US2217629A - Automatic control means for dredge buckets - Google Patents

Description

CCL 8, 1940. Q wlLLlAMS 2,217,529

AUTOMATIC CONTROLMEANS FOR DREDGE BUCKETS Filed Aug. l5., 1938 Patented Oct. 8, 1940 UNITED STATES PATENT "OFFICE John Ci Williams, Reno, Nev., assignor to John C. Williams Corporation, a corporation of Nevada Application August 15, 193s, iserial No. 224,967

13 Claims.

I'his invention, an automatic control for dredge buckets is suitable for control of all types of power operated ldevices which are suspendedly transported and intend-ed t'o operate when the transl; porting means deposits them on a supporting surface; however, this control is particularly designed for the control of deep-sea dredges, and particularly such dredges which are operated through the medium of the water of submergence.

This control is specically designed for use in connection with a dredge which is provided with a water-of-submergence-actuated prime mover,

and in which the dredge Ais lowered to, and raised from a sub-sea surface through the medium of a hoisting cable.

In this connection, the hoisting cable, through this control, controls the admission of watereofsubmergence to the prime mover for operation only when the dredge reaches a sub-sea surface,

or when the cable is purposely excessivelyslacked to permit its operation at an intermediate depth, and which also automatically releases the dredge from an immovable object, and, which also uidlocks the prime mover against-operation except l when the cable is slacked or excessively stressed.

The purposes of the invention are, to provide means in association with a water-of-submergence-operated prime mover mounted on a deep-l sea dredge in which the hoisting cable functions as raising and lowering means,` and, as control means for all operations of the dredge; to include in said control means a valve opened'to the prime mover to admit water-of-submergence when the*Y cable is slack and to lock the Water inthe primey mover when-the cable is taut or under normal or predetermined stress, andto equalize the pressure in the prime mover in the event of excessive hoisting effort by the cable to release the dredge from a relatively immovable object, and to provide means for opening the dredge whenreleased.

This invention is an improvement over copending applications, Serial Number 93,971, led August 3, 1936, which issued as Patent No. 2, 129, 158, under date of September 6th, 1938, and Serial Number 173,840, filed November 10,1937, both o f which cover clamshell dredges, and, the rst of which` provided no means for releasing the dredge from an immovable object, and the second of which provided means controlled by separate cables, conduits, and pumps, for accomplishing the release. l

'I'his invention illustrates a diierent system of operating connections between the prime mover and the bucket than that of Yprevious applications.

However, the control system is as readily applied to either type of dredge,l as well as other types which are not operated in Water but by power from an external source, in which case the external source of power is connected vto the Waterof -submergence inlet. l

` In describing the invention, reference will be had to the accompanying drawing in which:

Fig. l is an'end velevation of the invention as applied to a cylinder-and-piston-operated clamshell bucket, with portions broken away to clearly illustrate the connections.

Fig. 2 is a sectional elevation through the invention. v

F'ig. 3 is a modication of the system of balancing the pressure in the cylinder.

As illustrated, the prime mover consists of a cylinder Ill having a piston Il provided with a piston rod I2 which is operatively connected through a crosshead I3 and links I4 to the clamshell bucket l5 for opening and closing the bucket, the two members of which bucket are respectively hinged at I6' and Il; the bucket and operative connections being overbalanced by, and thev bucket being normally urged to open, by the coun terweights I8 and I9 operating through the respective levers 20 and 2| which are respectively fulcrumed at 22 and 23 on the respective rocker links 24 and 25, and pivoted respectively at 26 and 2l to the head 28 of the cylinder l0, at 29 and 30; the inner ends of the levers 20 and 2| being pivotally connected at 3l to the extension 32of the piston rod l2.

Water of submergence is admitted to the cylin der` vl0 by meansr of a valve 33 which has a connection 34,1;0 the cylinder l0, and a port35 in communication with the surrounding fiuid, and is illustrated as consisting of a valve of the type illustrated and described in copending application Serial Numberr224,968 filed August 15, 1938, for Valves, although any other type of valve suitable for the purpose may be used. y

A second,similar valve 36 controls a bypass`3l between the opposite ends of the cylinder lll, a1- though two valves in series, as 36 and 38, as. illustrated inllig.V 3 may be used, the only requirement being that both valves shall operate to open and close simultaneously and both be in communication with the surrounding fluid and with the, cylinder.

A bail 39 forms the suspensory support for the dredge and a mounting for the control device, al'- though the mounting of the control device is not limited to such construction.

