US1902259A - Method of and apparatus for controlling dredges - Google Patents

Description

Marchal, 1933. A. NEVEUNG 1,902,259v

METHOD 0F AND PPARATUS FOR CONTROLLING DREDGES I l Filed Feb. 18, 1932 2 Sheets-Sheet 1 s, Q Q A 'Q N5 Mrch 21,1933. A. NEVELING 1,902,259

METHOD 0F. AND APPARATUS FOR CONTROLLING DREDGES Filed Feb: 18, 1952 2 Sheets-Sheet 2 Patented 21, 1933 UNITED STATES ALOYS NEV'ELING, CHICAGO, ILLINOIS METHOD OF AND APPARATUS FOR CONTROLLING DREDGES Application led February 18, 1932. Serial No. 593,815.

This invention relates to improvements in methods of-and apparatus for controlling dredges and its purpose is to provide an improved method and'improved means for controlling the movements of the digging bucket of a dredge which is elevated by hoisting mechanism and moved through a cycle of operations duringits excavating, elevating and dumping movements. The invention may also be employed to advantage in connection with excavating and hoisting operations employed in other surroundings. This application is a continuation in part of my prior co-pending application Serial No. 546,652, filed June 24, 1931.

In the operation oi' a dredge, for example, the amount of energy expended and the work done at different stages of the cycle of operations of the digging bucket vary throughout a Wide range, depending upon the position of the bucket, the resistance encountered thereby and the presence or absence of a load in the bucket, and this makes it desirable to equip the hoisting apparatus with devices for supplying the required amount of power at different stages of the digging and elevating operation and for counterbalancing or assisting the load represented by the bucket and its connected parts during the return movement of the bucket from its dumpingA position to its digging position. The first stages of the operations may be called a 'work cycle because work must be expended during these stages 35 in excavating the material being operated upon and elevating it to the required height, and the subsequent stages during which the bucket is dumped and then returned to its excavating position may be termed a compression cycle because the forces exerted by the bucket and its immediately connected parts are then opposed to the normal application of energy by the source of power by which the bucket is moved during the work f cycle. Efforts have heretofore been made to apply the required amount of energy in a different way during the different stages of the cycle of operations of the bucket and to control properly the dumping and return movements of the bucket, by employing a stages of the work cycle, and the energy derived from a bucket and its connected parts during the compression cycle has been utilized for driving the motor as a i generator and storing up energy through the reversal of the operations of the motor-generator set.

' While this form of apparatus has many ad- 65 vantages over the previously known forms of apparatus for operating dredges and other hoisting devices, the apparatus is very costly and complicated and lacks the simplicity which should be present in apparatus of this character.

The principal object ofthe present invention is to overcome the above mentioned dificulties by providing a ne-w method and means for controlling the operation of dredge mechanism, according to which the supply of energy for moving and controlling the load during the various stages of the work and compression cycles is furnished and controlled by the prime movers alone, wit-hout necessarily employing any motor generator sct or other auxiliary apparatus, so that the initial cost of the dredge equipment is greatly reduced and the speed and eiiciency of operation greatly improved as compared with previously known apparatus employed for dredge purposes. A further object of the invention is to provide cont-rolling means for hoisting or dredging apparatus in which the movements of the digging bucket or the like are effected and controlled by steam turbines which are connected with the hoisting mechanism in opposition to each other, so that one turbine'supplies the power for lnoving the bucket through its work cycle, and for braking the movement of the bucket during its dumping and downward movements, while the other turbine supplies the' power for counterbalancing and controlling the movement of the bucket and its connected parts durin its return movement or compression cyc e. An important feature of the invention is that one turbine is employed for accelerating the movement of the bucket and the connected hoisting mechanism during the return movement of the empty bucket to digging position, while a braking action is exerted upon the bucket during the final stages of this return movement, either by the other oppositely connected turbine, which serves to elevate the loaded bucket, or by an'automatically operated brake which is responsive to the speed of the return movement. Other objects of the invention relate to various features of construct-ion and arra-ngement of the apparatus and to various details of the improved method, which-will appear more fully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings, in which one embodiment of the improved apparatus is illustrated. IIn the drawings,

