US3675794A

US3675794A - Winch arrangements

Info

Publication number: US3675794A
Application number: US138767A
Authority: US
Inventors: David John Ingram; Frederick James Maillardet
Original assignee: General Electric Co PLC
Current assignee: General Electric Co PLC
Priority date: 1971-04-29
Filing date: 1971-04-29
Publication date: 1972-07-11
Anticipated expiration: 1989-07-11

Abstract

A transfer arrangement for transferring articles between two relatively movable stations, such as ships at sea, in which a support cable carried by a winch on one of the stations and extending to a connecting member on the other station provides a support for the articles being transferred, wherein vertical oscillations of the load, resulting from relative movement of the stations, are damped by controlling the operation of the winch in response to control signals derived from variations in the distances between the stations and modified by further signals derived from variations in the tension in the support cable.

Description

0 United States Patent 1151 3,675,794

Ingram et al. [4 1 July 11, 1972 s41 WINCH ARRANGEMENTS 3,361,080 1/1968 Born et al. ..254/172 x [72] Inventors: David John Ingram, Bamhurst; Frederick FOREIGN PATENTS OR APPLICATIONS James Maillardet, Meopham, both of England 1,245,785 7/1967 Germany 254/ 172 [73] Assignee: The General Electric and English Electric Primary ExaminerGerald M. F nza Companies Unified, London, ng Assistant Examiner-Frank E. Werner [22] 16 Apr" 29 1971 Attorney-Kirschstein, Kirschstein, Ottinger & Frank 21 Appi. No.: 138,767 57] ABSTRACT A transfer arrangement for transferring articles between two 52 U.S.Cl .214 13,104/114,104/116, relatively movable stations, such as ships at in hi h a 254 172 support cable carried by a winch on one of the stations and ex- [51] Int. Cl ..B65g 67/58 tending to a connecting member on the station provides 58 Field of Search ..254/172;212/72;214/14,13; Suppofl for the articles being transferrednwherein vertical 104/112, 114 116 oscillations of the load, resulting from relative movement of the stations, are damped by controlling the operation of the 56 R I Cited winch in response to control signals derived from variations in 1 e erences the distances between the stations and modified by further UNITED STATES PATENTS signals derived from variations in the tension in the support cable. 2,443,028 6/1948 Edwards ..254/172 Butler et a1. ..254/l72 l2Claims,5DrawingFigures P'A'TENTEnJuL 1 1 1072 3. 675.79 4 SHEET 10F 3 INVENTORS DAVID JOHN INGRAM FREDERICK JAMES MAILLARDET P'A'TE'NTEDJULH m2 3,575,794

sum 2 BF 3 INVENTORS DAVID .J'OHN INGRAM FREDERICK JAMES HAILLARDET' 6 1-, W, hay/MM PKTENTED L 1 1 I972 SHEET 30F 3 1 2 P D1 1 2 V V 2 F 1 A A 4 m A B3 A M k k I C 00 M F .\s r R 2 J m l L 9 --1 E- b 2 FIIL 2 FiG.5.

WINCH ARRANGEMENTS CROSS REFERENCE TO A RELATED APPLICATION This application is a continuation of copending application Ser. No. 792,735, filed Jan. 2l, 1969, now abandoned for WINCH ARRANGEMENTS.

This invention relates to winch arrangements for use in transferring articles between two stations which are capable of moving relatively to each other during such transfer so as to vary their distance apart, and which arrangements are of the kind incorporating a support cable carried by a winch on one of the stations and arranged to extend to a connecting member on the other station to provide a support for the articles whilst they are being transferred.

Such arrangements have application, for example, in the trans-shipment of cargo and stores between two ships at sea, and hitherto the winch has usually been associated with control means designed to maintain a substantially constant tension in the support cable, thus permitting the cable to be paidout or hauled-in in dependence upon any variation in the distance between the ships. In practice, however, this distance usually varies in an oscillatory manner and the compensating effect of the control means is not sufficient to avoid a fluctuating tension in the support and the consequent vertical oscillation of the load, which in some cases can be considerable.

An object of the present invention is to provide an improved form of transfer arrangement by which this disadvantage is effectively reduced.