TheV control device comprises an overload release mechanism and resetting means therefore,

and, a trip, or valve control mechanism, both of which mechanisms are balanced to external fluid pressures,

The overload release mechanism consists of a cylinder 36 having two bypasses respectively 4I and 42 formed in the walls thereof and forming each a communicating passage between the oposite ends of the cylinder 40.

The bypass 4l is a reset bypass and has a valve 43 loaded by a light spring 44 and positively seating against pressure from within the cylinder 46, but opened to the inside of the cylinder through urgence of fluid under pressure within the bypass 4I.

The bypass i2 is the overload release bypass and it has a valve 45 which is loaded by la heavy spring 46 and positively seats against pressure within the bypass 42 and is urged to seat against pressure within the cylinder, excessive pressure within the cylinder' unseating the valve to permit fluid to pass from the upper to the lower end of the cylinder 46.

Mounted within the cylinder 40 is a piston 41 which has extensions from its opposite facesforming plungers 48 and 49 which are of equal cross-sectional area to balance the piston against external fluid pressures, and these plungers are effectively sealed against ingress and egress of fluid to or from the yrree spaces between cylinder, piston and plungers, the sealing means being indicated at50 and 5l.

A spring 52 cooperates between one face of the piston 41 and the head 53 of the cylinder 46 and provides means for automatically resetting the l overload release.

The free spaces within the cylinder and bypasses 4I and 42 are filled with a liquid, preferably oil, although water or'any other suitable medium may be used.

The trip, or valve operating mechanism consists of a cylinder 54 formed interiorly of the plunger 48, and a piston 55 operating therein and having plungers 56 and 51 extending from its opposite faces, these plungers having equal cross-sectional areas for balance against external or surrounding pressures, and a spring 58 urges the piston to the bottom of the cylinder, the hoisting cable 59 being attached to the plunger 51.

The bearings for the plungers 56 and 51 require no packing or sealing means, and the piston may operate loosely in the cylinder to permit nuid within the cylinder to bypass, and if desired,

the plunger 51 may extend clear through the element 41, 48, 49, with the spring seating against the bottom of the plunger 46, 49, a construction similar to that illustrated at 59, 6I, 63, in copending application, Serial Number 173,840, filed November 10, 1937, for Clam-shell dredge.

A control lever 66 is intermediately pivoted at 6I to a bracket 62 formed integral with the cylinder head 53 and has one end 63 cooperating with an annular groove 64 .formed in the upper end of the plunger 51 and. its other end slidably cooperating with the valve-actuating rod 65 which is downwardly urgedby a spring 66 cooperating between a fixed collar 61and the other end 68 of the lever 66, this spring acting also` to compensate for overtravel of the lever. A collar 69 cooperates with the top face of the other end 68 of the control lever to cause lifting of the rod by the cable 59 under load.

The release lever 1I has its inner end 12 cooperating with an annular groove 13 formed in the head 14 of plunger 4B, and is pivoted at its other end at 15 to a lbracket 16 integral with or'mounted on the cylinder 40, and a valve connecting rod 11 is pivotally connected at 18 intermediate the ends of the lever.

The operation of the invention is as follows:

Under normal conditions of operation, the dredge is suspended by the cable 59, and the weight of the dredge, even when submerged, compresses the spring 458 and the plunger 51 projects upwardly, raising end 63 and depressing end 68 of valve-control lever 60, and this lever through spring 66 and collar 61 forces the valve 33 to its seat or closes the valve to prevent admission of water of submergence 19 to the cylinder through a suitable port 35.

Since the liquid in cylinder 40 is incompressible, and the valve 45 is loaded sufliciently to prevent bypass of fluid from the upper to the lower end of the cylinder 40 under all' ordinary conditions of loading on the cable 59, there occurs no movement of piston 48, and lever 1I, through rod 11 keeps valve 36 closed and prevents bypass of fluid between the opposite ends of cylinder I0, therefore the opposite ends of cylinderv I are isolated from each other and the fluid of Voperation cannot circulate between the opposite ends or be admitted to the cylinder through this valve.

When the dredge reaches a sub-seat surface 89, and the hoisting cable 59 is slacked, the spring 58 depresses plunger 51, forcing end 63 of lever 6 0 down and raising end 68, and thisend, through collar 69, lifts the valve rod 65 and opens valve 33, admitting water of submergence or fluid of operation 19 to the upper end of cylinder I9, forcing the piston II to the position shown, which, through piston rod I2, crosshead I3 and links I4 close the bucket I5 as shown, against the urgence of the counterweights I8 and I9.

