Endless bucket dredge with articulated ladder and swell compensator

Claim 2

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper tumbler at the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, and a lower swingable ladder section having a clevised upper end with clevis arms supporting a shaft and pivoted thereby to the section above it at a lower end lying between the clevis arms, said lower ladder section having a lower tumbler at its lower extremity. a bucket-line guide roller supported by said shaft and thereby at the pivot line of the upper and lower swingable sections, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and meeting and leaving said bucket-line guide roller tangent thereto and supported by said ladder, said bucket-line guide roller and clevis structure enabling maximum downward swinging of said lower section relative to said upper section while maintaining the bucket line in proper alignment with said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 3

The dredge of claim 1 wherein there are at least three swingable sections successively pivoted to each other For relative swinging movement in a vertical plane only as well as being pivoted to said superstructure at the upper end of the upper section thereof, each pivoted connection having a clevis connection as recited with a bucket-line guide roller sup-ported on the pivot line thereof.

Claim 4

The dredge of claim 1 wherein the lower end of said swingable lower ladder section is suspended by two sets of block-and-tackle suspensions lying in the same plane but inclined to each other set at acute angles symmetrical about the center line of the dredge and of the multiple section ladder.

Claim 5

A floating deep-digging dredge, including in combination: a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper driving tumbler supported by said superstructure near the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, at a point below and near said upper tumbler a lower swingable ladder section pivoted to the section above it and having a lower tumbler at its lower extremity, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 6

A floating deep-digging dredge, including in combination: a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper driving tumbler supported by said superstructure near the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, at a point below and near said upper tumbler a lower swingable ladder section pivoted to the section above it and having a lower tumbler at its lower extremity, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 7

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper tumbler at the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, and a lower swingable ladder section pivoted to the section above it and having a lower tumbler at its lower extremity, said ladder having a fixed uppermost section, supported by said superstructure, said superstructure also supporting said upper tumbler, said upper swingable ladder section being pivoted on said superstructure below and independent from said fixed uppermost section, for swinging movement relative to said fixed section, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 8

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper tumbler at the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, and a lower swingable ladder section pivoted to the section above it and having a lower tumbler at its lower extremity, said ladder having a fixed uppermost section, supported by said superstructure, said superstructure also supporting said upper tumbler, said upper swingable ladder section being pivoted on said superstructure below and independent from said fixed uppermost section, for swinging movement relative to said fixed section, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 9

The dredge of claim 5 wherein said fixed uppermost ladder section is located and arranged to provide at all times a constant tangent alignment of the bucket line leading to the pitch circle of the upper tumbler and coaxial with a shaft which supports the upper tumbler.

Claim 10

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising two swingable ladder sections pivoted to each other for relative swinging movement in a vertical plane only and including an upper driving tumbler supported by the superstructure near and separate from the top of the ladder, the upper ladder section being pivoted at its upper end directly to said superstructure independently of the upper driving tumbler, and a lower swingable ladder section pivoted to said upper ladder section and having a lower tumbler at its lower extremity, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported bY said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 11

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising two swingable ladder sections pivoted to each other for relative swinging movement in a vertical plane only and including an upper driving tumbler supported by the superstructure near and separate from the top of the ladder, the upper ladder section being pivoted at its upper end directly to said superstructure independently of the upper driving tumbler, and a lower swingable ladder section pivoted to said upper ladder section and having a lower tumbler at its lower extremity, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported bY said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 12

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a fixed uppermost ladder section and at least one swingable ladder section pivoted at its upper end to said superstructure at an uppermost pivot for swinging movement relative to said fixed section in a vertical plane only, said uppermost pivot being supported independently of said fixed ladder section, an upper tumbler at the top of said ladder, a lower tumbler at the lower extremity of said ladder, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, at least one block-and-tackle suspension supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 13

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a fixed uppermost ladder section and at least one swingable ladder section pivoted at its upper end to said superstructure at an uppermost pivot for swinging movement relative to said fixed section in a vertical plane only, said uppermost pivot being supported independently of said fixed ladder section, an upper tumbler at the top of said ladder, a lower tumbler at the lower extremity of said ladder, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, at least one block-and-tackle suspension supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull.