According to the invention a transfer arrangement of the kind referred to incorporates means for monitoring the distance between said stations, and for deriving therefrom variable control signals, means for modifying said control signals in response to variations in the tension of the support cable, and means for controlling the effective length of the support cable in response to said modified control signals so as to effect a damping of tension oscillations produced in the support cable due to a relative oscillatory movement of the two stations.

It has been found that by utilizing control signals which are a suitable function of the change in distance between the two stations, and modifying these in the appropriate sense by signals which vary with variations in the tension of the support cable, a high degree of damping of tension oscillations in the support cable can be achieved.

Any convenient method of monitoring the distance between the two stations may be employed but preferably there is provided a further cable, hereinafter referred to as the distance cable, carried by a winch drum on the first station and arranged to be attached to a connecting member on the other station, and means for maintaining a tension in the distance cable such that it extends substantially directly between the stations whereby any variation in the distance between the stations gives rise to an extension or reduction in the effective length of the distance cable. Preferably the control signals are generated in response to variations in the rate of change of the effective length of the distance cable, as determined, for example, by a tachometer associated with the winch drum carrying the distance cable, this introducing a measure of anticipation into the control of the paying out or hauling in of the support cable, which results in the suppression of violent load oscillations; however in some cases the control signals may be produced in response to changes in the effective length of the distance cable or to the acceleration of the cable as it is paidout or hauled in.

The invention may be applied to an arrangement utilizing a jack-stay designed to extend between the two stations for supporting the load during its transfer, and haulage winches on both of said stations for producing the traversal of the load, the jack-stay being carried by a winch drum on said one station, and the modified control signal being used either to control the winch drum directly, or to control other means such as a ram tensioner associated with the support cable, in such a manner as to effect the required damping of the tension oscillations.

Preferably, however, the support cable is in the form of a loop designed to extend between the two stations with the two sections of the loop each carried by a respective winch drum on said one of the station, the loop being arranged to pass around a pulley on the other station, and the load being arranged to be shared between the two loop sections, means also being provided for generating signals in response to the tension in each loop section for modifying said control signals, and the operation of both winch drums being controlled in response to the modified control signal.

Preferably one of the loop sections is fixed to a trolley designed to carry articles required to be transferred and supported by pulleys from the other loop section, so that movement of the trolley along the support cable can be effected by appropriate operation of the winch drums.

With such an arrangement all the power equipment associated with the support of the load and its traverse between the two stations may be located on one of the stations only. Such a support loop may therefore be used to advantage in transfer systems utilizing other means of controlling the tension in the cable.

The support cable winch drums are preferably operated hydraulically by means of variable delivery hydraulic pumps arranged to drive fixed displacement hydraulic motors coupled to the drums, control of the pumps conveniently being by means of electro-hydraulic servo-valves.

Preferably the tension in each section of the support cable loop is continuously monitored by means of tension sensors built into diverter pulleys, signals responsive to the varying tensions being fed into a control system and compared with a nominal tension signal to produce tension error signals which are used to modify the control signal, the modified control signal controlling the swash plate angles on the hydraulic pumps to determine the cable pay-out velocities of the winch drums.

Preferably means are also provided for controlling the load transfer velocity as the load being transferred approaches one or other of the stations. This can be achieved by arranging that only one or both of the support cable winch drums is controlled in response to said control signals in dependence upon the distance of a load being transferred from the station carrying the winch drums. For example the operation of the winch drums during a transfer operation is conveniently controlled in accordance with a transfer coefiicient which varies in dependence upon the length of cable paid out from the winch drum which is arranged to effect the hauling-in of the load, and two constants dependent upon the clearance distance from the first station within which the velocity of the load is required to be controlled relative to that station, and a transition distance over which the transition is made to the condition in which the velocity of the load is required to be controlled relative to the second station.

Thus the transfer coefficient can be used to govern automatically the relative winch pay-out rates, so that inside the clearance distance associated with the first station which carries the winch, variations in the motions of the two stations are accommodated by controlling the winch drum which effects the paying-out of the load. In the transition distance the load velocity will gradually change from being relative to the supply station to being relative to the receive station as the zone is traversed, and in the final condition variation in the motion of the stations will be accommodated by both winch drums equally.

