US3353687A

US3353687A - Cranes

Info

Publication number: US3353687A
Application number: US530274A
Authority: US
Inventors: John S Thomson
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-03-10
Filing date: 1966-02-28
Publication date: 1967-11-21
Anticipated expiration: 1984-11-21
Also published as: GB1104157A

Description

Nov. 2 1, 1967 J. 5 THOMSON L 3,353,687

CRANES Filed Feb. 28, 1966 2 Sheets-Sheet l Inventor c/amv 5 z /oMsa/v Attorneys Nov; 21, 1967 Filed Feb. 28, 1966 J. S. THQMSON CRANES 2 Sheets-Sheet 2 Inventor JOHN 5, 7790/1450 By km ri fwa Attorneys United States -Patent 3,353,687 CRANES John S. Thomson, 104 Forsyth St., Greenock, Scotland Filed Feb. 28, 1966, Ser. No. 530,274 Claims priority, application Great Britain, Mar. 10, 1965, 10,086/ 65 6 Claims. (Cl. 212-58) This invention relates to cranes and especially but not exclusively, to cranes on ships.

According to the present invention, there is provided a crane including a winch having a winding drum, a jib adapted to be mounted for independent lufling and slewing movement on a platform or deck, support means on the free end of the jib and carrying spaced pulley means disposed at the corners of an imaginary isosceles triangle, and additional pulley means mounted on said jib adjacent the point of intersection of the median to-said base and the axis of the jib, said support means being adapted and arranged so that, in use, the base of said triangle is substantially horizontally disposed transversely of and above the axis of the jib, and the median to said base is intersected by said axis so that minimal bending moment is produced in the jib when a load is supported by a load block connected to said spaced pulley means by reaches of rope formed by a single length of rope having its free ends attached to said winch and at least one of said free ends wound around said winding drum, said rope extending in substantially parallel reaches to the pulley means at the apex of said triangle, therearound and downwards to said load block, therearound and divergently upwards around the pulley means at each end of the base of said triangle, then over said additional pulley means and downwards to said lock block.

Further, according to the present invention, there is provided a crane including a winch having a winding drum, a jib, support means on the free end of the jib and carrying spaced pulley means disposed at the corners of an imaginary isosceles triangle, additional pulley means mounted on the jib adjacent the point of intersection of the median to said base and the axis of the jib, said support means being arranged so that the base of said triangle is substantially horizontally disposed transversely of and above the axis of the jib, and a load block supported by a single length of rope having its free ends attached to said winch at least one of said free ends wound around said winding drum, said rope extending in substantially parallel reaches to the pulley means at the apex of said triangle, therearound and downwards to said load block, therearound and divergently upwards around the pulley means at each end of the base of said triangle, then over said additional pulley means and downwards to said load block.

Hereinafter and in the appended claims, the term rope is intended to include any load supporting flexible member adapted for co-operation with pulley means by passing round the pulleys thereof.

An embodiment of the invention will now be described, by way of example, and with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a ships crane according to the present invention. For the sake of clarity, the lufling ropes and other parts have been omitted.

FIG. 2 is a diagrammatic side elevation of the free end of the jib in FIG. 1.

With reference to FIG. 1 of the accompanying drawings, a jib 1 is pivotally mounted on a slewing ring 2, the jib being pivotal in a vertical plane about a pivot 3. The slewing ring 2 is supported on the deck of a ship (not ice shown) and is rotatable about an upright axis so as to vary the angular position of the jib 1 relative to the ship. Suitable power sources (not shown) are provided to control the luffing and slewing movements of the jib 1.

At its free end, the jib 1 has an outrigger 4, which is a Y-shaped frame, the extremities of the arms of which are at the ends of the base, and the extremity of the leg of which is at the apex, of an isosceles triangle, indicated by chain dotted lines 4A. The outrigger 4 carries first pulleys 5 at the extremity of the leg and carries second pulleys 6 at the extremities of the arms. In relation to the jib 1, the first pulleys 5 are disposed substantially in the vertical plane ofthe jib 1, and the two second pulleys 6 are disposed on opposite sides of said vertical plane.

