US2072012A - Dredging apparatus - Google Patents

Description

Feb. 23, 1937. c, SANDERS 2,072,012

DREDGING APPARATUS Filed May 6, 1935 2 Sheets-Sheet l Feb. 23, 1937. c. SANDERS DREDGING APPARATUS Filed May 6, 1955 2 Sheets-Sheet 2 gwucnfoc CfiarZes SanJar Patented Feb. 23, 1937 UNITED STATES PATE OFFICE DREDGING APPARATUS Charles Sanders, North Vancouver, British Columbia, Canada 2 Claims.

This invention relates to a new method of dredging operations by use of a bucket and drag-line in combination with an inclined runway which simplifies the equipment and provides a greater degree of efliciency over ordinary drag-line dredging operations.

My invention considerably simplifies the handling of the dredging equipment and lessens the cost of the same, especially the power equipment, such as used in continuous bucket line dredges or in ordinary drag-line dredging equipment, as it dispenses with the use of one winding drum and cable used as haul-back to position the bucket at the commencement of each digging or dredging operation.

My invention is more specifically designed. for gold dredging operations and a particular object is to provide economical and effective dredging equipment at a reasonable cost and of a kind that can be readily transported and erected at the site of operations.

My method of carrying out dredging operations differs from those effected by the bucket line dredge or the ordinary drag-line scraper mode of operations, and to the end that a proper understanding may be had of the difierence of the mode of operations as carried on by the aforesaid methods and by the use of my invention it is deemed advisable that a short description of the same be made with a view of establishing distinctive characteristics of each. I

In the ordinary bucket line dredge as used in gold dredging operations, the equipment is both heavy, powerful and costly.

The digging equipment consists of a digging ladder and a continuous line of buckets that travel at a slow speed around the same and powerful operative machinery.

The digging ladder varies in size and length in accordance with the depth to be dug and size of equipment of the dredge generally, but must be built sufiiciently strong to carry the enormous weight and strain of the buckets in operation, as the string of buckets must be long enough to reach the bedrock of the field plus the height from the surface to the top of the tumbler on the dredge where the bucket discharges its load.

The buckets must be of the most rugged construction as they often encounter huge boulders embedded in the gravels being dredged; therefore both buckets and ladder and operative mechanism must be of powerful and heavy construction, hence costly.

The process of digging is by rotating the bucket line around the ladder, practically only one bucket digs at a time. It descends the ladder empty and upside down, and upon reaching the bottom commences to dig until it reaches the turn in the ladder which is set at an angle consistent with the depth being dug, when it is lifted off the gravel 1 bed to commence its upward journey to discharge its load as it turns over the tumbler at the top of the ladder.

This operation is continuous while the dredge is working. Any variation of the depth of digging or dredging operations is eifected by lowering or raising the digging ladder by powerful lifting tackle requiring careful and skilful handling.

The buckets, by reason of their inclination upon the ladder after digging, can only carry approximately fifty per cent of their designed capacity.

The movement of the dredge is effected by the use of guy lines attached to deadmen, and in the case of large machines by the use of spuds.

A continuous bucket type dredge is limited in digging depth by the length of its ladder and on this account often has to pass over deep, rich bearing gravels to reach shallow and poorer fields by reason of not being able to reach the deeper and richer ones.

The drag-line scraper as a machine for moving gravel is possibly one of the finest that has been designed, but its very efiiciency condemns it as a means for saving gold as it digs downward and moves an immense amount of gravel that it does not pick up, and the gold in the disturbed gravel is lost when these operations are carried on below water.

Theoretically it is supposed to pick up the disturbed gold in its next trip, but from experience this never happens and the final result is an enormous enrichment on bedrock.

Another drawback is that all gravel has to move to a central point on the bank for washing, instead of putting the gravel dug today back into the hole dug the previous day, as does the dredge.

This accumulation of gravel very soon necessitates the removal of the whole plant to a fresh place that involves much expense.

The drag-line method is conducted somewhat as follows:

A tall mast is set up on the bank on which operations are to be conducted; on the other bank stakes are driven, or anchor or deadmen set out to which is attached a wire apparatus termed the bridle. From the mast to the bridle is attached the main bearing cable. This must be heavy and generally calls for staying the mast.

A single bucket is used, digging on one side only, and this is run from the mast to the required point of contact with the gravel to be moved. The bucket travels on a running carriage from which it is lowered to make contact. It is placed in the digging position by guide lines, to the front or top is attached the hauling line, and the bucket commences to dig on its downward journey, and when full is hoisted to the carriage and drawn up to the mast where the same apparatus used to place it for digging is operated to upset it, after which it is then hauled back to its digging point by the back-haul line to commence digging again.