The transition distance is a fixed distance chosen so that transition to the condition in which the load velocity is relative to the receive station is effected at a distance from the supply ship which is less than the normal minimum distance between the stations at which transfer of a load is normally carried out, and is unaffected with variation in the distance between the stations, this avoiding the necessity for having to generate a control function for the transition zone whose slope varies as the distance between the stations changes. However for some purposes the transition distance may be arranged to vary, the distance over which the load velocity is controlled relative to the receive station being fixed, the transfer coefficient in such a case being varied also in dependence upon the separation of the two stations.

In order that the invention may be readily understood, one transfer arrangement in accordance with the invention will now be described by way of example with reference to FIGS. 1 to of the accompanying schematic drawings, in which FIG. 1 illustrates the arrangement in diagrammatic form and not to scale, FIG. 2 represents the control system therefor and FIG. 3 a part of the control system also in diagrammatic form, FIG. 4 shows part of the arrangement in more detail, and FIG. 5 illustrates part of a modified arrangement.

Referring to the drawings, 1 and 2 are two ships between which articles are required to be transferred while the ships are travelling side-by-side on a substantially parallel course, the first ship 1 carrying a winch 3 having three

drums

4, 5, 6 designed to be operated by fixed displacement hydraulic motors M1, M2, M3 (FIG. 2) housed directly in the respective drums. The motors M1, M2 driving the

drums

4, 5, are powered by variable delivery pumps P1, P2, control of the latter being by means of electro-hydraulic servo valves V1, V2 designed to vary the swash plate angles of the pumps automatically in response to signals from control means C1, C2, the motor M3 being driven by a constant tension hydraulic power supply P3. The hydraulic pumps P1, P2, P3 are conveniently driven by a common electric motor E, and in addition each of the pumps is conveniently provided with a flywheel (not shown) for energy storage to compensate for any sudden load fluctuations, and to provide a degree of regeneration in known manner.

The lowest drum 4 carries one end of a loop 7 of cable, and loop passing around a pulley 8 on the other ship 2 and the opposite end being carried by the center winch drum 5. A trolley 9 for supporting a load required to be transferred is connected into the lower section 11 of the loop and carries pulleys 13 which rest on the top section 12 of the loop as shown, the trolley thus being supported by both sections of the loop of cable.

A further relatively light cable 16 carried by the upper winch drum 6 is connected to a fixed point on the second ship 2, the tension in this cable being maintained substantially constant so that it extends approximately directly between the two ships. A tachometer generator 19 and a revolution counter 20 are mounted so as to be responsive to the rotation of the drum 6 ,when the distance between the ships varies, the revolution counter providing an indication of the effective distance between the ships and the tachometer giving an indication of the instantaneous rate of change of this distance.

Signals from the tachometer 19, which comprises a pulse generator and pulse tachometer circuit, are used to control the swash plate angles on the hydraulic pumps controlling the operation of the

winch drums

4, 5, in such a manner that if unmodified the sum of the velocities with which the

ropes

11, 12, leave the

winch drums

4, 5, would be twice the velocity with which the rope 16 leaves the drum 6.

However, in addition the tensions in the upper and lower sections ll, 12, of the support cable are continuously monitored by means of

tension sensors

14, 15, associated with diverter pulleys l7, l8, and signals corresponding to these tensions are fed into a control system where they are compared with nominal tension signals to produce tension error signals, these latter being used to modify the signals that control the swash plate angles on the hydraulic pumps which determine the rope pay-out or haul-in velocities of the

winch drums

4, 5. The magnitudes of the tension error signals applied to the control signals are such as to cause the support cables to be paidout or hauled-in in dependence upon any change in the distance between the ships, but such that fluctuations in the tensions of the support cable are damped thereby reducing vertical oscillations of the load trolley.

A further revolution counter 21 is associated with the lower winch drum 4 to monitor the length of cable paid out from this winch drum.

In practice it is desirable for the load transfer velocity to be relative to the ship it is approaching or leaving. This is achieved by means of a transfer coefi'icient which controls the relative proportions of the ship separation velocity signal that are applied to the

winch drums

4, 5 during transfer of a load. Suitable functions of the transfer coefficient are generated in an automatic traverse control unit T using the length of cable paid out from cable drum 4, based upon signals from revolution counter 21, and two constants based upon clearance distance and transition distance required. Clearance distance" is the distance from the supply ship 1 within which the velocity of the load is required to be controlled relative to that ship, and "transition distance" is the distance over which the transition is made to the condition in which the velocity of the load is required to be controlled relative to the receive ship 2. The transition distance is chosen so that transition to the condition in which the velocity of the load is required to be con trolled relative to the receive ship is efi'ected at a distance from the supply ship which is less than the minimum distance between the ships at which transfer will normally be carried out.

