US3726426A

US3726426A - Means for cranes

Info

Publication number: US3726426A
Application number: US00186220A
Authority: US
Inventors: L Tingskog
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1968-10-09
Filing date: 1971-10-04
Publication date: 1973-04-10
Anticipated expiration: 1990-04-10
Also published as: JPS4838807B1; DE1950494C3; DE1950494A1; DE1950494B2; GB1277070A

Abstract

A crane includes two gripping members or spreaders mounted adjacent to each other for raising and lowering movement by cables and for horizontal movement between a dock and a ship having compartments for receiving loads. The gripping members are provided with a magnetic or similar arrangement by which they can be coupled together or de-coupled from each other. The upward and downward movement of the gripping members when they are above the ship compartments is controlled by a memory device. During upward movement, when the gripping members reach a certain position when they are outside the compartments (cell construction) the magnetic or similar arrangement is energized and the gripping devices (spreaders) are coupled together. Thereafter the gripping devices are moved away for loading or unloading purposes. This upward movement is stored in the memory device to a certain point. When the loaded gripping members are moved downward, the memory device causes them to be uncoupled at a certain distance above the compartments and thereafter to stop within the compartments at substantially the same level from which they had previously started. The arrangement may also be such that the gripping devices can start at different levels, will move to the same level, be thereby coupled together, and on the downward movement will each stop at substantially the same position from which it started previously. This requires the use of one, preferably two memory devices, one for each gripping member.

Description

United States Patent 1 [111 3,726,426

Tingskog y [4 1 Apr. 10, 1973 [54] MEANS FOR CRANES [57] ABSTRACT [75] Inventor: henna Tingslmg Raai Sweden A crane includes two gripping members or spreaders 73 Assignee; Au Svenska Elektriska mounted adjacent to each other for raising and lowertiebolaget, Vasteras, Sweden ing movement by cables and for horizontal movement between a dock and a ship having compartments for ,[22] Flled' 1971 receiving loads. The gripping members are provided [21] Appl. No.: 186,220 I with a magnetic or similar arrangement by which they I can be coupled together or de-coupled from each Related Apphcatmn Data other. The upward and downward movement of the [63] Continuation-impart of Ser. No. 863,440, Oct. 3, gripping members when they are above the ship com- 1969, abandofledpartrnents is controlled by a memory device. During 0 upward movement, when the gripping members reach [30] Forelgn Apphcauon Pmnty a certain position when they are outside the compart- Oct. 9, 1968 Sweden ..13639/68 merits (Cell construction) the magnetic Or Similar m ,7 rangement is energized and the gripping devices 52 US. Cl. ..214/658, 214/15 R, 294/67 DA (Spreaders) are Coupled togethef- Thereafter the 51 Int. Cl. ..l ..;..B63b 27/00 gripping devices are moved away for loading or [58] Field of Search ..214/1 B, 14, 15 R, loading Purposes. This upward movement is stored in 2l4/658;2l2/86, 39, 132; 294/672, 67.4, 67 the memory device to a r in point. When the DA, 67,4 B loaded gripping members are moved downward, the 1 memory device causes them to be uncoupled at a cer 5 V V n f Cited tain distance above the compartments and thereafter to stop within the compartments at substantially the UNITED STATES PATENTS v same level from which they had previously started.

2,988,237 DFVOI ..214/11 R The arrangement may also be such that the 3,107,796 10/1963 Elsele ..214 15 R devices can Start at different lcvels will move to the same level, be thereby coupled together, and on the downward movement will each stop at substantially the same position from which it started previously. This requires the use of one, preferably two memory devices, one for each gripping member.

5 Claims, 11 Drawing Figures Primary Examiner-Drayton E. Hoffman Assistant Examiner-George F. Abraham Attorney-Jennings Bailey, Jr.

PATENTED B 3,726,426

7 sum 2 or 4 I v v INVENTOR LENA/A7197 77/va5m96,

BY, I. fkm ATTORNEY I v PATENTEDAPR 1 OIHYS SHEET ,3 0F 4 INVENTOR 4 [IV/V4197 wuss/roe,

r A ORNEY PAIENIED B 3.726.426

saw u 0F 4 I NVET\TOR BY A 0R EY 1 MEANS FOR CRANES RELATED APPLICATION This application is a continuation in part of application Ser. No. 863,440, filed Oct. 3, 1969, and now abandoned.

BACKGROUND OF THE INVENTION l. Field of the Invention The invention relates to control mechanism for cranes for loading objects from a dock to compartments in a ship or the like.