Fig. 1 shows a somewhat diagrammatic side elevation of a dredge employed in excavating material from the bottom of a river or harbor and elevating it into a scow by which it is conveyed away, and illustrating the positions of the paths of movement of the bucket at different stages of the work and compression cycles;

Fig. 2 is a chart or diagram illustrating the fluctuations in power required for the movement of the'bucket during different stages of the work and compression cycles for the duration of one complete cycle of operations of the bucket;

Fig. 3 represents, somewhat diagrammatically, a plan view of one form of hoisting mechanism adapted to be employed in practicing the present invention;

Fig. 4 shows an enlarged top plan View of a portion of the hoisting mechanism shown in Fig. 3 with a part thereof illustrated m horizontal section; and

Fig. 5 shows a side elevation of the friction brake which isembodied in the construction illustrated in Fig. 4 with the steam cylinder and associated parts illustrated 1n vertical section.

As illustrated in Fig. 1, the dredge 10 comprises a hull 11 floated upon a body of water having its surface at 12. The normal bed or bottom of the river or harbor in which the dredge 10 is operating is shown at 13, and the dredge is being operated to excavate this bed or bottom to reduce a lower level, shown at 14. The buc et 15 of the dredge is shown as being operated along the curved bank which connects the old bottom 13 with the new bottom 14 and this bucket or scoop is carried at the end of a hoistingr beam or handle 16, the upper end of which passes through a casing 17, known as a carriage,

effected primarily by a cable 22 connected at its lower or outer end to the bucket and `arranged to pass over a pulley 23 mounted on the outer end of the frame 18. After passing over this pulley, the cable 22 is directed downwardly and inwardly and passed around the hoisting drum 24 which is mounted'on a suitable base within the hull 11. This drum is driven through intermediate mechanism from prime movers 25 which, in the present invention, take the form of two oppositely connected steam turbines, as heretofore indicated. The hull 11 is provided at its four corners with the usual posts or spuds 26 which are capable of being adjusted downwardly to the positions shown by ldotted lines, wherein they rest upon the bottom 14 to support the hull against vertical movement during the operations of the bucket 15.

The beam or handle 16 may be raised and lowered to vary its effective length below the carriagel' by means of an engine 28l which is mounted upon the frame 18 and which drives a pinion arranged to mesh with a rack bar 29 secured to the lower face of the beam or handle 16. In addition to the movement of the bucket 15 by the reciprocation of the beam or handle 16 through the carriage 17, the bucket 15 may be withdrawn toward the hull 11 by a vcable 31 which is attached to -the lower part of the beam and which extends through a set of fairlead sheaves or pulleys 32 mounted on the end of the hull, after which it is led rearwardly and passed around the drum or winch 33 mounted on the hull. The operations of the winch 33 and the engine 28 may be carried on in conjunction with the hoisting operations which are effected rimarily by the cable 22 and the turbmedriven drum 24, in order to bring about the desired movements of the bucket 15.

In Fig. 1, the curve 35, drawn as a solid line, represents the path of movement of the bucket l5 during the excavating, elevating and dumping operations, while the curve 36, shown as a dotted line, represents the path of movement of the bucket during its return movement from its dumping position to its initial digging position. It will be apparent that the power which must be expended to move and support the bucket in different parts of its digging and `dumping cycle, represented by the curve 35, may vary throughout a wide range and that the power which must be sup lied to control or assist the movement ofp the bucket during its return cycle, may similarly Vary throughout a wide range. These fluctuations in power have been plotted in the form of a curve 38 in Fig. 2, where the abscissaerepresent intervals (if/time, and where the ordinates represent units of power, such as horsepower, sup'- plied to the bucket at different stages of its work and compression cycles. The various positions of the bucket during its work and compress/ion cycles have beenindicated by letters a,' b, c, d and e onthe curves 35 and 36 in Fig. 1 and the corresponding positions of the bucket have been represented by the same letters onthe curve 38 in Fig. 2.

