US3144136A

US3144136A - Rope drive for swinging boom of a jib crane

Info

Publication number: US3144136A
Application number: US278025A
Authority: US
Inventors: Richard J Mcafee; Steckle Charles
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1963-05-06
Filing date: 1963-05-06
Publication date: 1964-08-11
Anticipated expiration: 1981-08-11

Description

Aug. 11, 1964 3,144,136

R. J. M AFEE ETAL ROPE DRIVE FOR SWINGING BOOM OF A JIB CRANE 2 Sheets-Sheet 1 Filed May 6, 1963 INVENTORS. RICHARD J. M AFEE and CHARLES .STECKLE Attorney Aug. 11, 1964 v R. J. MCAFEE ETAL ROPE DRIVE FOR SWINGING BOOM OF A JIB CRANE 2 Sheets-Sheet 2 Filed May 6, 1963 INVENTORS. RICHARD J. M AFEE and CHARLES STECKLE 9%,9 a

Attorney United States Patent Candless Township, Allegheny County, Pa., assignors to United States Steel Corporation Filed May 6, 1963, Ser. No. 278,025 2 Claims. (Cl. 212-66) The present invention relates generally to cranes and, more particularly, to an improved rope drive for driving the boom of a jib crane.

Prior to our invention, swinging of a jib crane boom was frequently accomplished by means of two ropes or cables, each of which was fastened by one end to opposite sides of the free end of the boom. Each of the ropes passed over a sheave and was attached at its other end to a rotatable drum. Then, as the drum was rotated, the rope leading from the side of the boom in the direction in which it was desired to swing the boom would be Wound on the drum and the rope leading from the other side of the boom would be wound off the drum.

A serious disadvantage inherent in the drive arrangement just described was the fact that although the rope pulling or towing the boom was shortened" by being found on the drum as the boom moved from its center position and the other or trailing rope was lengthened by being wound off the drum, the respective ropes were not shortened and lengthened equally due to the arcuate path traveled by the free end of the boom to which the ropes were fastened. The trailing rope lengthened faster than the towing rope was shortened so that a certain amount of slack was created in the trailing rope. This caused the boom to swing uncontrollably in the direction toward the towing rope and thus created a potential safety hazard for workmen in the vicinity of the jib crane boom.

It is, accordingly, one of the objects of our invention to provide an improved rope drive for swinging the boom of a jib crane whereby the movement of the boom is under control at all times as it is moved in either direction from its center position.

It is a more specialized object of our invention to provide a rope drive of the character set forth in the above object which includes a traveling sheave arrangement for automatically taking up any slack created in the rope drive during swinging movement of the boom in either direction from its center position.

These and other objects will become more apparent after referring to the following specification and attached drawings, in which:

FIGURE 1 is an elevational view of a jib crane having the rope drive of the invention connected therewith;

FIGURE 2 is a diagrammatic illustration of the rope drive of the invention; and

FIGURE 3 is an isometric view of a jib crane having the rope drive of the invention connected therewith.

Referring more particularly to the drawings, reference numeral 2 designates an upright standard which may be in the form of an H-beam having a jib crane 4 mounted thereon. The jib crane 4 is provided with a boom 6 which extends from a post 8 journaled in a pair of vertically spaced bearings 10 of the crane. A diagonal truss member 12 extends between the boom and the post. The boom 6 swings in an arcuate path radially of the crane in the usual manner. The boom is swung or driven to one side or the other by the rope drive of our invention which will now be described.

The rope drive of the invention includes a rotatable drum 14 journaled for rotation in a bracket 16 which is mounted on the standard 2 on the side thereof opposite "ice to and below the jib crane 4. A length of rope or cable 18 is laid about the drum 14. An elevated way in the form of a trackway 2t) comprised of a pair of spaced parallel rails 22 each mounted on supporting I-beams is located above the drum 14. The trackway 20 extends in a horizontal plane transversely of an extension of the longitudinal axis of the boom 6 when the boom is in its center position as best shown by solid lines in FIGURE 2.