Air entrapped in the lower end of the cylinder is taken care of by permitting it to escape to a suitable breather tank (not shown) but located at a higher level to provide drainage of any water which might be forced into it, somewhat in accordance with the various systems illustrated and described in the previously-mentioned copending application and patent over whichthis present application is an improvement.

When the cable 59 is again drawn taut, the plunger 51 is again raised, closing Valve 33 and locking the water admitted in the cylinder, thus hydraulically locking the prime mover, and consequently the dredge, against operation so long as the cable is loaded, and, when the dredge has been hoisted from the water and is ready for dumping, manual depression of handle opens valve 33 against the action of spring 66 and permits the water to drain from the cylinder I0, as the counterweights I8 and I9 lift the piston, the operative connections and the bucket halvesand open the clamshell bucket I5; Upon release of lever 16, the spring 66 again closesvalve 33 with the bucket open, ready for a subsequent operation.

There is a possibility that the bucket might close on a sunken ship, projecting rock, or other relatively immovable'object, trapping the dredge, and under such conditions, with the piston either water locked or subjected on one side only to the pressure of the water of submergence, the dredge would obviously be lost unlessmeans was provided for its release, and for which this release means is provided.

It will be supposed that the dredge has clamped onto a relatively immovable object.-i VThel cable 59, with normal stress o nly closes valve- 33 and has no eifecton valve 36. Additional, excessive stress is thereby placed on the cable when anattempt is made to hoist the dredge, considerably abovethat required to hoistthe -free dredge with full load, and this additional stress acts on the liquid in cylinder 40 sufficiently to force ;valve 45 open against the action of spring 46, and the liquid escapes from the upper vend of the cylinder through the bypass to the lower end, the pull raising piston 41 and compressing spring 52;7 while the plunger head 14 lifts end 12 of lever 1I and coincidently lifts the valve rod 11, opening valve 36 andv thus opening the bypass 31, equalizingthe pressure onopposite sides of the piston I I, and the counterweights I8 and I9 open the bucket, releasing it'from the object of entrapment.

, After the bucket is free, it is raisedto the-surface and out of the water and rested on a support, and as the cable 59,is Slacked, the spring 52 depresses the piston and forces the liquid beneath the piston 41 through the bypass 4I, past the lightly loaded valve 43, thus resetting the release mechanism and depressing valve rod .11 to close valve 36.

Valve 8| is then manually opened to drain Water from the lower end of the cylinder I0, and valve 33 is manually opened to drain water from the upper end of the cylinder, while thecounterweights I8 and I9 open the bucket fully `forasubsequent operation.

Thus, the release mechanism is self-resetting and is operated only under conditions ofexcessive loading on the cable. l

Instead of providing a bypass -31 controlled by a single valve 36, two valves, 36 and 38 may be supplied for the respective ends of th'ecylinder IIland arranged for simultaneous operation, beingconnected together by means of agrod 82 or other suitable connection, and both having access to the water of submergence. j l

In this arrangement, water is admitted to both ends of the cylinder, and due to balance in pressureA on Vopposite ends of the piston Il, the counterweights I8 and I9 readily openthe bucket.

There is one advantage in this construction, in that the Water will automatically drain from both ends of the cylinder when the dredge is removed from the water, and after the draining is completed, requires only that the dredge be lowered onto a support for a sufcient length of time to permit the spring 52 to reset the release mechanism.

If the dredge is to be operated out of water, and by a developed source of power, it is merely necessary to connect the source of power to the port 35, and use the two valves 36 and 38 for release instead of the bypass, and using one of these valves for draining the cylinder to open they bucket.

If the dredge is to be operated under water by a developed source of power, such as air under pressure, the bypass 31 is used, and the source of power is connected to the port 35.

I claim:

1. Control means for a dredge having a bucket comprising grab elements, and having a hoisting cable, and a prime mover for operating'to close said grab elements, comprising; first control means operatively associated with said hoisting cable and with said prime mover and controlled by said hoisting cable and controlling operation of said prime mover for operation when said cable isslackfand'for' locking said prime mover against operation when said cable is stressed to a normal degree; second'control means operatively associated with said cable and with said prime mover for unlocking and creating an idle condition in 2.,/ A structure as claimed in claim 1; and means associated with -sadgrab elements and operating to open said grab elements when said prime mover is unlocked by saidsecond control means-and said idle condition is createdin said prime mover, for freeingsaid dredge from theobject of ventrapment. I y ,1

'3. Control; means for a dredge having a bucket comprising grab elem-ents and having a iluid-operated prime moverhaving a uid driven'element therein for operating-,the grab elements to close the bucket, and having a hoisting cable; a valve and control means therefor associated withsaid cable yand with said prime mover, said control means opening said valve for admittingk fluid for driving said element for operation of said grab .dition of said element for free movement for release of said grab elements from an object of entrapment; and opening means operatively associated withsaid Abucket for opening said bucket when said unlocked andidle condition is created, to completely free said dredgefrom said object of entrapment.

