Spreader List, Trim And Skew Adjustment Means

Abstract

A spreader list, trim, and skew adjustment system for a variable centers rope suspension system used on a gantry crane including individual rope operating means located at the outer end of the boom of the crane connected to the load and sway-stop lines to permit adjustment of the lines.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is an improvement of the Variable Centers Rope Suspension System disclosed in applicant's copending application Ser. No. 77,584, filed Oct. 2, 1970, now abandoned.

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention relates to a variable centers rope suspension system for a gantry crane and in particular to a system for aligning containers held by a spreader suspended from the rope system, with the container guides disposed on a ship.

2. DESCRIPTION OF THE PRIOR ART

The method and device set forth in U.S. patent application Ser. No. 77,584 is for the purpose of inhibiting or arresting the sway or pendulum motion of suspended loads in all directions of motion, both forward and backward with respect to the crane, and rotational sway about a vertical axis. However, the device of the referenced application does not disclose the details of the system whereby cargo containers moved between a level dockside and a listing or out of trim ship may be aligned with the guides of a shipboard container cell while the container is suspended from the crane.

A problem associated with the loading of cargo containers onto a ship by large cranes is misalignment of the load with the container stacking guides mounted on the ship due to listing or improper trim of the ship at dockside as the ship is being loaded.

SUMMARY OF THE INVENTION

The present invention is an improvement in a crane reeving system and is an adjustment means for the wire ropes of a spreader suspension system for an overhead traveling crane. The adjustment means includes mechanical linkages secured to each of the ropes which are reeved through sheeve blocks disposed at the sides of the spreader, and means are provided for moving each of the linkages whereby the list, trim, and skew of the supported spreader may be separately or simultaneously adjusted by moving one or more of said linkages.

The invention also contemplates a method of aligning a load suspended from a gantry crane. It includes attaching mechanical linkages to the wire ropes and actuating the linkages to move the ropes, without moving the wire rope drums, to adjust the list, trim, and skew of the load.

OBJECTS OF THE INVENTION

It is therefore an important object of the present invention to provide an adjustment means for either a standard or a variable centers rope suspension system to adjust the list, trim, and skew of a suspended load.

It is another object of the present invention to provide list, trim, and skew means which is integral with the suspension system supporting a cargo container lifting spreader and does not require additional ropes to be attached to the load.

It is a further object of the present invention to provide a list, trim, and skew adjustment means for a crane which is operable independently of the lifting and lowering of the load by the wire rope drums.

And it is yet a further object of the present invention to provide list, trim, and skew adjustment means for a crane which can be operated concurrently with the lifting or lowering of the load by the wire rope drums.

DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become apparent when the spreader list, trim and skew adjustment means is considered in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic of the reeving of a pair of trolleys suspending a lifting spreader including Jactuators mounted on the end of the gantry to adjust the reeving in accordance with the present invention:

FIG. 2 is an enlarged plan view of the reeving of FIG. 1 showing the connection to the Jactuators in greater detail;

FIG. 3 is a plan view of the trolleys showing the physical layout of the wire rope sheaves; and

FIG. 4 is a plan view of the headblock sheave arrangement.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference is made to the drawings for a description of the preferred embodiment of the invention wherein like reference numbers represent like elements on corresponding views.

The present invention is a list, trim, and skew adjustment means for a rope suspension system for an overhead traveling crane. FIG. 1 of the drawings shows a preferred embodiment of the suspension system utilized in a twin trolley system 11. It is obvious that the adjustment means could be used with a single trolley suspension system such as when the trolleys are disposed adjacent each other. Herein the description will describe the invention using a single trolley as well as two trolleys. Two trolleys are utilized to permit spreading apart of the suspension ropes on long lifts to inhibit and arrest sway of the load. In the actual embodiment, the two trolley sections are actually mounted on one trolley and reciprocate with respect to each other to effect the sway arresting action.

The wire rope hoist reeving system shown employs six parts of wire rope reeved through six sets of sheaves for supporting the load. Each of the trolleys has two pairs of sheaves mounted at opposite ends of the two trolleys and one pair of sheeves mounted at the edges removed from the adjacent trolley edges and, hereinafter called the removed edges.