Third pulleys 7 are provided at the attachment point between the jib 1 and the outrigger 4.

A single length of wire rope 8 is provided for load lifting. The free ends of the rope 8 are wound round a winch drum 9 in the same direction; parallel reaches of the rope 8 then pass from the drum 9 over medial pulleys 9A to the first pulleys 5, and thereround; the reaches then pass downwardly from the first pulleys 5 to a load pulley block 10 and thereround; the rope 8 is then looped round the second pulleys 6, forming two upwardly divergent reaches, then round the third pulleys 7, and then in parallel reaches to a snatch block 11 detachably mounted on the load pulley block 10.

The outrigger 4 is disposed transversely of the axis of the jib 1 so that the axis of the jib 1 passes through the isosceles triangle 4A at such a point as to give zero or at least minimal bending moment on the jib 1 due to the tension in the rope reaches between outrigger 4 and load block 10.

As the same number of rope reaches extend to the first pulleys 5 as extend to the second pulleys 6 (i.e., two), in side elevation the first and second pulleys 5 and 6 are disposed at equal distances to either side of the free end of the jib 1. Thus, the bending moments arising from the loads on the first and second pulleys 5 and 6 cancel, and as the loop round the third pulleys 7 is at the free end of the jib 1, it will not have any noticeable bending effect on the jib 1 (FIG. 2.).

In the above described arrangement, the load is sup ported by six rope reaches, two of which extend between the first pulleys 5 and the load block 10, another two of which extend between the second pulleys 6 and the load block 10, and the final two of which extend between the third pulleys 7 and the load block 10. To convert the six part support to a four part support for handling relatively light cargo, the snatch block 11 is detached from the load block 10 and is secured to the base of the jib 1 still retaining the rope 8 looped thereround. This arrangement is shown by chain dotted lines 8A.

Moreover, the jib is provided with a clamp 12 which may be utilized to grip a part of the rope 8A to prevent it from moving along its own axis. The clamp 12 may be conveniently attached to the jib so that the rope may be gripped when rigged for four part load support. This additional feature is very advantageous in that, during slewing the rope 8A is unable to move and, therefore, firm anti-pendulum slewing is ensured.

It will be manifest that the example above-described is also advantageous in that there is negligible bending moment in the jib 1. It may of course be the case that the bending moment is not exactly zero due to constructural inaccuracies, but it will, of course, be a negligible value, and it is intended that the invention covers such a case.

When the jib 1 is converted to a four reach support there is a considerable reduction in the amount of rope 8 which the winch drum 9 must handle, as part of the rope 8 remains close to the jib 1. Even in the case where there are six reaches supporting the load, there is a noticeable length of rope which the winch drum 9 does not have to accommodate.

Any reduction of the amount of rope to be wound onto a. winch drum is desirable, as when the number of rope layers on the drum becomes too great, the torque factor of the winch is adversely affected.

Another important feature of the above-described example is the speed at which the crane may be converted for light cargo as compared with known cranes. With the described example, the conversion may be completed in ten minutes; in known cranes it may be several hours as the crane rigging :must be dissembled and re-reeved.

It will be understood that in modifications where the number of rope reaches extending between the first pulleys 5 and the load block 10- is greater than or less than the number of rope reaches extending between the sec ond pulleys 6 and the load block 10-, the point of intersection of the jibs axis with the isosceles triangle 4A would require to be correspondingly altered so as to give thenegligible, bending condition.

In a modification only one of the free ends of the single length of rope is wound round the winding drum 9, the other of said free ends being anchored, for example to the winch body. This modification provides a higher velocity ratio for handling heavy loads.

Additionally, the slewingarrangement may be modified, for example, the jib pivot 3 may be mounted separately from the winch, and further, the outrigger may be modified in design so that part thereof is formed by an extension of; the jib.