The transfer coefiicient is arranged for example to be limited to a range between zero and one, being constant at the value 1 as the load commences to travel from the supply ship 1 until the clearance distance from that ship is reached; at this point it will start to decay until it reaches the value zero as the subsequent transition distance is completed; it will then remain at zero until the load reaches the receive ship 2. The transfer coefficient is used to govern the relative winch drum pay-out rate so that inside the supply ship clearance distance the load velocity is relative to the supply ship and relative motionsof the ship are accommodated by control of the winch drum 5. Beyond the transition zone the ship motions are accommodated by both

winch drums

4, 5 equally, so that the load transfer velocity is controlled relative to the receive ship, and in the transition zone between these two regions the load velocity gradually changes from being relative to the supply ship to being relative to the receive ship. The actual transfer velocity required can be set by manual control means MC.

In the control circuit illustrated diagrammatically in FIG. 2, the hydraulic and mechanical connections are represented by the arrowed solid lines and the signal paths by the arrowed broken lines. Part of the control circuit is illustrated in more detail in FIG. 3. In this figure signals from the tachometer 19, which consists of a pulse generator 191 and pulse tachometer circuit 192, are fed to a digital/analogue converter multiplier M. Also fed to the multiplier are signals derived from the revolution counter 21 associated with the lower winch drum 4 and modified to control the transfer velocity of the load in dependence upon its distance from the supply ship as previously explained, by the signal modifying circuit SM. The output of the multiplier M is fed to adder amplifier A3 where it is combined with a signal from the velocity control MC modified by circuit AR to give automatic acceleration and retardation of the load at the commencement and end of the transfer process. The combined signal is fed directly to an adjustable gain amplifier Al controlling via the servo valve V1 the swash plate angle of the pump P1, to which amplifier is also fed a tension setting signal from a tension setting device TS and a signal from the tension sensor 17 which varies with variations in the tension of the lower section 11 of the support cable loop.

The output of the adder amplifier is also applied in the reverse sense through an adder amplifier A4 to a further variable gain amplifier A2, signals from the tachometer 19 also being fed to the adder amplifier A4 as shown. Signals from the tension setting device TS and from the tension sensor 15 associated with the upper section 14 of the support cable loop are also applied to the variable gain amplifier A2 and the modified output from the latter controls the swash plate angle of the pump P2 via the servo valve V2.

The pulley on the receiving ship which carries the support cable loop is conveniently provided with a quick release mechanism 22 of any suitable form for enabling the loop to be freed quickly when required.

Pivoted catcher arms

31, 32 are associated with the ship 1, 2, for lowering the loads to the deck as indicated in FIG. 4 which illustrated part of the receive ship equipment, each having a forked end 33 for engagement with the trolley, and provided with releasable catch means 34 for securing the trolley to the respective catcher arm when the trolley has been winched into it. Hydraulic piston and cylinder units 35 are used to control the vertical pivoting movement of the arms. In operation the pivoted arms may be powered down regardless of cable tension by control of the hydraulic pressure to the piston and cylinder units. In a modification the hydraulic piston and cylinder unit controlling the pivoted catcher arm on the receive ship may be dispensed with and in such a case a dummy signal may be injected into the winch control system to cause the winches to pay out slightly when the trol ley has been engaged by the catcher arm, thus increasing the efiective sag in the cables and allowing the arm to descend.

Alternative means of maintaining the support cable pulley on to the receiving ship and of lowering the load can, however, be employed.

A modification of the arrangement described utilizes an alternative form of trolley. This is illustrated in FIG. 5 and comprises a pulley block 41, and a lifting block 42 to which a load lifting hook 43 is secured. The pulley block has two pulleys 44 which run on the top section 12 of the support cable loop, and a lower pulley 45. On the receiving ship side of the trolley the lower section 11 of the support cable loop is attached directly to the block 41, but on the supply ship side the lower section of the loop passes around the lower pulley 45 and a pulley 46 carried by the lifting block 42, before being attached to the pulley block.

During a transfer operation the tensions in the upper and lower section of the support cable loop are continuously monitored by the tension sensors 14, as previously described, the tension in the lower section 11 of the support cable being such that the lifting block 42 is held securely against the pulley block 41.