Claim 14

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper tumbler at the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, and a lower swingable ladder section pivoted to the section above it and having a lower tumbler at its lower extremity, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, sounding means for determining instantaneously the height of the hull above the bottom of the water on which the hull is floating, depth signal means actuated by said sounding means, angle sensing means for determining, instantaneously the angle which the true horizontal makes with the nominally horizontal center line of said hull, angle signal means actuated by said angle sensing means, and control means receiving said depth signal and said angle signal means and controlling the suspension length of at least said lower ladder section and accommodating it to swells in the water level on which the hull floats.

Claim 15

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper tumbler at the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, and a lower swingable ladder section pivoted to the section above it and having a lower tumbler at its lower extremity, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, sounding means for determining instantaneously the height of the hull above the bottom of the water on which the hull is floating, depth signal means actuated by said sounding means, angle sensing means for determining, instantaneously the angle which the true horizontal makes with the nominally horizontal center line of said hull, angle signal means actuated by said angle sensing means, and control means receiving said depth signal and said angle signal means and controlling the suspension length of at least said lower ladder section and accommodating it to swells in the water level on which the hull floats.

Claim 16

The dredge of claim 9 having a headline extending from shore or sea bottom to said dredge, a headline winch for varying the length of said headline, and a control circuit actuated by said control means for controlling the instantaneous length of said headline during swells.

Claim 17

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper tumbler at the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, and a lower swingable ladder section pivoted to the section above it and having a lower tumbler at its lower extremity, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, sounding means for indicating instantaneously the height of the hull above the bottom of the water on which the hull is floating, a first command potentiometer actuated by said sounding means, angle sensing means for indicating instantaneously the angle which the true horizontal makes with the nominally horizontal center line of said hull, a second command potentiometer actuated by said angle sensing means, said winch means comprising a separate luffline winch for each said suspension, a headline extending from shore or sea bottom to said dredge, a headline winch for varying the length of said headline, a third command potentiometer for setting a nominal position of said headline winch, additional command potentiometers, one for setting a nominal position for each said luffline winch, and control means connected to all of said command potentiometers and transmitting the settings of said third and additional command potentiometers to their said winches by a series of outputs, said control means having means for superimposing on said outputs the effects of said first and second command potentiometers, so that the nominal positions of said headline winch and said luffline winches are kept changing to actual positions varying from said nominal positions by amounts such as are needed to keep the position of said lower tumbler substantially constant.

Claim 18

A floating deep-digging dredge, including in combination, a hull, superstructure supported on said hull, an articulated ladder comprising a plurality of sections pivoted together for relative swinging movement in a vertical plane only and including an upper tumbler at the top of the ladder, an upper swingable ladder section having a main pivot adjacent its upper end supported by said superstructure, and a lower swingable ladder section pivoted to the section above it and having a lower tumbler at its lower extremity, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, sounding means for indicating instantaneously the height of the hull above the bottom of the water on which the hull is floating, a first command potentiometer actuated by said sounding means, angle sensing means for indicating instantaneously the angle which the true horizontal makes with the nominally horizontal center line of said hull, a second command potentiometer actuated by said angle sensing means, said winch means comprising a separate luffline winch for each said suspension, a headline extending from shore or sea bottom to said dredge, a headline winch for varying the length of said headline, a third command potentiometer for setting a nominal position of said headline winch, additional command potentiometers, one for setting a nominal position for each said luffline winch, and control means connected to all of said command potentiometers and transmitting the settings of said third and additional command potentiometers to their said winches by a series of outputs, said control means having means for superimposing on said outputs the effects of said first and second command potentiometers, so that the nominal positions of said headline winch and said luffline winches are kept changing to actual positions varying from said nominal positions by amounts such as are needed to keep the position of said lower tumbler substantially constant.

Claim 19

The dredge of claim 11 wherein some of the lufflines have associated with them respective hydraulic cylinders and pistons, said pistons being connected to a translatable sheave, said control means also determining both a nominal position and actual positions for said piston, as determined by the superposition of the command signals.