I claim:

1. A crane including a winch having a winding drum, a jib adapted to be mounted for independent luffing and slewing movement on a platform or deck, support means on the free end of the jib and carrying spaced pulley means disposed at the corners of an imaginary isosceles triangle, and additional pulley means mounted on said jib adjacent the point of intersection of the median to said base and the axis of the jib, said support means being adapted and arranged, so that, in use, the base of said triangle is substantially horizontally disposed transversely of and above the axis of the jib, and the median to said base is intersected by said axis so that minimal bending moment is produced in the jib When a load block connected to said spaced pulley means by reaches of rope formed by a single length of rope having its free ends attached to said winch and at least one of said free ends wound around said winding drum, said rope extending in substantially parallel reaches to the pulley means at the apex of said triangle, therearound and downwards to said load block, therearound and divergently upwards around the pulley means at each end of the base of said triangle, then over said additional pulley means and downwards to said load block.

2. A crane according to claim 1, in which there is provided a pulley block connected to said load block so that the reaches extending downwards from the additional pulley means may be connected to said load block by passing the rope around said pulley block.

3. A crane according to claim 2;, in which said pulley block is detachably connected, to the load block.

4. A crane according to claim 3, in which there is provided, adjacent the end remote from the free end of the jib, a hook or eye to which said pulley block with the rope therearound may be attached alternatively to being attached to saidload block.

5. A crane according to claim 4, in which there is provided clamp means for preventing movement relative to the jib of the reaches extending downwards from the additional pulley means when said pulley block with said last-mentioned reaches therearound is attached to said hook or eye.

6. A crane including a winch having a winding drum, a jib, support means on the free end of the jib and carrying spaced pulley means disposed at the corners of an imaginary isosceles triangle, additional pulley means mounted on the jib adjacent the point of intersection of the median to. said base and the axis of the jib, said support means being arranged so that the base of said triangle is substantially horizontally disposed transversely of and above the axis of the jib, and a loadblock supported by a single length of rope having its free ends attached to, said winch and at leastwone of said freev ends wound around said winding drum, sa-id rope extending in substantially Parallel reaches to the pulley means at the apex of said triangle, therearound and downwards to said load block, therearound and; divergently upwards around the pulley means at each end of the base of said triangle, then over said additional pulley means and down wards to said load block.

ANDRES H. NIELSEN, Primary Examiner.

Claims

1. A CRANE INCLUDING A WINCH HAVING A WINDING DRUM, A JIB ADAPTED TO BE MOUNTED FOR INDEPENDENT LUFFING AND SLEWING MOVEMENT ON A PLATFORM OR DECK, SUPPORTING MEANS ON THE FREE END OF THE JIB AND CARRYING SPACED PULLEY MEANS DISPOSED AT THE CORNERS OF AN IMAGINARY ISOSCELES TRIANGLE, AND ADDITIONAL PULLEY MEANS MOUNTED ON SAID JIB ADJACENT THE POINT OF INTERSECTION OF THE MEDIAN TO SAID BASE AND THE AXIS OF THE JIB, SAID SUPPORT MEANS BEING ADAPTED AND ARRANGED, SO THAT, IN USE, THE BASE OF SAID TRIANGLE IS SUBSTANTIALLY HORIZONTALLY DISPOSED TRANSVERSELY OF AND ABOVE THE AXIS OF THE JIB, AND THE MEDIAN TO SAID BASE IS INTERSECTED BY SAID AXIS SO THAT MINIMAL BENDING MOMENT IS PRODUCED IN THE JIB WHEN A LOAD BLOCK CONNECTED TO SAID SPACED PULLEY MEANS BY REACHES OF ROPE FORMED BY A SINGLE LENGTH OF ROPE HAVING ITS FREE ENDS ATTACHED TO SAID WINCH AND AT LEAST ONE OF SAID FREE ENDS WOUND AROUND SAID WINDING DRUM, SAID ROPE EXTENDING IN SUBSTANTIALLY PARALLEL REACHES TO THE PULLEY MEANS AT THE APEX OF SAID TRIANGLE, THEREAROUND AND DOWN-