The sheaves which support the spreader are mounted on a detachable headblock which permits quick change of lifting spreaders to permit different length spreaders to be attached to the headblock to handle different length cargo containers. The sheaves on the headblock include a pair at each end thereof and one at each side thereof.

The six parts of rope are actually portions of three wire ropes, connected together at their centers at the outboard end of the crane by mechanical linkages which are power driven ball screws, one type of which is commercially known as a Jactuator which is explained more clearly hereinafter. The active length of these three wire ropes remain essentially equal during load hoisting and lowering and inboard and outboard travel.

The wire rope system of FIG. 1 includes four suspension ropes 13A and B, 15A and B, which lift the ends of the spreader, and two sway arresting ropes 17A and B which engage the spreader at opposite sides thereof. For claim purposes, ropes 13A and 13B can be considered one rope, and ropes 15A and 15B another, and the sway arresting ropes 17A and 17B still another.

A first wire rope 13A, forming one-half of one of the suspension ropes, is reeved from a first wire rope drum 19, down from the machinery house to the crane gantry, and then outboard along the gantry and around a first set of sheaves disposed at the first ends of the trolley and spreader. The rope is reeved over a first sheave 21 of a first pair of sheaves 22 disposed on a first or left trolley 23. The rope is then reeved down to the lifting spreader headblock 25, which for all practical purposes can be considered the spreader, around a first load sheave 27 of a pair of sheaves 28 disposed at the first end of the spreader corresponding to the first end of the trolley, back up over the second trolley sheave 29 of the first pair of sheaves 22 disposed at the first end of the trolley. The rope is then run further outboard and secured to one end of a mechanical linkage of a first Jactuator 31 at the end of the gantry. The sheaves 21, 29 at the first end of the trolley form the first pair of sheaves 22 and, together with the corresponding headblock sheave 27, form a first set of sheaves.

A second wire rope 15A is reeved outboard, along the gantry from the same or first wire rope drum 19 and around a second set of sheaves disposed at the first ends of the trolley and spreader. The rope is reeved over a second trolley sheave 33 of a second pair of sheaves 34 disposed on the second trolley 35 at the first end thereof corresponding to the first end of the first trolley. The rope is then reeved down around the second load sheave 37 of the pair of sheaves 28 disposed at the first end of the spreader headblock. The rope is then reeved back up over a second sheave 39 of the second pair of sheaves 34 and then further outboard to the end of the gantry where it is secured to one end of a second Jactuator 41.

Wire rope reeving 13B, 15B, similar to that reeved from the first drum reels, is reeved from a third wire rope drum 43 for supporting the other or second end of the lifting spreader headblock, as will be explained more clearly hereinafter.

To prevent or arrest rocking of the load about the coaxially mounted headblock sheaves, two load sheaves 45, 47 are mounted midway from the ends of the spreader headblock and turned 90.degree. with respect to the sheaves on the trolleys.

A third wire rope 17A is reeved from a second wire rope drum 49 outboard along the gantry and around a third set of sheaves 52 disposed at one of the removed edges of the trolley and spreader. The rope is reeved over a first sheave 51 of a third pair of sheaves 52 located on the first trolley disposed closer to the removed edge 53 of the first trolley, down around a third sheave 45 disposed on the edge of the spreader headblock corresponding to the first or lift trolley, back up and over the second sheave 55 of the third pair of sheaves 52. The rope is then reeved further outward along the gantry to the end where it is secured to one end of a third Jactuator 59.

A fourth rope 17B is reeved from the second drum 49, and corresponds to the third rope in its function and reeving, and is reeved through a fourth set of sheaves 60 disposed at the other removed edges of the trolley and spreader. The rope is reeved through a pair of sheaves 60 disposed at the removed edge of the second trolley and the sheave 47 disposed at the corresponding edge of the headblock opposite the edge of the sheave the third rope is reeved through. The end of the rope is secured to the other end of the third Jactuator.