When the trolley reaches the receiving ship a clamping device (not shown) on the latter is operated to clamp the support cable to the pulley 8 and prevent rotation of the latter, control of the upper winch drum continuing to compensate for variations in the distance between the ships 1, 2, by paying out or hauling in the respective section of cable as appropriate. In addition the continued paying out of the lower section of cable when the trolley has reached this position results in a reduction in tension in this section of the cable and the lifting block 42 will then automatically be separated from the pulley block 41 resulting in the lowering of the load towards the deck. With such an arrangement the downward pivoting of the catcher arm 32 is not required.

The lifting book 43 is detachable and may be replaced by other devices such as a clamp for engaging different forms of load.

Although the arrangement above described is particularly applicable to the transfer of stores, weapons, palletized materials and the like between two ships, and permits the transfer of such articles to be carried out under much rougher conditions than hitherto considered practicable, an arrangement in accordance with the invention may also be used to support a refuelling line, for example between a tanker and a receiving ship. In such a case auxiliary trolleys will normally be provided for supporting intermediate parts of the refuelling line, these auxiliary trolleys also being carried by the support cable but not being connected thereto, and additional winches being provided for paying out the auxiliary trolleys the required distances depending upon the distance between the tanker and the receiving ship. In addition it will be appreciated that the system could also be used for transferring stores and other articles from a ship to a stationary point such as a lighthouse or lightship.

It will be understood that the invention can be applied to an arrangement utilizing a single jack-stay for supporting the trolley during its traversal between the two stations, together with a separate cable for producing the movement of the trolley across the jack-stay. In such an arrangement the tension in the jack-stay is conveniently controlled by control of the winch drum carrying it in response to control signals derived from a tachometer associated with a measuring cable to reduce fluctuations in the tension of the cable in a similar manner to the control of the winch drums of the arrangement previously described. In addition signals from a tension sensor associated with the jack-stay may be used to modify the control signals to further reduce tension oscillations as in the previous arrangement.

In a modification of this arrangement the modified control signals may be applied to other means for effecting the control of tension oscillations in the jack-stay, for example to a control unit for a ram-tensioner in the form of a hydraulic piston and cylinder assembly carrying pulleys around which the jackstay passes, such that movement of the piston effects the required control of the tension of the jack-stay.

Having thus described the invention, there is claimed as new and desired to be secured by Letters Patent:

1. A transfer arrangement for use in transferring articles between two stations which are spaced apart in a generally horizontal direction, and are capable of moving relatively to each other during such transfer so as to vary their distance apart, and which arrangement is of the kind incorporating a support cable carried by a winch on one of the stations and arranged to extend to a connecting member on the other station, and means for traversal of the articles across the support cable which thus provides a support for the articles while they are being transferred, said arrangement including:

a. means for monitoring the distance between said stations,

b. means for deriving variable control signals from said monitoring means, I

c. means for sensing variations in tension of the support cable,

d. means for modifying said control signals in response to said sensing means, and

e. means for controlling the effective length of the support cable in response to said modified control signals so as to efiect a damping of tension oscillations produced in the support cable due to a relative oscillatory movement of the two stations.

2. A transfer arrangement according to claim 1 incorporating a jack-stay designed to extend between the two stations for supporting the load during its transfer, and haulage winches on both of said stations for producing the traversal of the load, a winch drum carrying the jack-stay on said one station and a winch control system operable in response to said modified control signals to effect the damping of the tension oscillatrons.

3. A transfer arrangement according to claim 1 incorporating a jack-stay designed to extend between the two stations for supporting the load during its transfer, and haulage winches on both of said stations for producing the traversal of the load, a winch drum carrying the jack-stay on said one station and a ram tensioner associated with the jack-stay and operable in response to said modified control signals to effect the damping of the tension oscillations.

4. A transfer arrangement for use in transferring articles between two stations which are spaced apart in a generally horizontal direction, and are capable of moving relatively to each other during such transfer so as to vary their distance apart, and which arrangement is of the kind including a support cable carried by a winch on one of the stations and arranged to extend to a connecting member on the other station, and means for traversal of the articles across the support cable which thus provides a support for the articles while they are being transferred, said arrangement including:

a. means for monitor-ing the distance between said stations,

b. means for generating from said monitoring means variable control signals in response to variations in the rate of change of the distance between the two stations,

c. means for sensing variations in the tension of the support cable,

d. means for modifying the control signals in response to the said sensing means, and

e. means for controlling the effective length of the support cable in response to said modified control signals so as to effect a damping of tension oscillations produced in the support cable due to a relatively oscillatory movement of the two stations.