As the bucket l5 moves from its lower position a to the position b where its digging action is completed, the power which must be applied to move the bucket will normally tend to increase gradually because the bucket gradually assumes a more upright path of movement and the power supply may fluctuate, depending upon the variations in resistance encountered by the bucket due to variations in the content of the material of which the bottom kor bed of the river 'or harbor is formed, so that the first-part of the power curve 38Lmay have the form .38* which represents the power supplied during successive intervals of time as the bucket moves from position a to position b. 'As the bucket moves upwardly from position b, the power required tends to beless than that required during the last stages of the digging operation because the bucket is ,then partially supported by the buoyancy creases as the bucket emerges from the water,

, that because ofthe absence of this buoyancy, so

' 39 by which the excavated material is conveyed away. During this movement of the bucket, there' is a rapid falling off of the reruired power until it reaches a negative va ue, as shown by the portion 3 8c of the curve in Fig. 2 That portion of the curve which lies below the'zero line. represents a stage in which work is being done by the W bucket and it is during this stage that power must be supplied to counteract or control the movement of the bucket as it moves downwardly. As the bucket reaches its Afinal dumping position d, the power curve has risen slightly above the zero line and of the water, but the required power in-l the power curve from position b to po-l then, upon beginning the return'movement of the bucket to its digging position, it is necessary first to elevate the bucket from its position within the hopper of the scow 39 so that a ypositive application of power is required in moving the bucket from position d to position e, as shown by the portion 38d of the power curve 38. The bucket then begins to lower as it travels downwardly along the dotted curve 36 to its digging position a and during this movement the powery curve 38 again 'descends rapidly and falls below the Zero line, as shown at 38e. in Fig. 2.. It will be noticed that the negative power required during the operation of restoring the bucket to its digging position is equal to or greater than the maximum power required during the work cycle of the bucket.

The operating mechanism for the bucket must therefore have at least as great a power capacity for application during the compression cycle as it has during the work cycle of the bucket.

which-the drum 24 corresponds to the drum illustrated in Fig. 1 with two cables 22 wound around it for connection with the bucket 15. This drum. is mounted on a shaft journaled in bearings 40 which arev carried4 by the base or frame 41 adapted to los be secured in fixed position within therhull of the dredge. The drum 24 is rotated by a gear 42 mounted on the same shaft as the drum and actuated bya pinion 43 fixed on a countershaft 44.y The shaft 44 has secured thereon a herringbone gear 45 which meshes with a driving pinion 46 fixed upon the common shaft 47 of two jsteam turbines 25a and 25b which areunount'ed -upon a part of the base 41. These two turbines are supplied with steam through pipes 48 leading from amain supply pipe 49 and each of the pipes 48 has--connected therein a valve or steam supply governor 50 for controlling the admission of steam to the adjacent turbine. These two valvesor governors 50 arepreferably interconnected as shown diagrammatically at 51|, so that they. may be controlled by'a common lever to prevent the turbines while permitting either turbine to operate and supply power while the other y turbine/is' idling.' The turbine 25a serves as a prime mover for applying power to the drum from the initial diggin position a to the osition c where the hoisting of the bucket as been completed and the turbine 25a is also utilized for operating the drum 24 during theielevation of the bucket from the dumping position d to the position e on the return movement, and it may alsol be employed for applying a braking effort to the bucket at the limits of its dumping movement and of its downward return movement in order to bring the bucket to rest at its initial digging position. The other turbine 25b acts as a prime mover during the lowering movements of the bucket, that is, during the dumping movement from the position o to the position d, and during the return vmovement from the position e to the initial position a, during which parts of the cycle, this turbine 25b serves to drive the dredge mechanism and accelerate it so that -the bucket is free to move by gravity without having to drive any ofthe parts of the connected mechanism. l

The controlling lever of the turbines may be'shifted several times during theY complete cycle of operations of the bucket in order to bring the proper turbine into operation to apply power during the different stages of the cycle just referred to and also for the purpose of causing the hoisting turbine 25 to retard the movement of the bucket at the ends of its dumping and return movements and, if desired, the braking action of the turbine 25 may be caused to take place automaticallyA as hereinafter more .fully eX- plained. At the beginning of the digging operation, the controlling connections are set lto start the turbines 25a in operation in the position a and this turbine continues to supply power, with the other turbine idling, until the bucket reaches the position c, whereupon the operator shifts the connection 51 so that -the turbine 25a then begins to idle while steam is admitted to the turbine 25b so 'that the latter turbine applies cut offrom the steam supply and steam is again admitted to the turbine 25'L so that the latter turbine then' acts as abrake to retard the bucket and bring it gradually to" rest at the end of its dum ving movement. This turbine 25* then continues to o rate s0 that,