Fifth and sixth ropes 18B, 15B are reeved from the third drum 43 and correspond to the first and second ropes in function and reeving, for supporting the second end of the spreader. The ropes are reeved through a fifth and sixth set of sheaves which include fifth and sixth pairs of sheaves disposed on the second ends of said second and first trolley and a pair of sheaves disposed at the second end of said headblock, and are secured to the second and first Jactuators respectively.

In the preferred embodiment, the 13B, wire rope drums 19,43,49 are utilized for driving the reeving which suspends the spreader. However, two drums could be employed with the three ropes on each side of the center of the spreader headblock being reeved over the same drum, or, all wire ropes could be reeved from a single drum.

As shown more clearly in FIG. 2, the Jactuators are mounted at the end of the boom and are a modified version of the reversing ball screw series 2800 model manufactured by the Duff-Norton Company of Charlotte, N.C. The internal rotating nut of the Jactuator is rotatably confined within its housing 67 and the housing is mounted on or fixed to the end of the boom by a base bracket (not shown), to allow operation along a horizontal axis. A screw shaft 69 is confined within the nut and is transferred laterally in either direction without rotation thereof upon rotation of the power screw drive. Each end of the screw shaft 69 is provided with a clevis or yoke 71, while the ends of the wire rope lines are secured to wedge sockets 73, whereby when the nut is rotated, the respective wire rope line, such as 13, attached thereto will be moved in the direction of the traversing screw shaft.

Each of the Jactuators is preferably actuated by an electric motor 75. Controls for actuation of each motor are remotely operated from a cab mounted on the crane, or from any other suitable position. The drives from the motors to the Jactuators include at least one electrical control limit switch 77 and a spring-set, electric-release, motor-mounted disc brake 79 to prevent overrunning the ends of the Jactuator connections with the ropes.

If desired, the Jactuators may be manually operated by replacing the motor drive means with a handwheel or the like to enable same to be turned by an operator.

OPERATION

Returning now to FIG. 1, the operation of the list, trim, and skew adjustment means of the instant invention will be described. The Z-Z' axis is the longitudinal axis of the ship being loaded in either direction of the arrow, the Jactuator 59 connected between the outward ends of the sway arresting rope 17 is energized in the desired direction to produce a list adjustment motion. This will rotate the load around the Z-Z' axis raising or lowering one side of the load. If listing in the opposite direction is required, the Jactuator is merely reversed. In accordance with this reeving arrangement, the lateral displacement of the spreader and load is negligible enabling an accurate angling of the spreader and load to be obtained.

If it is desired to produce a trim adjustment or alignment about the X-X' axis shown by the arrow, the lifting ropes 13A and B, 15A and B are simultaneously moved by their respective Jactuators 31 and 41 in the same direction. If moved in one direction, the spreader will be trimmed downwardly on the forward end and upwardly on the after end. By reversing the Jactuators, the trim motion of the spreader and the load will be reversed.

Skew adjustment is obtained about the Y-Y' axis in the direction of the arrow by simultaneously moving the same Jactuators 31, 41 on ropes 13A and B, 15A and B in opposite directions. Therefore if one of the Jactuators 31, 41 is moved in one direction while the other Jactuator is moved in the opposed direction, the spreader and load will be skewed clockwise or counter-clockwise as viewed from above. Reversing the Jactuators will reverse the skewing motion. By varying the distance between the movable trolleys, the skewing capacity or degree of movement of the spreader about the Y-Y' axis is adjustable between limits of approximately plus or minus 15.degree. to plus or minus 30.degree..

It is to be understood that the above set forth spreader adjustment means may be furnished in part as well as totally. That is, if arresting lines are not provided, a trim and skew adjustment feature may be provided on the load lifting lines. Likewise other partial adjustment means may be utilized.

It is therefore an important feature of the present invention to provide an apparatus and method for adjusting the spreader load suspension system whereby the list, trim, and skew of the spreader may be mechanically adjusted while the load is suspended from the spreader.

It will be apparent from the foregoing description of the invention in its proferred form that it will fulfill all the objects attributable thereto, and while it is illustrated and described in detail, the invention is not to be limited to such details as have been set forth except as may be necessitated by the appended claims.