5. A transfer arrangement for use in transferring articles between two stations which are spaced apart in a generally horizontal direction and are capable of moving relatively to each other during such transfer so as to vary their distance apart, and which arrangement is of the kind including a support cable carried by a winch drum on one of the stations and arranged to extend to a connecting member on the other station, and means for traversal of the articles across the support cable which thus provides a support for the articles while they are being transferred, said arrangement including:

a. means for monitoring the distance between said stations,

b. monitoring means including a distance cable carried by a winch drum on said one station and capable of attachment to a connecting member on the other stations,

c. means for maintaining a tension in the distance cable such that it extends substantially directly between the stations whereby any variation in the distance between the stations gives rise to an extension or reduction in the effective length of the distance cable,

d. means for generating variable control signals in response to variations in the rate of change of the effective length of the distance cable,

e. means for generating mmodifying signals responsive to variations in the tension in the support cable,

f. means for combining said control and modifying signals in the appropriate sense to produce modified control signals, and

g. means for controlling the effective length of the support cable in response to said modified control signals so as to effect a damping of tension oscillations produced in the support cable due to a relatively oscillatory movement of the two stations.

6. A transfer arrangement for use in transferring articles between two stations which are spaced apart in a generally horizontal direction, and which are capable of moving relatively to each other during such transfer so as to vary their distance apart, and which arrangement is of the kind including a support cable in the form of a loop designed to extend between the two stations, with each of the two sections of the loop being carried by a respective winch drum on said one station and with the loop being arranged to pass around a pulley on the other station, the two loop sections sharing the load between them, said arrangement including:

a. means for monitoring the distance between said stations,

b. means generating from said monitoring means variable control signals in response to variations in the rate of change of the distance between the two stations,

c. means for sensing variations in the tension of the support cable, d. means for modifying the control signals in response to the said sensing means, and e. winch control systems associated with the respective winch drums each of which is operable in response to a said modified control signal in a manner which effects the damping of tension oscillations, produced in the support cable due to a relatively oscillatory movement of the two stations. 7. A transfer arrangement according to claim 6, wherein one of the loop sections is fixed to a trolley designed to carry articles required to be transferred and the trolley is supported by pulle from the other loop section, so that movement of the tro ey along the support cable can be effected by appropriate operation of the winch drums.

8. A transfer arrangement according to claim 7, wherein the trolley supports a carrier member having means for engaging and supporting articles to be transferred and held in a fixed relationship with the trolley by the tension in said one of the cable loop sections during the passage of the trolley between the stations, but such that paying out of the cable from the respective winch drum to reduce said tension when the trolley is at the opposite station results in the lowering of the carrier member with respect to the trolley.

9. A transfer arrangement according to claim 6 incorporating fixed displacement hydraulic motors coupled to the winch drums, variable delivery hydraulic pumps for driving the hydraulic motors, and electro-hydraulic servo-valves controlling said hydraulic pumps and operable in response to variations in said modified control signals.

10. A transfer arrangement according to claim 9 including tension sensors associated with a pair of diverter pulleys around each of which a respective one of the two loop sections of the support cable passes, and which are arranged to produce signals dependent upon the tensions in said sections, a comparison circuit for comparing said signals with nominal tension signals to produce tension error signals and means for modifying said control signals in response to changes in said tension error signals to produce a modified control signal for controlling the output of the hydraulic pumps.

11. A transfer arrangement according to claim 6 including means for controlling the load transfer velocity as the load being transferred approaches one or other of the stations.

12. A transfer arrangement according to claim 11, wherein the means for controlling the load transfer velocity governs automatically the relative winch drum pay-out rates in dependence upon the distance of the load from the two stations in a manner such that inside a predetermined clearance distance from one station variations in the motions of the two stations are accommodated by controlling the winch drum which effects the traversal of the load from that station, within a predetermined clearance distance from the other station variations in the motion of the stations are accommodated by both winch drums equally so that the load velocity is controlled relative to said other station, and within a transition distance between the two clearance distances the load velocity changes gradually from being relative to the supply station to being relative to the receive station as this transition distance is traversed.