after the contents of `the buc et havebeen. dumped, the bucket is elevated bythis turbine along the path d-e at which point the connections are again changed so that the turbine 25 begins to idle and power is applied through the turbine 25b to drive the drum and the cable mechanism during the lowering movement along the path e-q, thus assisting the normal motion of the bucket under. the influence of gravity and speeding up the cycle during which no work is being done by the bucket. Before the bucket reaches the position a, the connections are again changed to admit steam to the turbine 25 and to shut oi' the supply of steam to the turbine 25?, so that the turbine' 25at acts as a brake to retard the motion of the bucket as it approaches the initial digging position a; The connections 51 are preferably such that there is a neutral zone between the two positions of the operating lever whi'ch effectl the admission of steam to the two turbines so that when the lever is in its neutral position, neither turbine will 0 erute. In the manner just described, t e application of energy to the! drum 24 from the turbines 25EL and 25b may be controlled according to the method of the present invention to supply the required amount of power for moving and elevating the bucket during the work stages and for expediting and* retarding its movement at different stages of its movement where no work is being done in excavating or hoisting a load. Of course, the connections 51 may be shifted at other times during the operation, depending upon the conditions which are encountered by the bucket during its movement.

Instead of depending entirely upon manual control for bringing the proper turbine into action at each different stage of the cycle of operations, automatic controlling mechanism may be employed and there is illustrated in` the drawings, one form of automatic controlling mechanism which may be used to effect the braking or retardation of the movement of the bucket at the ends of its dumping and return movements, either by actuating a friction brake or by admitting steam to the turbine 25l which supplies the power for moving the bucket in the opposite direction. This mechanism comprises a governor 55 mounted upon the shaft 44 to rotate therewith. This governor includes a casing 56 having a cover 57 provided with a.

.central aperture 57Bthrough whichextends iso,

coil spring 62 which tends to prevent their separation under the influence of centrifugal force. Whenthe speed becomes great cnou h to cause the centrifugal force acting on t e vweights 60a to separate, the bell crank levers are thereby actuated to shift the governor shaft 58 inwardly and thus actuate the valve 64 which is adapted to control the-admission of steam to a brake controlling device or to the turbine 25a. The valve 64 comprises a casing 65 havin mounted therein a iston 66 which is secure on the shaft 58. he piston 66 is provided with an annular groove 66 which, when the piston is in the proper position, is adapted to establish communication through the cylinder from the steam supply pipe 67 to the steam outlet pipe 68. The outlet pipe 68 'has ktwo branches68* and 68b which are connected thereto by a T-connection 69 and these branches are controlled by separate manually operated valves 70 and 71, respectively, s0 that either branch pipe may be closed when desired.

The branch pipe 68 leads to a steam ram 72 whichis secured on the base 41 and which comprises a cylinder 73 having mounted therein a piston 74 adapted to be moved within the cylinder by the steam which is admitted thereto. The piston 74 is connected to a piston rod 75 which leads through a packing gland 76 in the end wall of the c linder and is pivotally connected to a link 77. The other end of this link is pivoted on one arm of a bell crank lever 78 which isA pivotally supported at 79 on a bracket 80 secured on the base 41. The

, other arm of this bell crank lever 78 is connected to one .end of a brake strap 81 which extends around the peripheral surface of a brake drum 82 secured on the shaft 44 'with its other end attached to the brake 80 at 83. When the piston 74 of the arm is operated by steam pressurev the bell crank lever 78 is actuated to tighten the brake strap around the drum 82 and thus arrest the rotation of the connected drum 24 and the bucket 15 'connected thereto. Suitable means, such as a spring 84, located in the cylinder 72, may be emplo ed for effecting reverse movement yof the piston 74 and thereby releasing the grip of the brake strap 81 on the drum 82 at tile end of theoperation which will ordinar spee and the consequent closing of the valve 64 b the centrifugal overnor 55. If del1 si ,any other suitab e form of governor- 68" to the turbine 24, thus tending to robe determined by the cessation of` that this means and method of operation,`

eliminate the necessity' for usin the expensive and complicated electrica apparatus which has heretofore been employed, while at the same time obtaining the advantage of greater speed and economy of operation. The present inventidn may be applied to dredges or hoists of various capaclties but it is particularly effective when employed in connection with dredges or hoists 'Where great tension is set up in the cables as a result of the heavy loads being excavated or hoisted, for example, dredges in which the load carried by eachhoisting cable may be from 100 to 20.0 tous. Although the invention has been illustrated as comprising two separately constructed turbines, it will be understood that two turbines may be combined in one structure for permitting the ap- 1. The combination with a dredge, of f hoisting mechanism mounted on said dredge, and a 'pair of oppositeljr connected steam turbines Yconnected to said hoisting mechanism for controlling the opposite movements thereof.