The power plant is usually situated at the rear of the mast and the length of the haul is a heavy factor in the cost of operation as the height of the mast must be such as to obviate the necessity of moving at too frequent intervals, as this naturally adds to the cost of operations.

The only radius of operations is obtained by moving the tackle on the bridle and the bridle itself has to be frequently moved, and this entails much delay and adds materially to the cost.

The drag-line is rarely used except on small fields condemned as dredging fields by inaccessibility of the heavier and costlier equipment, but the cost of drag-line dredging operations is necessarily high and cannot be used on poor ground.

In my method of dredging operations I escape the first high cost of continuous bucket-type dredging equipment by reason of simpler equipment used and also the high cost of the operation of either of the two modes of dredging described by reason of the equipment used and the lesser cost of operating the same.

In carrying out my method of dredging operations I make use of a type of apparatus illustrated in the accompanying drawings forming part of, this application, and in which:

Figure l is a side elevation of the framework of the dredging equipment as mounted upon a dredge or scow, and shows the front overhanging, inclined runway with the carriage at the bottom of the runway over which is woven the cable carrying the scoop bucket.

Figure 2 is a detail view of the front overhanging, inclined runway of the dredge showing the carriage at the top of the runway and the bucket resting upon the dumping tip platform.

Figure 3 is a similar view to Figure 2 but shows the carriage lowered slightly down the runway to that shown in Figure 2 so as to permit lowering of the bucket down clear of the dumping tip platform.

Figure 4 is an end elevation of the inclined runway viewed from the front of the same and shows the articulated carriage in position at the bottom of the runway for hauling or lifting the scoop bucket which is shown suspended below the bottom of the runway.

Figure 5 is a detail view of the articulated carriage upon the runway with the top enclosing rails removed to more fully show all the details of the carriage.

Figure 6 is a cross sectional view of one wheel of the carriage enclosed within the running rails of the runway.

In these drawings like numerals indicate like parts, and the numeral 2 indicates a timber frame-work having an inclined, built-in runway 3 mounted upon a scow or pontoon l having a power or machinery shelter 5 built at the rear end of the framework 2, in which are housed the necessary operative and power units usual to this class of equipment.

The inclined runway portion of the framework overhangs the front or bow end of the scow 4.

In the inclined runway 3 is mounted an articulated carriage 6 having grooved sheaves I mounted at the centre of the intermediate axles 8.

The carriage comprises four axles 8 mounted in three pairs of side links 9 which are all pivotally connected through the axles.

Flanged wheels ID are mounted upon the ends of the axles and these run on rails H mounted in the inclined runway 3 on both the top and bottom members I2 and I3 which comprise the runway.

The flange wheels l0 run between the rails II and therefore it is impossible for the carriage 6 to jump or leave the track or rails ll.

At the bottom of the runway is formed a curved rail drop pocket M in which the lower and bottom end of the articulated carriage 6 fits when it is at the bottom of the runway.

The short extreme bottom end l5 of the rail drop pocket is practically in a horizontal plane as compared to the inclined portion of the runway to which it is connected by what is practically a near vertical portion Iii, which forms a buifer to the centre articulated portion of the carriage 6 (see Figure 1) when the carriage is in the pocket at the end of the runway.

Near the top of the inclined runway is formed another drop pocket I! in which the carriage fits after the manner in the lower pocket at the bottom of the runway.

Immediately below the top drop pocket I! is i;

a pivoted tip platform H! for the reception of the scoop bucket l9 which is mounted upon the end of the cable 20 which is woven over the centre sheaves l of the carriage 6 and over the top sheave 2| mounted in the head of the framework 2, and then run to the winding drum of the machinery mounted in the shelter 5, none of which is shown in these drawings.

The framework 2 and shelter 5 carrying the machinery may, if desired, be mounted uponskid bolsters 22, preferably faced with iron upon which the whole may be partially rotated by reason of pivotally mounting the whole framework upon a centre pivot 23 positioned at or near the centre of the framework 2, which gives to the framework a large radius to work in without altering the moorings of the scow 4.

In operation the apparatus works as follows:

Assuming the carriage 6 is in the top drop pocket I! where it is held by reason of the strain upon the cable 20 through the weight of the bucket l9 hanging upon the end of the cable 20:

Now, assuming the operator in charge slackens oil? the cable 26 permitting the bucket H to drop vertically upon the bottom of the creek or river bottom in which the dredge may be operating, the carriage 6, being freed of the weight of the bucket l9, will run down the inclined runway 3 under gravity carrying with it a loop of the cable 20 by reason of the cable 20 being woven over the centre sheaves mounted upon the intermediate axles 8.