Claims

1. A transfer arrangement for use in transferring articles between two stations which are spaced apart in a generally horizontal direction, and are capable of moving relatively to each other during such trAnsfer so as to vary their distance apart, and which arrangement is of the kind incorporating a support cable carried by a winch on one of the stations and arranged to extend to a connecting member on the other station, and means for traversal of the articles across the support cable which thus provides a support for the articles while they are being transferred, said arrangement including: a. means for monitoring the distance between said stations, b. means for deriving variable control signals from said monitoring means, c. means for sensing variations in tension of the support cable, d. means for modifying said control signals in response to said sensing means, and e. means for controlling the effective length of the support cable in response to said modified control signals so as to effect a damping of tension oscillations produced in the support cable due to a relative oscillatory movement of the two stations.

2. A transfer arrangement according to claim 1 incorporating a jack-stay designed to extend between the two stations for supporting the load during its transfer, and haulage winches on both of said stations for producing the traversal of the load, a winch drum carrying the jack-stay on said one station and a winch control system operable in response to said modified control signals to effect the damping of the tension oscillations.

4. A transfer arrangement for use in transferring articles between two stations which are spaced apart in a generally horizontal direction, and are capable of moving relatively to each other during such transfer so as to vary their distance apart, and which arrangement is of the kind including a support cable carried by a winch on one of the stations and arranged to extend to a connecting member on the other station, and means for traversal of the articles across the support cable which thus provides a support for the articles while they are being transferred, said arrangement including: a. means for monitoring the distance between said stations, b. means for generating from said monitoring means variable control signals in response to variations in the rate of change of the distance between the two stations, c. means for sensing variations in the tension of the support cable, d. means for modifying the control signals in response to the said sensing means, and e. means for controlling the effective length of the support cable in response to said modified control signals so as to effect a damping of tension oscillations produced in the support cable due to a relatively oscillatory movement of the two stations.

5. A transfer arrangement for use in transferring articles between two stations which are spaced apart in a generally horizontal direction and are capable of moving relatively to each other during such transfer so as to vary their distance apart, and which arrangement is of the kind including a support cable carried by a winch drum on one of the stations and arranged to extend to a connecting member on the other station, and means for traversal of the articles across the support cable which thus provides a support for the articles while they are being transferred, said arrangement including: a. means for monitoring the distance between said stations, b. monitoring means including a distance cable carried by a winch drum on said one station and capable of attachment to a connecting member on the other stations, c. means for maintaining a tension in the distance cable such that it extends substantially directly betwEen the stations whereby any variation in the distance between the stations gives rise to an extension or reduction in the effective length of the distance cable, d. means for generating variable control signals in response to variations in the rate of change of the effective length of the distance cable, e. means for generating modifying signals responsive to variations in the tension in the support cable, f. means for combining said control and modifying signals in the appropriate sense to produce modified control signals, and g. means for controlling the effective length of the support cable in response to said modified control signals so as to effect a damping of tension oscillations produced in the support cable due to a relatively oscillatory movement of the two stations.

6. A transfer arrangement for use in transferring articles between two stations which are spaced apart in a generally horizontal direction, and which are capable of moving relatively to each other during such transfer so as to vary their distance apart, and which arrangement is of the kind including a support cable in the form of a loop designed to extend between the two stations, with each of the two sections of the loop being carried by a respective winch drum on said one station and with the loop being arranged to pass around a pulley on the other station, the two loop sections sharing the load between them, said arrangement including: a. means for monitoring the distance between said stations, b. means generating from said monitoring means variable control signals in response to variations in the rate of change of the distance between the two stations, c. means for sensing variations in the tension of the support cable, d. means for modifying the control signals in response to the said sensing means, and e. winch control systems associated with the respective winch drums each of which is operable in response to a said modified control signal in a manner which effects the damping of tension oscillations, produced in the support cable due to a relatively oscillatory movement of the two stations.

7. A transfer arrangement according to claim 6, wherein one of the loop sections is fixed to a trolley designed to carry articles required to be transferred and the trolley is supported by pulleys from the other loop section, so that movement of the trolley along the support cable can be effected by appropriate operation of the winch drums.