A carriage or trolley 24 comprising a pair of wheels 26 rotatably mounted on opposite ends of an axle shaft 23 is mounted for movement along the trackway 26 with the wheels 26 traveling along the rails 22. A tiltable lever 30 is pivotally mounted intermediate its ends on the axle shaft 28 between the wheels 26. Sheaves 32 and 34 are mounted on opposite ends of the lever 30 for rotation in a vertical plane. Sheaves 36 and 33 are mounted in fixed positions adjacent opposite ends of the trackway 20 for rotation in a horizontal plane.

One end 40 of rope 18 extends from the drum 14, passes around vertical sheave 32 and horizontal sheave 36 to a point of attachment to the left side of boom 6 adjacent its free end, as best seen in FIGURES 2 and 3. The opposite end 42 of rope 18 leads from the drum 14, passes around vertical sheave 34 and horizontal sheave 38 to a point of attachment to the right side of the boom 6 adjacent its free end.

In operation, when it is desired to swing boom 6 to the right as seen in FIGURE 2, the drum 14 is rotated (manually or by suitable power means, not shown) in clockwise direction. Clockwise rotation of drum 14 causes the end 42 of rope 18 to be wound on the drum so that the boom 6 is pulled or towed to the right, as shown by broken lines in FIGURE 2. While rope end 42 is being wound on the drum, it is tensioned and exerts a component of force against vertical sheave 34. At the same time, dope end 40 is wound off the drum and slackened. The component force being exerted on vertical sheave 34 by rope end 42 causes the right end of lever 30 to tilt downwardly and the carriage 24 to move to the right along trackway 20, as shown by broken lines in FIGURE 2. When the right end of lever 36 tilts downwardly, vertical sheave 32 on the left end of the lever tilts upwardly and exerts tension on the slack rope end 40. This tension is increased by the carriage moving to the right along the trackway until all of the slack is eliminated from rope 40.

When the drum 14 is rotated in counterclockwise direction, the boom 6 will be swung to the left. At the same time, the carriage will move to the left along the trackway, and the left end of lever 36 will be tilted downwardly under tension of towing rope end 4%). When lever 30 tilts, vertical sheave 32 will be shifted upwardly. As the carriage moves to the left with sheave 32 lifted upwardly, increasing tension will be exerted on the trailing rope end 42 to eliminate slack therefrom.

In installations where the boom of the jib is required to be swung a relatively short distance, the

sheaves

32 and 34 may be mounted on the carriage in non-tiltable relation thereto. Sufficient tension will be exerted on the trailing rope to eliminate slack therefrom solely by movement of the carriage along the trackway.

Although we have shown and described carriage 24 as being mounted on top of a horizontally disposed trackway 20, it will be understood that the carriage could be suspended from an overhead way, if desired. Further, if desired, the drum 14 could be mounted above the trackway 20 or it could be positioned to rotate about a vertical axis in a horizontal plane common with the horizontal plane containing the trackway. In the latter case, all of the

sheaves

32, 34, 36 and 38 would preferably be positioned to rotate about vertical axes.

While one embodiment of our invention has been shown Patented Aug. 11, 1964 and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

We claim: t

1. The combination with a jib crane having a boom pivoted at one end for swinging movement in a horizontal arcuate path radially of said crane of a rope drive for swinging said boom which comprises a rotatable drum journaled in a vertical plane adjacent the vertical plane containing the pivoted end of said boom, a length of rope laid about said drum, an elevated way adjacent the pivoted end of said boom, said way extending in a horizontal plane transversely of an extension of the longitudinal axis of said boom when said boom is positioned in the center of its path, a carriage mounted for movement along said way, a first sheave journaled on one end of said carriage and a second sheave journaled on the other end thereof, a third sheave journaled at a fixed point adjacent the end of said way toward said first sheave, and a fourth sheave journaled at a fixed point adjacent the opposite end of said way, one end of said length of rope extending from said drum and first passing around said first sheave and then around said third sheave to a point of connection with the free end of said boom, and the other end of said length of rope extending from said drum and first passing around said second sheave and then around said fourth sheave to a point of connection with the free end of said boom.