The carriage 6 will ultimately come to rest in the curved rail drop pocket l4 and will assume a position to that shown in Figure 1, in which the carriage 6 takes up a locked position by reason of the articulation and disposition of the axle and side link members comprising the carriage.

In this position the carriage 6 and loop of the cable 2! are in the horizontal length of the runway ahead of the dropped bucket l9 resting upon the creek or river-bed; hence in position to drag the bucket I9 over the gravel beds below if the cable 20 is hauled upon, and by this means dredging may be effected.

Assuming the cable 20 is being hauled up, the bucket I9 will be dragged to a position immediately below the locked carriage 6 and will be lifted from the river-bed. by continual hauling until the bail of the bucket contacts the lower intermediate and pivoted axle of the carriage 6 which it lifts 0r forces upwards from the bottom of the pocket I4, which immediately frees the carriage 6 from its locked position and causes it and the bucket I9 to ascend the inclined runway under the continual hauling of the cable 20 until the carriage 6 comes to rest in the top drop pocket I'I, after which the cable 20 is just slightly slackened off, which permits the bucket I9 to come to rest upon the pivoted tip platform I8, as shown in Figure 2.

If the cable 20 is now further slackened off, the bucket I9 is caused to tip and discharge its contents, after which the cable 20 is re-wound sufficiently to straighten up the bucket and lift it off the tip platform.

If, now, the cable is slackened off two-thirds the length of the carriage 6, it will cause the top end of the carriage to drop into the pocket I'I without lowering the bucket by reason of the weight of the carriage.

The carriage will now occupy the position in the top drop pocket IT, as indicated in Figure 3, and in this position the bucket has been advanced forward a suificient distance in the runway to clear the tip platform I8, if lowered, after which the operations are those as set out in the beginning of this description of operations.

The method of dredging as here outlined has many advantages over previously known methods, the principle of which is economy of power of operation, as is instanced in the summary of the twelve movements required to complete the digging cycle, ten of which are operated by gravity and two by applied power, as set out below.

Gravity movements Dropping the bucket to the digging position.

. Dropping the carriage.

. Carrying the line to the digging position.

. Locking the carriage at the bottom of the runway.

5. Changing the angle of half of the carriage at the bottom of the runway.

6. Changing the angle of half of the carriage at the top of the runway.

'7. Setting the carriage to hold the bucket in position to dump.

8. Return of the carriage to a position to lift off dumping platform.

9. Dropping the bucket to the dumping platform.

10. Upsetting or dumping of bucket.

Power movements 11. Dragging the bucket from its point of contact with the gravel to its position to dump.

l2. Pulling the bucket after dumping to its position to drop to the digging position.

Having now described my invention, what I claim and desire to be protected in by Letters Patent, is:

1. The method of dredging with floating equipment that includes a float having a boom extending beyond the float, an inclined trackway from the front end of the boom to a place above the float, a carriage movable along said trackway, a bucket and a single bucket-carrying cable cooperating with said carriage; said method consisting, first, in so operating the cable and carriage as to lower the bucket adjacent the float while holding the carriage against lowering; second, causing the carriage to move to the extreme lower end of the trackway; third, retaining the carriage there while hauling in on the cable to drag the bucket along the bottom from a place adjacent the float to a place adjacent the outer end of the boom; fourth, raising the bucket to the boom and releasing the carriage and moving the carriage and bucket backwardly and upwardly together toward the top of the trackway to a place for dumping; and, fifth, slacking the cable and dumping the bucket and preparing the bucket to be again lowered, thereby completing a cycle of operation substantially as described.

2. In dredging apparatus, a float having an outwardly projecting structure of general triangular form, the base of which is at the bottom and the hypothenuse of which is constituted by an inclined trackway extending downwardly and outwardly from an elevation directly above the float, said trackway having a drop pocket at its lower end and a second drop pocket adjacent its upper end, an articulated carriage running in said trackway and cooperating with said drop pockets for purposes specified, a bucket, a bucket-holding cable secured to the bucket and cooperatively engaging with said carriage, a sheave on said structure above the upper drop pocket over which sheave said cable passes, and a dump platform located beneath said upper drop pocket, all being arranged so that said bucket may be lowered adjacent said float to the bottom beneath, dragged along the bottom toward the outer extremity of said structure, lifted to said outer extremity, raised with said carriage along said trackway and toward the upper extremity of the same to a place over the dump platform to bring the carriage to the upper drop pocket, and then lowered onto the platform and dumped, thereby completing the cycle of operation.

CHARLES SANDERS.

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