2. The Prior Art A ship which is being loaded or unloaded moves somewhat during the operation. When containers or the like are being loaded or unloaded the speed of the gripping device with the goods is decreased at a certain height and completely stopped in the final stage. This is often done manually by an operator, which may be tiring and not very reliable, not least because of the difficulty of observing the container on its way in and out of a compartment system which is normally arranged on ships for container loading, and so on. Another difficulty is alterations inthe position of the ship during the loading and unloading, for example caused by the altering load of cargo, alterations in water level, small changes in position in relation to the quay, and other factors. Various mechanical sensing and guiding members have been tried in order to solve this problem, but this has caused certain disadvantages in the form of expensive and complicated equipment.

SUMMARY OF THE INVENTION The invention aims at solving these general problems and is characterized in that it comprises at least one pulse generator or analogue transmitter intended to emit pulses to at least one memory device when the gripping devices (Spreaders) release goods and/or when the gripping devices leave the compartment construction so that the output signal or signals of the memory function or functions are sensed in measuring devices to retard and stop the gripping devices and/or connect or in reverse direction disconnect these gripping devices upon certain output signals for the memory or memories concerning the position of the load and the position of the compartment construction during the previous operation of the gripping means. Such a device permits a high degree of automatized loading or unloading even during considerable alterations in the position of the ship during the operation.

In a preferred embodiment only one memory and a generator are used connected to the lifting machinery of one of the gripping devices. The other gripping device is then always regulated at the same height when the two devices are operating together.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 shows in side elevation a gripping arrangement for a part of an adjacent gripping arrangement;

FIG. 2 is a top plan view of the connection arrangement between two gripping arrangements;

FIGS. 3 and 4 are circuit diagrams;

FIG. 5 shows the relationship between the gripping arrangements and the compartments on a ship;

FIGS. 5A and 5B are cross-sections on the lines A- A and B-B respectively of FIG. 5;

FIG. 5C is a view similar to FIG. 5 at right angles thereto;

FIG. 5D shows in perspective a pair of coupled gripping members;

FIG. 6 shows a modification in which the gripping devices can start their movement at different levels;

FIG. 6A is a view of a modification of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a gripping device 9 which is connected by means of a number of cables to a crane and is intended, for example, for container loading. The pulley wheels are shown (without cables) at 10 and in each corner of the gripping device is a gripping member 31, suitably four members per gripping device which in this case are shaped to fit into an oblong opening in the container to be loaded and are then turned Guiding arms 11, 12 are also arranged on the gripping device. These are not for use in connection with operation in a compartment construction, but only when gripping freely placed containers and they can be pivoted by the operator. The gripping device can be connected to an adjacent gripping device 13 in order to increase the stability in positions above the compartment construction of a ship for container loading, car transport, or the like. The connection 14, which is shown in more detail in FIG. 2, may be of electromagnetic type (see electromagnets at 15 and 16) and can I thus be rapidly released by the operator or automatically according to the invention. They are drawn back when the load is released before movement down into the ship compartment in order to expose the space A. Here the ship has transverse connections, the uppermost placed immediately below the deck 8 is an inductive emitter for sensing the steel walls in the compartment.

In order to connect the two adjacent gripping devices, the magnets 15 and 16 are mounted on bars 17 slidably guided in brackets 18 secured to the gripping devices and urged inwardly or away from each other by double acting hydraulic cylinders 19 or spring members. The electromagnets have a sufficient strength so that, when they are energized, they will hold the connecting devices together after being brought together by the cylinders 19 which will move the device sufficiently to allow each gripping device to enter one of the compartments of a ship which is being loaded.

Referring to FIG. 5, three compartments a, b and c of a ship are shown being loaded, for example. In compartments a and b containers or other packages previously introduced are at the same height.

In the righthand compartment, as will be explained below, the containers do not stand at the same height.

The gripping devices are only diagrammatically shown in FIG. 5. The lifting cables are indicated at 20 and pass over pulleys 21. Adjacent the path of upward movement of the gripping devices is an inductive emitter (8), acting as a microswitch, slightly above the point of exit of the gripping devices from the compartments, which emitter shows the presence of steel in the compartment, thus giving a signal when the spreaders leave or arrive at this point. This starts the counting upwards, which will stop at a certain height above 8. The counting may also be stopped by some sensing device, such as a photocell 24.

Referring now to FIG. 3, emitter controlled microswitches 22 and 23

control switches

27, 28 and 29, 30 respectively.

Switches

27 and 29 are connected in circuit with the magnets 15, 16.

Switches

8 and 30 are connected to lifting motors 31 and 32 respectively. (In a simple embodiment one emitter 8 may control both the gripping devices in a pair.)