2. The combination with a jib crane having a boom pivoted at one end for swinging movement in a horizontal arcuate path radially of said crane of a rope drive for swinging said boom which comprises a rotatable drum journaled in a vertical plane adjacent the vertical plane containing the pivoted end of said boom, a length of rope laid about said drum, an elevated way adjacent the pivoted end of said boom, said way extending in a horizontal plane transversely of an extension of the longitudinal axis of said boom when said boom is positioned in the center of itspath, a carriage mounted for movement along said Way, a 'tiltable lever carried by said carriage, said lever being tiltable about a horizontal axis extending transversely of said way, a first sheave journaled on one end of said lever and a second sheave journaled on the other end thereof, a third sheave journaled at a fixed point adjacent the end of said way toward said first sheave, and a fourth sheave journaled at a fixed point adjacent the opposite end of said way, one end of said length of rope extending from said drum-and first passing around said first sheave and then around said third sheave to a point of connection with the free end of said boom, and the other end of said length of rope extending from said drum and first passing around said second sheave and then around said fourth sheave to a point of connection with the free end of said boom.

References Cited in the file of this patent UNITED STATES PATENTS 3,057,484 Trevisan Oct. 9, 1962 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No., 3,, 14M 136 August 11, 1964 Richard J, McAfee et ale It is hereby certified that error appears in the above numbered etent requiring correction and that the said Letters Patent should read as corrected below.

Column 1 line 26, for "found" read wound column 2 line 31 for "be "wound on" read be "wound on" line 36 for "dope" read rope Signed and sealed this 24th day of November 1964c (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer a Commissioner of Patents

Claims

2. THE COMBINATION WITH A JIB CRANE HAVING A BOOM PIVOTED AT ONE END FOR SWINGING MOVEMENT IN A HORIZONTAL ARCUATE PATH RADIALLY OF SAID CRANE OF A ROPE DRIVE FOR SWINGING SAID BOOM WHICH COMPRISES A ROTATABLE DRUM JOURNALED IN A VERTICAL PLANE ADJACENT THE VERTICAL PLANE CONTAINING THE PIVOTED END OF SAID BOOM, A LENGTH OF ROPE LAID ABOUT SAID DRUM, AN ELEVATED WAY ADJACENT THE PIVOTED END OF SAID BOOM, SAID WAY EXTENDING IN A HORIZONTAL PLANE TRANSVERSELY OF AN EXTENSION OF THE LONGITUDINAL AXIS OF SAID BOOM WHEN SAID BOOM IS POSITIONED IN THE CENTER OF ITS PATH, A CARRIAGE MOUNTED FOR MOVEMENT ALONG SAID WAY, A TILTABLE LEVER CARRIED BY SAID CARRIAGE, SAID LEVER BEING TILTABLE ABOUT A HORIZONTAL AXIS EXTENDING TRANSVERSELY OF SAID WAY, A FIRST SHEAVE JOURNALED ON ONE END OF SAID LEVER AND A SECOND SHEAVE JOURNALED ON THE OTHER END THEREOF, A THIRD SHEAVE JOURNALED AT A FIXED POINT ADJACENT THE END OF SAID WAY TOWARD SAID FIRST SHEAVE, AND A FOURTH SHEAVE JOURNALED AT A FIXED POINT ADJACENT THE OPPOSITE END OF SAID WAY, ONE END OF SAID LENGTH OF ROPE EXTENDING FROM SAID DRUM AND FIRST PASSING AROUND SAID FIRST SHEAVE AND THEN AROUND SAID THIRD SHEAVE TO A POINT OF CONNECTION WITH THE FREE END OF SAID BOOM, AND THE OTHER END OF SAID LENGTH OF ROPE EXTENDING FROM SAID DRUM AND FIRST PASSING AROUND SAID SECOND SHEAVE AND THEN AROUND SAID FOURTH SHEAVE TO A POINT OF CONNECTION WITH THE FREE END OF SAID BOOM.