Claim 20

The dredge of claim 12 having a feedback potentiometer for each winch and each hydraulic piston to provide a base signal at the nominal position thereof, said control means correcting said base signal by an error signal obtained from said first and second command potentiometers.

Claim 21

A floating deep-digging dredge having a hull and a superstructure with a ladder pivotally supported by said superstructure and a digging bucket line passing around an upper driving tumbler supported by the superstructure with the upper pivot for the ladder separately supported by the superstructure and a lower tumbler on the lower end of the ladder and supported by said ladder, characterized by the ladder comprising a plurality of articulated sections pivoted together for relative swinging movement in a vertical plane only, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull, the lower end of at least the lowermost ladder section being suspended by two sets of block-and-tackle suspensions lying in the same plane but inclined to each other set at acute angles symmetrical about the center line of the dredge and of the multiple section ladder.

Claim 22

A floating deep-digging dredge having a hull and a superstructure with a ladder pivotally supported by said superstructure and a digging bucket line passing around an upper driving tumbler supported by the superstructure with the upper pivot for the ladder separately supported by the superstructure and a lower tumbler on the lower end of the ladder and supported by said ladder, characterized by the ladder comprising a plurality of articulated sections pivoted together for relative swinging movement in a vertical plane only, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, and winch means for said cable supported by said hull, the lower end of at least the lowermost ladder section being suspended by two sets of block-and-tackle suspensions lying in the same plane but inclined to each other set at acute angles symmetrical about the center line of the dredge and of the multiple section ladder.

Claim 23

A floating deep-digging dredge having a hull and a superstructure with a ladder pivotally supported by said superstructure and a digging bucket line passing around an upper tumbler-coaxial with the pivot for the ladder and a lower tumbler on the lower end of the ladder and on both sides of said ladder and supported by said ladder, characterized by the ladder comprising a plurality of articulated sections pivoted together for relative swinging movement in a vertical plane only, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, sounding means for determining instantaneously the height of the hull above the bottom of the water on which the hull is floating, depth sigNal means actuated by said sounding means, angle sensing means for determining, instantaneously the angle which the true horizontal makes with the nominally horizontal center line of the hull, angle signal means actuated by said angle sensing means, and control means receiving said depth signal and said angle signal means and controlling the suspension length of at least said lower ladder section and accommodating it to swells in the water level on which the hull floats.

Claim 24

A floating deep-digging dredge having a hull and a superstructure with a ladder pivotally supported by said superstructure and a digging bucket line passing around an upper tumbler-coaxial with the pivot for the ladder and a lower tumbler on the lower end of the ladder and on both sides of said ladder and supported by said ladder, characterized by the ladder comprising a plurality of articulated sections pivoted together for relative swinging movement in a vertical plane only, a plurality of block-and-tackle suspensions supported by said superstructure, each suspension being connected to the lower end of a swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, sounding means for determining instantaneously the height of the hull above the bottom of the water on which the hull is floating, depth sigNal means actuated by said sounding means, angle sensing means for determining, instantaneously the angle which the true horizontal makes with the nominally horizontal center line of the hull, angle signal means actuated by said angle sensing means, and control means receiving said depth signal and said angle signal means and controlling the suspension length of at least said lower ladder section and accommodating it to swells in the water level on which the hull floats.

Claim 25

The dredge of claim 15 having a headline extending from shore or sea bottom to said dredge, a headline winch for varying the length of said headline, and means actuated by said control means for controlling the instantaneous length of said headline during swells.

Claim 26

A floating deep-digging dredge having a hull and superstructure supported thereon, including in combination an articulated ladder comprising a fixed uppermost section supported by said superstructure and at least one lower section pivotally supported by said superstructure below and independent from the lower end of said fixed section and in alignment therewith, for relative swinging movement in a vertical plane only, an upper tumbler supported by said superstructure at the top of the ladder, a lower tumbler at the lower extremity of said ladder supported by a said lower section, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, block-and-tackle suspension means supported by said superstructure and connected to the lower end of each said lower section for support thereof and having a cable, and winch means for each said cable, supported by said hull.