Claims

What is claimed is:

1. In a crane reeving system, a list, trim, and skew adjustment means comprising at least one trolley supporting a load lifting spreader by at least three wire ropes driven by at least three wire rope drums, said spreader being defined by two ends and two sides,

a first of said wire ropes being reeved from a first of said wire rope drums outboard along the gantry of the crane and around a first set of sheaves disposed at the first ends of the trolley and spreader and then further outboard and secured to a first Jactuator,

a second of said wire ropes being reeved from said first wire rope drum outboard along the gantry and around a second set of sheaves disposed at the first ends of the trolley and spreader and then further outboard and secured to a second Jactuator,

a third of said wire ropes being reeved from a second of said wire rope drums outboard along the gantry and around a third set of sheaves disposed at one of the removed edges of said trolley and spreader and then further outboard and secured to a third Jactuator,

a fourth rope reeved from said second drum, and corresponding to said third rope, said rope being reeved through a fourth set of sheaves disposed at the other of the removed edges of said trolley and spreader and secured to the third Jactuator,

fifth and sixth ropes reeved from a third drum, and corresponding to said first and second ropes, for supporting the second end of said spreader, said ropes being reeved through a fifth and sixth set of sheaves and secured to the second and first Jactuators respectively, and

means for independent remote operation of said Jactuators to adjust the list, trim, and skew of said spreader.

2. The adjustment means of claim 1 wherein said trolley comprises separable sections reciprocable towards and away from each other and said first, third, and sixth sets of sheaves are disposed on the first trolley and the second, fourth, and fifth sets of sheaves are disposed on the second trolley.

3. The adjustment means of claim 1 wherein said first, second, fifth, and sixth sets of sheaves each include a pair of sheaves disposed on the ends of the trolley and a sheave disposed adjacent to the ends of the spreader, the two sheaves at each end of the spreader forming a pair of sheaves, and the third and fourth sets of sheaves each including a pair of sheaves disposed at the removed opposite edges of said trolley and a sheave disposed at one of the opposite edges of said spreader.

4. In a crane reeving system for handling cargo containers and having a pair of trolleys mounted on the crane gantry for supporting a lifting spreader headblock and being reciprocable with respect to each other, said spreader headblocks being defined by two ends and two sides, a list, trim, and skew adjustment means comprising

a first wire rope being reeved outboard from a first wire rope drum and over a first sheave of a first pair of sheaves disposed at a first end of the first of the two trolleys, down around a first sheave of a pair of sheaves disposed at a corresponding first end of a lifting spreader headblock, back up over the second sheave of the first pair of sheaves, and then further outboard and secured to a first Jactuator,

a second wire rope being reeved outboard from a first wire rope drum and over a first sheave of a second pair of sheaves disposed at the corresponding first end of the second of the two trolleys, down around the second sheave of the pair of sheaves disposed at the first end of the headblock, back up over the second sheave of the second pair of sheaves, and then further outboard and secured to a second Jactuator,

a third wire rope being reeved outboard from a second drum and over a first sheave of a third pair of sheaves disposed at the removed edge of the first trolley, down around a sheave disposed at the corresponding edge of the headblock, back up over the second sheave of the third pair of sheaves, and then further outboard and secured to a third Jactuator,

a fourth rope reeved from said second drum and corresponding to said third rope, said fourth rope being reeved through a fourth pair of sheaves disposed at the removed edge of the second trolley and a sheave disposed at the corresponding edge of the headblock opposite the edge containing the sheave the third rope is reeved through, and said fourth rope being secured to said third Jactuator,

fifth and sixth ropes reeved from a third drum and corresponding to said first and second ropes for supporting the second end of said headblock, said fifth and sixth ropes being reeved through fifth and sixth pairs of sheaves disposed on the second ends of said second and first trolleys and a pair of sheaves disposed at the second end of said headblock and being secured to said second and first Jactuators respectively, and

motor means remotely and independently controllable for actuating said Jactuators to adjust the list, trim, and skew of said headblock.