocket, said control means comprising an arm actuated by said sheave, a brake band,a brake lever, a link connecting the brake lever with the arm, and a brake drum; said brake drum being operativ-ely integral with said sprocket; stops for limiting movement of said sheave-actuated arm so that the arm an d the link may form atoggle to hold the brake lever in brake-setting position; and the link being non-resilient under tension but yielding to a limited extent to compression,

serving to hold the arm and lever against accidental releasing movement.

'10. In an excavating machine, the combination of a pivoted boom; a. clamshell bucket carried thereby; a boom hoisting line; a

sheave u on the boom about which said line passes; winding means for closing and hoisting the bucket; a column-chain connecting the boom and bucket; a holding-sprocket carried by the boom and engaging said 001- umn-chain; and control means connecting said sheave and said sprocket, said control means comprising an arm having a frictional connection with the sheave, a pair of stops for limiting movement of the arm so that the arm moves through an arc while frictionally clutched to thesheave, and then encounters 1 one of the stops and ceases swinging, the frictional connection yielding to permit free continned I'OtEItIOII' of the sheave; said'control 1 means also comprising a brake connected to the sprocket to hold the sprocket a ainst ro- L .l. O

tation and mechanism connecting'the brake and the arm, said mechanism locking the brake agalnst accidental releasing, when the arm abuts one of the steps, but releasing the brakewhen the arm is near the other stop.

11. An excavating machine comprising, in

combination, a pivoted boom; a member flexible in one direction; a sprocketat the outer end of the boom over which the flexible member may move; and storage means fast to the boom for receiving and holding substantial.- ly the entire flexible member so as to be supported by the boom."

12. An excavating machine comprising, in combination, boom; a-fiexible' member which is substantially non-deformable by longitudinal compression; and a rack carried by the boom and havin a plurality of tiers connected together to provide a continuous tracker guide tor storing substantially the entire flexible member on the boom.

13. An excavatin'gmachine comprising, in

combination, a pivoted boom; a clamshell bucket; means for raising and lowering the boom; and alinked member carried by the boom and attached to the bucket, said linked member being substantially non-deformable by longitudinal compression, so as to be capable of transmittlng boom Weight to the bucket durin QXCttVittlOIl' means carrled b the boom for holding the linked member against longitudinal movement; and a rack attached to the boom and extending along the underside of the boom, said rack having a plurality of tiers connected together to provide a'continuous track or guide, so that the linked member moves to the next tier when the first tier holds its portion of the linked member, the rack thereby, providing storage for substantially the entire linked member,

or as much thereof as is not'in use.

let. An excavating machine comprising, 1n

thereof and to elevate the bucket with its jaws held closed; a pivoted boom; a second line for elevating and lowering the boom; a linked member connected to the bucket and carried by the boom and constructed and arranged to transmit compression forces longitudinally; and means for causing said linked member to automatically assume a slightly bowed shape when a compression force is imposed upon it.

15. An excavating machine comprising in combination, a bucket having jaws; a line connected to the bucket to close the jaws thereof and to elevate the bucket with its jaws held closed; a. pivoted boom; a second line for elevating and lowering the boom; a linked member connected to the bucket and carried by the boom and constructed and arranged to transmit compression forces longitudinally; and a weighted arm at the lower end of said linked member, but above the bucket, bearing against the linked member to make it assume a slightly bowed shape when a compression force is imposed upon it.

16. An excavating machine comprising, in combination, a pivoted boom; a clamshell bucket; means for raising and lowering the boom; a linked member depending from the boom and attached to the bucket, said linked member being substantially non-deformable by longitudinal compression, so as to be capable of transmitting boom weight to the bucket during excavation; and means carried by the boom to provide a continuous track for storing substantially the entire linked member on the boom.

17. An excavating machine comprising, in combination, a bucket; a boom; means connecting the bucket with the boom comprising a linked member spending from and movable relative to the boom; said linked member transmitting compression forces when vertical; means carried by the boom for temporarily holding the linked member from moving relative to the boom; an operatorcontrolled mechanism for controlling said holding means; and means on the boom for storing the linked member.

18. An excavating machine comprising, in combination, a bucket; a pivoted boom; a power driven line for raising and lowering the boom; a linked member carried by and movable relative to the boom and connected to the bucket; means carried by the boom for temporarily holding the linked member from moving relative to the boom; and mechanism actuated by said boom line for controlling said holding means.

19. An excavating machine comprising, in combination, a pivoted, rigid boom; operating mechanism therefor; a linked member carried upon the boom and transmitting compression forces longitudinally without collapsing; means on the boom for storing the linked member; a bucket having jaws carried by said linked member; and a power-actuated line for closing the j aws of the bucket; said line being so connected that it lifts'the bucket.

and moves the linked member longitudinally back upon the storing means, after the bucket jaws are closed.