Connected in series to the switch 29 and the magnets l5, 16 is a relay 33 which can operate switches 34, 35 which are arranged in series with the

motors

32, 32 bypassing the switches 28, 30, respectively, and relay 32 also controls a switch 36 which in series with a second switch 37 constitutes a holding circuit for the magnets 15, 16. Also in series with motors31, 32 are

switches

38 and 39 respectively.

Referring now to FIG. 4, one of the pulleys 21 has connected with it a disc 40 with a plurality of holes 41 arranged therein and passing through a photoelectric cell 42 and a source of light 43. Photoelectric cell 42 is connected to a memory device 43 through a switch 44. Switch 44 is controlled by photoelectric cell 24 through a flip-flop circuit 45 which serves to open and close the switch 44 alternately when the photocell is deenergized, or by means of a programming device 24, started by the emitter 8.

The memory, 43 is connected by a series of resistances 46, 47, 48 and 49 to a resistance 50 which is in parallel with relays 51 and 52. Relay 51 when energized operates to open switch 37, while relay 52 when energized operates to open

switches

38 and 39.

Memory 43 may for example be of the type shown in Stendahl application ,Ser. no. 423,999 or in British patent no. 1,086,242, which will count upwardly as the successive pulses are received upon rotation of wheel 40 in one direction and downwardly upon rotation of the wheel in the other direction. Each pulse will cause the resistances 46 to 49 to be successively connected or disconnected by meansof bi-stable flip-flop devices. In other words, the first pulse connects the resistance 46, thesecond disconnects 46 and connects 47; the third connects both '46 and 47; the fourthconnects 48 and disconnects 46 and 47, and so on, so that the total re-' sistance in the circuit is dependent-upon the number of pulses.

, Assuming that the gripping devices have just released a pair of loads in adjacent compartments, the operator operates a manual control to energize the motors 31 and 32 to raise the gripping devices to the same level. Switch 44 is closed. As the gripping members are raised the distance is measured by the number of pulses fed t the memory 18.

When the gripping members have reached a certain level above the compartments, they actuate emitters or microswitches 22 and 23 which close switches 27 and 29 energizing relay 33. At the same time switches 28 and 30 are opened and the supply of current to the motors 32 is momentarily stopped if they are not at the same level, if stopping is not actuated. Closing of

switches

27 and 29 energizes magnets and 16, and thus couples together the two carriers or gripping devices as soon as both of them have reached the positions opposite the microswitches.

Energization of relay 33 also closes the switches 34, 35 to motors 31, 32 so that these start up again and raise the gripping devices. As soon as the emitter or microswitches 22 and 23 have been cleared, motors 31 and 32 will again receive current through

switches

38 and 30. This continues until the gripping members have reached a predetermined upward position, in which limit switches 26 act to stop the counting and/or possibly to deenergize the motors 31 and 32.

Closing of relay 33 also closes a holding circuit through the magnets 14, 15 with

switches

36 and 37. The gripping devices are now moved by the mechanism 10 to the desired point on the dock, where they are positioned to pick up further containers or load objects. They are now returned to a position above the compartments, and the motors 31 and 32 are reversed to lower the load objects toward the compartments.

During this lowering action, the counter 18 counts backwards, starting as soon as the lowering begins. After a certain countdown, the relay 51 is energized and opens switch 37 in the holding circuit of magnets 15, 16 so that the connection between the two gripping devices is released and they are in a condition in which they can go into the different compartments. The motors 31, 32 continue to lower the loads into the compartments. When the counter 18 reaches zero, which means that the load articles are resting on the previously released articles, relay 52 is operated and opens the motor circuit, thus stopping the motors 31 and 32.

While there might be slight over-travel when the motors lower the gripping devices, because of the difference in position of successive packages, this is allowed for by the slack in the cable. Likewise, adjustment of the resistance of the relays can be made to compensate for this slight difference. Because of such slack, the pulley 21 and the disc 22 which is connected to it will not begin to turn on the return movement of the cable until it is taut and begins to lift the gripping devices.

8 FIG. 6 shows an arrangement which can allow for the fact that the packages or containers in the different compartments are at a different level, as for example in compartments b and c of FIG. 5.

The circuitry is the same as in FIGS. 3 and 4, except that the cables pass over pulleys'21av and 21b, connected to discs 40a and 40b respectively and each provided with a series of holes, which pass between photoelectric cells 420 and 42b and

lamps

43a, 43b. These feed pulses to memories43a and 43b respectively, which couple in resistances 46a to 49a and 46b to 49b respectively. Memory 43a controls relay 51, for opening switch 37 during the downward movement of the gripping devices, and relay 52a which opens switch 38. Memory 43b controls relay 52b which opens switch Photocell 24 or programming device 24 controls members 45a and 45b which in turn control switches 44a and 44b.