Claim 27

A floating deep-digging dredge having a hull and superstructure supported thereon, including in combination an articulated ladder comprising a fixed uppermost section supported by said superstructure and at least one lower section pivotally supported by said superstructure below and independent from the lower end of said fixed section and in alignment therewith, for relative swinging movement in a vertical plane only, an upper tumbler supported by said superstructure at the top of the ladder, a lower tumbler at the lower extremity of said ladder supported by a said lower section, a digging bucket line passing around both said upper and lower tumbler and on both sides of said ladder and supported by said ladder, block-and-tackle suspension means supported by said superstructure and connected to the lower end of each said lower section for support thereof and having a cable, and winch means for each said cable, supported by said hull.

Claim 28

The dredge of claim 17 in which there is a single swingable ladder section, carrying said lower tumbler.

Claim 29

The dredge of claim 17 wherein there are two swingable lower ladder sections pivoted to each other, the upper of these lower ladder sections being pivoted at its upper end to said superstructure.

Claim 30

The dredge of claim 17 wherein there are at least three swingable lower ladder sections successively pivoted to each other as well as being pivoted to said superstructure at the upper end of the upper section thereof.

Claim 31

A floating deep-digging dredge, including in combination with a hull and a superstructure supported thereon: a fixed uppermost ladder section supported by said superstructure, a swingable ladder portion pivoted at its upper end to said superstructure for relative swinging movement of said swingable ladder portion relative to said fixed ladder section in a vertical plane only, said pivot being supported independently of said fixed ladder section and offset from its axis, said swingable ladder portion comprising at least one ladder section and having an upper tumbler supported by said superstructure co-axial with the pivot of the swingable ladder portion and having a lower tumbler at its lower end, a continuous digging bucket line passing around both said upper and lower tumbler and on both sides of said swingable ladder portions and supported thereby, block-and-tackle suspension means supported by said superstructure and connected to the lower end of each section of said swingable ladder portion for support thereof, each unit thereof having a cable, winch means for said cable supported by said hull, a continuous transfer and delivery bucket line supported by said fixed uppermost ladder section, to which said digging bucket line transfers its load as it passes over said upper tumbler, and means for receiving the load from said transfer and delivery bucket line as it passes over the top of said fixed uppermost ladder section, at a constant angle.

Claim 32

A floating deep-digging dredge, including in combination with a hull and a superstructure supported thereon: a fixed uppermost ladder section supported by said superstructure, a swingable ladder portion pivoted at its upper end to said superstructure for relative swinging movement of said swingable ladder portion relative to said fixed ladder section in a vertical plane only, said pivot being supported independently of said fixed ladder section and offset from its axis, said swingable ladder portion comprising at least one ladder section and having an upper tumbler supported by said superstructure co-axial with the pivot of the swingable ladder portion and having a lower tumbler at its lower end, a continuous digging bucket line passing around both said upper and lower tumbler and on both sides of said swingable ladder portions and supported thereby, block-and-tackle suspension means supported by said superstructure and connected to the lower end of each section of said swingable ladder portion for support thereof, each unit thereof having a cable, winch means for said cable supported by said hull, a continuous transfer and delivery bucket line supported by said fixed uppermost ladder section, to which said digging bucket line transfers its load as it passes over said upper tumbler, and means for receiving the load from said transfer and delivery bucket line as it passes over the top of said fixed uppermost ladder section, at a constant angle.

Claim 33

The dredge of claim 21 wherein said means for receiving includes inclined grizzly bars and a secondary receiving chute.

Claim 34

The dredge of claim 21 wherein said swingable ladder portion comprises two sections pivoted to each other, the upper ladder section being the one pivoted at its upper end to said superstructure.

Claim 35

The dredge of claim 21 wherein said swingable ladder portion comprises three sections successively pivoted to each other as well as being pivoted to said superstructure at the upper end of the upper section thereof.

Claim 36

A floating deep-digging dredge having a hull and a superstructure with a ladder pivotally supported for relative swinging movement in a vertical plane only, by said hull and excavating means on the lower end of the ladder, characterized by block-and-tackle suspension means for the ladder supported by said superstructure and connected to the lower end of at least one swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, sounding means for determining instantaneously the height of the hull above the bottom of the water on which the hull is floating, depth signal means actuated by said sounding means, angle sensing means for determining, instantaneously the angle which the true horizontal makes with the nominally horizontal center line of said hull, angle signal means actuated by said angle sensing means, control means receiving said depth signal and said angle signal means and controlling the suspension lengths of said ladder and accommodating it to swells in the water level on which the hull floats.