20. An excavating machine comprising, in

combination, a bucket having jaws; a power line connected to the bucket to close the jaws thereof and to elevate the bucket with its jaws held closed; a pivoted boom; a second power line for elevating and lowering the boom; a linked member connected to the bucket and carried by the boom and con structed and arranged to transmit compression forces longitudinally; and means on the boom for storing said linked member when the bucket is elevated to jacent the boom.

21. An excavating machine comprising, in combination, a bucket having jaws; a line connected to the bucket to close the jaws thereof and to elevate the bucket with its.

a point adjaws held closed; a pivoted boom; a second jaws held closed; a pivoted boom; a second line for elevating and lowering the boom; a linked member connected to the bucket and constructed and arranged to transmit compression forces longitudinally; a sprocket on the outer end of the boom for engagement with said linked member; a brake for governing rotation of the sprocket; brake controlling mechanism operated by the boom elevating line; and means on the boom for storing said linked member when the bucket is elevated to a point adjacent the boom.

23. An excavating machine comprising, in combination, a clamshell bucket; a pivoted boom; a boom-supported member for holding the bucket; a power driven drum on the boom; a pair of drums on the shaft of the power drum; a line wound up by each of said drums; a pair of sheaves for said lines at the outer end of the boom; a pairof sheaves for said lines on the bucket; the lines being rigged to close the bucket and elevate it; and means for guiding the lines.

24. A column chain for transmitting compression forces to clamshells and the like comprising, in combination, a pair of parallel sprocket chains;yokes operativelyintegral with the pairs of oppose l inner links of the chains and extending inplanes substantially at right anglesto' the longitudinal axes of the chains, but on one side of .the chains; and a plurality of spacer blocks integral with the several yokes; adjacent ones of said spacer blocks touching each other to prevent any substantial deflection "of the column chain in one direction.

'25. A column chain for transi'nitting'compression forces to clamshells and the like comprising, in combination, a pair of parallel sprocket chains; yokes integral 'witlrthe pairs of opposed inner links of the chains and extending in planes substantially at right angles to the longitudinal axes of the chains, but on one side of the two chains; and a plurality of spacer blocks integral with the several yokes; each yoke andspacer block providing a T-shaped extension of each opposed pair of links, the ends of the heads of the T-shaped extensions being substantially abutted when the column chain hangs pendently, so that bending of the column chain in one direction is permitted to a very slight degree and is positively limited. Y 26; A column chain for excavating machines and the like comprising, in combination, a linked structure including a multiplicity of links which may turn relative to each other in one direction; means on the links preventing any substantial turning ofthe links but permitting a very slight disalinement in the opposite direction theaforesaid means, and the disalined positions of the links relative to each other, preventing collapsing of the chain under compression forces imposed longitudinally of the chain.

27, A column chain for excavating machines and the like comprising, in combination, a linked structure including a multiplicity of links which may turn relative to each other in one direction; means on each link adapted to abutlike means onthe two adj acent links to prevent any substantial turning of the links in the opposite direction; said abutting means being very slightly spaced apart when the chain is straight, so that when compression forces are imposed on the chain longitudinally, the small spaces between the said abutting means are taken up, and the chain assumes a slightly arcuate shape. v

28. A column chain for excavating machines and the like comprising, in combination, a multiplicity of pin-connected links which may turn freely in one direction; stop means on certain of the links for permitting a. only very limited turning of the links in the opposite direction in the same plane; and means to cause the chain to assume a slightly bowed shape, the chain bending until said stop means prevent further movement.

29. A columnchain for excavating maadjacent links to preventeny substantial chines and the like comprising, in combination," a multiplicity of 'pivota'llyconnected links which may freely turn in one direction stop means on, Certain of the links for'permittingonly very limited turning of the links in the opposite direction infthe same plane; and 'a' weighted arm on the lower end; ofthe chain and tending to turnthe chain in the direction which movement is limited by said stop means, so that said chain becomes slightly bowed assocn as pa'rt'of itsw'eig 'h t" is supported on the floor of the excavation.

30. A column chain for excavating ma chines and the like comprising, in combination, a linked structure including a multiplicity of links which may turn relative to eachother in one direction; means on each link adapted to abut like means on thetwoturning of the links in the vopposite direc tion; said abutting means being very slightly spaced apart'when the chain is straight; and

a counterweighted arm extending transversely of the chainand secured at an intermediate point to the lowest links of'the chain and bearing against the abutting means of the next higher link, so that when compression stresses are imposed on the chain longitudinally, the small spaces between the said abutting means are closed, and the chain assumes a slightly arcuate shape.