4. A structure as, defined in Vclaim 3, in which resetting `means is associated with. said control meansl and operativelyvconnected to saidcable, forfresetting said release means for subsequent operation when said cable is slacked following a condition ofabnormal stress on said cable.

5. In a dredge having a bucket and a water-ofsubmergence-operated prime mover, and a cable for hoisting and lowering said dredge; a valve for admitting water-of-submergence to said prim-e mover; valve control means associated with and controlled by said hoisting cable closing and maintaining said valve closed when said dredge is supported by said hoisting cable to lock said prime mover against operation, and opening and maintaining said valve open to admit water-ofsubmergence to said prime mover for operation when said dredge is unsupported by said cable; and release means operating only underv conditions of abnormal hoisting effort and associated with said cable and with said prime mover, freeing said prime mover internally for idle operation in either direction under the iniiuence of external urgence other than said water-of-submergence; and counterweights creating said external urgence and normally urging said bucket to open.

6. A structure as claimed in claim 5, and means resetting said release means for subsequent release operation when said dredge is unsupported by said cable.

'7. A structure as claimed in claim 5, said valve control means comprising a spring-depressed plunger having said cable attached thereto, a lever cooperating with said plunger and closing said valve when said plunger is raised through hoisting effort or support of the dredge by said cable, and opening` said valve when said cable 4 is slacked to a condition of non-support of the dredge.

8. A structure as claimed in claim 5, said release means comprising a cylinder, a piston operating within said cylinder, a spring urging said piston against the hoisting eiort of said cable; two bypasses connecting the opposite ends of said cylinder and each having a valve for control thereof; one of said valves being loaded to open for transfer of fluid from the upper to the lower end of said cylinder only under conditions of abnormal hoisting eiort on the part of said cable, and the other valve being lightly loaded for seating only against pressure in the upper part of said cylinder to permit transfer of fluid from the lower to the upper end of said cylinder under the inuence of said spring.-

9. Dredge control means, in combination with a prime mover and a hoisting cable; dredge release means comprising a cylinder having two bypasses connecting the upper and lower ends, said cylinder being sealed against surrounding luid pressures; a release valve for one bypass resisting transfer of fluid from the upper end to the lower end of said cylinder under predetermined pressure and releasing for transfer of fluid when said predetermined pressure is exceeded; a reset valve for the other bypass for substantially unresisted transfer of fluid from the lower end to the upper end of said cylinder; a piston having a plunger extension and slidable in said cylinder and a spring depressing said piston and forming resetting means for said release means for subsequent operation; said cylinder and bypasses being lled with a liquid; said release means being associated With, and controlled by said cable, and, means controlled by and associated with said piston controlling said prime mover and converting said prime mover toian idle condition in the event of excessive hoisting effort on the part of the cable; and means opening said dredge when said prime mover is converted to an idle condition.

10. A structure as claimed in claim 9, in which said piston is provided with opposed plunger extensions of equal area and subjected to surrounding pressures externally of said cylinder for balancing the effect of said external pressures on said piston through said plunger extension first mentioned to insure normal operation irrespective of surrounding pressures on the cylinder.

11. A structure as claimed in claim 9, a cylinder formed in said plunger extension and a plunger in said cylinder; a spring depressing said plunger; said hoisting cable cooperating directly with said plunger; and means cooperating with said plunger controlling said prime mover for operation only when said plunger is depressed, and for locking said prime mover against operation when said plunger is raised through the efkfort of said cable to Vhoist the dredge.

operation; a bail for said dredge; control means associated Withrsaid bail and with said hoisting cable, and including, prime mover control means opening said operating valve when saidcable is slack and closing said valve when said cable is supporting said dredge, and, release means opening both of said release valves to pressure-balance said piston for idle movement to permit said counterweights to open said bucket when said hoisting cable is subjected to abnormal hoisting stress, to release said bucket from a relatively immovable obj ect.

13. A structure as claimed in claim 12; said release means maintaining said release valves open While the dredge is supported by said cable to drain the cylinder after removal from the surrounding uid, and closing said release Valves and resetting said release means for subsequent operation when'said dredge is rested on a support and the cable is slacked.

JOHN C. WILLIAMS.

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