2. The combination' with a dredge, of hoistingmechanism mounted on said dredge, a bucket operated by said hoisting mechanism, and a pair of oppositely connected `steam turbines having a common connection with said hoisting mechanism for controlling the opposite movements of said bucket. 3. The combination with a dredge, of oisting mechanism mounted on the dredge, a bucket operated by said hoisting mechanism, and controlling mechanismfor said bucket comprising a pair of oppositely cotillnected steam turbines having connectie s whereby they may be employed alternately forA e ecting positive movement of said bucket and for braking the downward movements of said bucket.

` 4. Thevcombination with a dredge, of

hoisting mechanism mounted on the dredge,

a bucket operated by said hoisting mechanism, a pair of oppositely connected steam turbineshaving connections whereby one turbine may be employed for operatin said hoisting mechanism to move said buc et in one direction and the other turbine may be employed for accelerating the movement of the bucketl in the opposite direction, and means for automatically bringing said first named. turbine into operation for retarding the movement of said bucket in said last named direction.

5,"The combination with a dred e, of hoisting mechanism mounted on the red-ge, a bucket operated by said hoisting mechanism, a pair of oppositely connectedv steam turbines having connections whereby one turbine may be employed for operatin said hoisting mechanism to move said buc et in one direction and the'other turbine may be employed for accelerating the movement of the bucket in the opposite direction, and means including an automatic governor responsive to the speed of movement of the bucket for admitting steam to said firstnamed turbine to apply power for retarding the movement of said bucket in said last named' direction. ,Y

6. The combination. with a dredge, of hoisting mechanism mounted on the dredge, a bucket operated by said hoisting mechanism, a palr of oppositely connected .steam turbines` having connectlons whereby one turbine may be employed for operating said hoisting mechanism to move said bucket in one direction and the other turbine may be employed for accelerating the movement of the bucket in the opposite direction, and a brake for retarding the final movement of said bucket in said last named direction.

7. The combination with a dredge, of hoisting mechanism mounted on the dredge, a bucket operated by said hoisting mechanism, a pair of oppositely connected steam turbines having connections whereby one turbine may be employed for operating said hoisting mechanism to move said bucket in one direction and the other turbine may be employed for accelerating the movement of the bucket in the op osite direction, a brake for retarding the nal movement of said bucket in said last named direction, and automatic means responsive to the speed of movement of said bucket for actuatin said brake to retard the final movement o said bucket in said last named direction.

- 8. The methodof controlling the operation of the digging bucket of a dredge, having'V elevating and downward movement, by oppositely connected-steam turbines,

' which consists in employing one turbine to eifect positive movement of the bucket during its elevating movements and to brake the, movement of the bucket during its downward movements and employing theother turbine to control the speed of movement of said bucket during its downward movements.

9. The method of controlling the operation of a digging bucket of a dredge by oppositely connected steam turbines which consists in employing one turbine to move hoisting mechanism mounted on the dredge,

a bucket operated by said hoisting mechanism, a pair of oppositely connected steam turbines having connections whereby one turbine may be employed for operatin said hoisting mechanism to move said buc et in one direction and the other turbine may be employed for accelerating the movementof the bucket in the opposite direction, and

means for causing said first named turbine to operate to apply power for retarding the movement of said bucket in said last named direction.

11. The combination with a dredge,ofI a" boom mounted on said dredge, a bucket, hoisting mechanism comprising a cable supported on said boom and connected to said bucket, a pair of oppositely rotating steam turbines havinga common shaft, and driving connections from said shaft to said hoisting mechanism whereby one of said turbines may be employed for elevating said bucket and controlllng its downward move- Y ment andthe other turbine ma `be employed for accelerating said ownward movement.

In testimony whereof, '1 have subscribed my name.

ALOYS NEVELING.

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