31. A column chain for excavating machines and the like comprising, in combination, a multiplicity of pivotally connected links which mayturn in one direction in the 100 plane of the chain; said links'carrying a, load, under tension; and means on certain of the links'for supporting a compression load; said means preventing the turning of the links in the opposite direction and in the 0 aforesaid plane, butpermittinga slight disalinement of the links so that the chain, when subjected to acompression load, assumes a slightly arcuate shape, being bowed in the aforesaid oppositedirection. v 32A column chain for excavating machines comprising a pair of parallel sprocket chains; yokes connecting opposed links of said chains; and means secured to the yokes and spaced fromthe'link pivots in a direc- 1 t'ion lateral relative to the chain,-said'means projecting longitudinally of the chain so as nearly to'abut each other, and contacting with each other to make a compression-sustaining column of the chain, when the chain 120'v is subjected to compression longitudinally. 33. A column chain for excavating machines c'omprisinga pair of parallel sprocket chains; T-shaped spacer blocks rigidly secured to the OppOsed l-inksof said chains 2 and extending all in the same direction laterally of thechain, with the beads of each'T extendinglongitudinally .of the'ch'ain and almost in contact with adjacent spacer blocks, above and below, when the chain is. pendant, 3

so that the chain may buckle slightly when a longitudinal thrust is imposed on it from the upper end and then may transmitvery heavy compression stresses longitudinally.

' '34. An excavating machine comprising, in combination, a boom; a columnchain having pivoted links; and means on the boom for storing said column chain; said chain-storing 1 means comprising a racksecured to and extending 'along'the boom on theunder side,said rack having two spaced longitudinal bars on each side, the pivots of the chain passing through the space between the bars on each side and the links ofthe chain being on both sides of said bars and preventing substantial lateral movementof the chain on the rack; said chain being movable longitudinally of the rack by a thrust orpull longitudinally of the chain.

35. An excavating machine comprising, in

' combination, a boom; a column chain; a

power-actuated boom-hoisting line; means carried on the boom for storing the column a chain; and 'means carried on the boom for preventing movement of the column chain relative to the boom said last-named means being actuated by power derived from the boom hoisting line.

36. An excavating machine comprising, in combination, a boom; a column chain supported by the boom; a power-actuated boomhoisting line; means for preventing movement of the column chain relative to the j boom; and mechanism actuated by the boomhoisting line for operating said means to hold and release the column chain.

, 3' 7. An excavating machine comprising, in combination, a boom; a column chain supported by the boom and movable from a posi-. 40

' ed means for swinging the boom in a vertical plane; a chain carried by'the boom and constructed and arranged to withstand heavy compression stresses imposed longitudinally; said chain being composed of a multiplicity of heavy links so that the chain adds greatly to the weight of the boom; a vertically digging bucket on the outer end of the chain; means for elevating and lowering the bucket yielding 001m whose weight uniformly a;

creases with its length thereby to impose an effectively heavier thrust on the bucket as the column chain descends from the support afforded by the boom;

39; An excavating machine comprising, in combination, a clamshell bucket, a single power a'ctuatedline to close and to elevate said bucket; a pivoted boom; a power-aw tuated line to swing said boom vertically; means supported by and releasably secured to the boom to transmit part of the boom weight compressively to the clamshell bucket; and means controlled by the boom swinging line to release said boom-supported means to permit movement thereof with the bucket. v I i 40. An excavating machine comprising, in combination, a pivoted boom; a clamshell bucket; linked means transmitting compression from the boomto the bucket; means on the boom for locking the linked means against horizontal movement; and two independently controlled, power-actuated lines, one being connected and arranged for closing, elevating and lowering the clamshell bucket, the other being connected and arranged for elevating and lowering the boom and being engageable with said looking means for controlling lockingand releasing of said compression-transmitting linked means.

41. A clamshell excavator comprising, in combination, a pivoted boom; a clamshell bucket; means on the free end of theboom to impose part of the weight of the boom on the bucket; and two independently controlled power-actuated lines, one being connected and arranged so as to control closing of the bucket, elevation thereof, opening of thebucket and lowering thereof, the other line being connected and arranged to elevate and lower the boom; and operator-controlled means to lock and release the means on the end of the boom. 7

In testimony that I claim the foregoing as my own, I have hereto affixed my signa-- ture.

ROBERT REX DOWNIE.

and chain; and means on the boom for storing the chain; the parts being so constructed and arranged that the boom carries the entire unused part of the chain,-thereby increasing its weight and making the total weight effective to bearagainst the bucket 5 to aid in digging hard material"; thechain,

as it moves ofi the boom, forming an un-

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