Claim 37

A floating deep-digging dredge having a hull and a superstructure with a ladder pivotally supported for relative swinging movement in a vertical plane only, by said hull and excavating means on the lower end of the ladder, characterized by block-and-tackle suspension means for the ladder supported by said superstructure and connected to the lower end of at least one swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, sounding means for determining instantaneously the height of the hull above the bottom of the water on which the hull is floating, depth signal means actuated by said sounding means, angle sensing means for determining, instantaneously the angle which the true horizontal makes with the nominally horizontal center line of said hull, angle signal means actuated by said angle sensing means, control means receiving said depth signal and said angle signal means and controlling the suspension lengths of said ladder and accommodating it to swells in the water level on which the hull floats.

Claim 38

The dredge of claim 25 having a headline extending from shore or sea bottom to said dredge, a headline winch for varying the length of said headline, and a control circuit actuated by said control means for controlling the instantaneous length of said headline during swells.

Claim 39

The dredge of claim 25 wherein said depth signal means comprises a first command potentiometer actuated by said sounding means, and said angle signal means comprises a second command potentiometer actuated by said angle sensing means, said winch means comprising a separate luffline winch for each said suspension, a headline extending from shore or sea bottom to said dredge, a headline winch for varying the length of said headline, a third command potentiometer for setting a nominal position of said headline winch, additional command potentiometers, one for setting a nominal position for each said luffline winch, control means connected to all of said command potentiometers and transmitting the settings of said third and additional command potentiometers to their said winches by a series of outputs, said control means having means for superimposing on said outputs the effects of said first and second command potentiometers, so that the nominal positions of said headline winch and said luffline winches are kept changing to actual positions varying from said nominal positions by amounts such as are needed to keep the position of said excavating means substantially constant.

Claim 40

The dredge of claim 27 wherein some of the lufflines have associated with them respective hydraulic cylinders and pistons, said pistons being connected to a translatable sheave, said control means also determining both a nominal position and actual positions for said piston, as determined by the superposition of the command signals.

Claim 41

The dredge of claim 28 having a feedback potentiometer for each winch and each hydraulic piston to provide a base signal at the nominal position thereof, said control means correcting said base signal by an error signal obtained from said first and second command potentiometers.

Claim 42

A floating deep-digging dredge having a hull and a superstructure with a ladder pivotally supported for relative swinging movement in a vertical plane only, by said hull and excavating means on the lower end of the ladder, characterized by the ladder comprising a plurality of articulated sections pivoted together for swinging movement in said vertical plane, block-and-tackle suspension means for the ladder supported by saiD superstructure and connected to the lower end of at least one swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, means supported by said hull independently of said excavating means and connected to said winch means for rotation of said winch means for controlling the suspension lengths of said ladder, and means supported by said hull for moving said hull horizontally fore and aft in synchronization with said means for controlling the suspension lengths of said ladder, for accommodating said ladder vertically and horizontally to swells in the water level on which the hull floats to keep the position of said excavating means relative to the sea bottom and dredging face substantially constant.

Claim 43

A floating deep-digging dredge having a hull and a superstructure with a ladder pivotally supported for relative swinging movement in a vertical plane only, by said hull and excavating means on the lower end of the ladder, characterized by the ladder comprising a plurality of articulated sections pivoted together for swinging movement in said vertical plane, block-and-tackle suspension means for the ladder supported by saiD superstructure and connected to the lower end of at least one swingable ladder section for support thereof and having a cable, winch means for said cable supported by said hull, means supported by said hull independently of said excavating means and connected to said winch means for rotation of said winch means for controlling the suspension lengths of said ladder, and means supported by said hull for moving said hull horizontally fore and aft in synchronization with said means for controlling the suspension lengths of said ladder, for accommodating said ladder vertically and horizontally to swells in the water level on which the hull floats to keep the position of said excavating means relative to the sea bottom and dredging face substantially constant.