Assuming that the containers being loaded are at different levels, the disc 40a will turn during the raising of the gripping members through a different angle from 40b, and will therefore provide a different number of pulses to memory devices 43a from those supplied to 43b. The switches 44a and 44b are opened at the same time, because at this time the gripping devices are moving together. 1

During the downward movement, when the photocell etc. 24 closes the circuit to both memory devices, the two memory devices will start to count, but memory device 43b will reach zero before memory 43a, and will therefore open the switch 39 before the switch 38 is opened, thus stopping the gripping devices at the proper levels. Relay 51 will deenergize the magnets at a certain point in the downward movement before the gripping devices reach the upper edges of the compartments. The back counting is often started at a height sensed in the device without any special sensing.

Thus the start of the next operating cycle the counter is set at zero and thus also the memory and new suitable retarding and stopping points are calculated, which need not be identical to the previous ones due to altered position of the ship and a higher level desired for the next container. The pulse. emitter is designed so that the pulse frequency has a certain simple relationship with the height of the container and it must be possible in the memory to change over for certain pulse additionsor subtractions according to whether it is loading or unloading which is being carried out.

The second memory 43b, which may be common for the pair of gripping devices, senses the height above the compartment construction and thus a suitable position for attaching or discharging, but even here it may be a question of retarding at certain levelsabove and near the compartment construction.

In this case the switching voltage of the relays may be chosen for a suitable level for discharging (attaching) and for retarding. The pulse train to the memory is connected by means of the inductive emitter 8 (FIGS. 5, 6A) when a gripping device (or both gripping devices) leaves the compartment construction and the height of the gripping device above the compartment construction is thus stored in the memory 43b in the form of a certain pulse number. At the next loading operation impulses are emitted for retarding/discharging, and so on at the levels sensed from the memory and a new signal is stored in the memory next time the pair of gripping devices leaves the compartment construction. The considerably improved possibilities of automatic control of the gripping devices offered by the invention are immediately understood.

The memory and pulse emitter may also be designed in other ways known within the data field, and in more simple cases it is possible merely to permit the pulley wheel to drive a potentiometer arm on a potentiometer so that, for example, the output voltage can be set at zero at the starting impulse.

The number of connectible gripping devices (spreaders) may be more than two and it is also possible to use several gripping systems independent of each other.

The invention may have many alternative embodiments within the scope of the following claims.

I claim:

1. In combination with a crane having at least two gripping devices and means for moving the gripping devices between loading and unloading positions, connection means for connecting the gripping devices to and disconnecting them from each other, at least one memory device, at least one pulse generator means to furnish pulses to the memory device in response to movement of the gripping devices away from one of such dpositions, and means responsive to the (pulses store in such memory device and operable uring return of the gripping devices to such position to control the connection means.

2. In combination with a crane having at least two gripping devices and means for moving the gripping devices between loading and unloading positions, connection means for connecting the gripping devices to and disconnecting them from each other, at least one pulse generating means to furnish pulses to the memory devices in response to movement of the gripping devices away from one of such positions, means responsive to movement of the gripping devices away from such position to actuate said connection means to connect the gripping devices to each other, means responsive to pulses stored in such memory devices and operable during return movement of the gripping devices towards such position, to actuate said connection means to disconnect the gripping devices from each other and thereafter to stop such return movement at substantially the same points from which the gripping devices started.

3. In combination with a crane as claimed in claim 2, means controlled by movement of the gripping devices to a predetermined point away from such position to disconnect the memory device from the pulse furnishing means and means responsive to return movement past such predetermined point to reconnect the memory device to the pulse furnishing means.

4. In a combination as claimed in claim 3, in which said pulse furnishing means comprises a rotatable member, said memory device including means responsive to rotation of said member in one direction to increase the setting thereof and means responsive to rotation of the member in the other .direction to decrease the setting thereof.

5. In a combination with a crane as claimed in claim 2, a memory device and a pulse generating means therefor associated with each of said gripping devices, and said means for stopping the return movement including a separate means for each of said gripping devices responsive to the setting of the memory devices associated therewith.

Claims

1. In combination with a crane having at least two gripping devices and means for moving the gripping devices between loading and unloading positions, connection means for connecting the gripping devices to and disconnecting them from each other, at least one memory device, at least one pulse generator means to furnish pulses to the memory device in response to movement of the gripping devices away from one of such positions, and means responsive to the pulses stored in such memory device and operable during return of the gripping devices to such position to control the connection means.

4. In a combination as claimed in claim 3, in which said pulse furnishing means comprises a rotatable member, said memory device including means responsive to rotation of said member in one direction to increase the setting thereof and means responsive to rotation of the member in the other direction to decrease the setting thereof.