United States Patent 3868023

Disclosed is a crane and boom attachment for lifting wide loads to substantial heights as is required in constructing large buildings. Mounted on the end of the crane boom is a horizontally extending framework secured at widely spaced points to the boom end and stabilized by a pair of pendant cables connected to the attachment at least half way up from its lower edge. The pendant cables are received over the ends of a transverse shaft to provide good torsional stability for the crane and boom attachment.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
212/262, 212/264, 212/347
International Classes:
B66C23/66; (IPC1-7): B66C23/66
Field of Search:
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US Patent References:
3198345Crane1965-08-03Brekelbaum et al.
3134488Crane1964-05-26Brekelbaum et al.
3037641Tower crane attachment1962-06-05Potter et al.
1944972Transformable lifting appliance1934-01-30Faure et al.

Primary Examiner:
Schacher, Richard A.
Assistant Examiner:
Rowland, James L.
Attorney, Agent or Firm:
LeBlanc & Shur
Parent Case Data:

This is a continuation of application Ser. No. 264,523, filed June 20, 1972, which in turn is a continuation of application Ser. No. 29,517, filed Apr. 17, 1970.
What is claimed and desired to be secured by United States Letters Patent is

1. A hoisting crane for handling wide loads comprising a movable undercarriage, a control cab mounted on said undercarriage, a crane boom pivoted at its lower end to said undercarriage and extending upwardly and outwardly from said cab, the upper end of said boom having a substantially rectangular cross section, a bridle, gantry cables coupled to said cab and said bridle for raising and lowering said boom, an attachment for said boom comprising a framework including a boom connecting section, a laterally extending section, and a crown section surmounting and substantially laterally coextensive with said boom connecting and laterally extending sections, said boom connecting section having a substantially rectangular end, means for securing the rectangular ends of said boom and said connecting section one to the other such that said connecting section forms an axial extension of said boom, a first hoist cable sheave mounted on the end of said laterally extending section remote from said boom connecting section, a second hoist cable sheave on said crown on the side of the boom axis remote from said first sheave, said second sheave constituting the highest point of said crane, the distance between the boom end and said second sheave extending along a line parallel to the boom axis being less than the generally horizontal distance between said first sheave and the boom axis at the boom end, a transverse support mounted at the upper end of said connection section, a pair of stabilizing cables, and means securing said stabilizing cables to the opposite ends of said transverse support and to said bridle.

2. A crane according to claim 1 wherein said stabilizing cables, transverse support rod and bridle lie on like sides of the boom axis.

3. A crane according to claim 2 wherein the adjacent sides of said crane boom and said attachment intersect at an angle of approximately 114°.

4. A crane according to claim 2 wherein said transverse support is located about two-thirds of the way up from the bottom of said attachment.

5. A crane according to claim 4 wherein said crown and laterally extending sections both taper to a narrower cross section in a direction away from said connecting section, said second hoist cable sheave mounted at the top of said crown section.

6. A crane according to claim 5 wherein said stabilizing cables extend in substantially parallel relation one to the other from said bridle along the opposire sides of said boom and said attachment wereby said stabilizing cables are spaced transversely one from the other substantially the full width of the boom.

This invention relates to a hoisting crane and, more particularly, to a crane boom attachment which makes it possible to increase the torsional stability of the crane and also to increase the lifting height of the crane for wide loads.

A variety of hoisting cranes are available for lifting large, heavy loads. These include both the statutory and so-called portable cranes. For the purposes of building construction, the portable crane is desirable since it is more readily moved to a new site once the building has been completed. In spite of this fact, stationary, and more particularly towertype cranes, have come into widespread use. One of the reasons has been the fact that, in order to lift relatively large loads such as prefabricated building elements several stories in height, the boom of a portable crane is necessarily quite long. The excessive boom length makes it necessary to at least partially dismantle the boom before it can be easily transported through city streets.

As a result, it has become common practice, when using portable cranes in the construction of relatively large buildings, to attach to the boom tip a short removable boom section, often referred to as a jib. The jib may be adjusted to different angles with respect to the main boom and is readily removed for greater ease in transporting the crane to a new site when the job is done. While the addition of a removable job helps to increase the overall length of the crane boom and increase the height to which loads may be lifted, it tends to reduce the lateral or torsional stability of the crane boom assembly and reduces the weight of the loads which might otherwise be handled by the crane.

The present invention avoids these and other difficulties by providing an improved crane boom attachment adapted to be secured to the end of a crane boom which not only significantly increases the height to which large loads may be lifted without significantly increasing the overall boom length, but also substantially improves lateral stability so that the crane is able to handle heavier loads in a greater variety of lifting positions. While the crane and crane boom attachment of the present invention are usable for all types of hoisting applications, including those requiring both portable and stationary cranes, the present invention is particularly adapted for incorporation in a portable crane usable for hoisting large prefabricated building sections in the construction of multi-story buildings. It is particularly useful for raising and putting in place prefabricated concrete tee and channel sections of the type shown and described in my copending application, Ser. No. 397,711, filed Sept. 17, 1973.

One of the difficulties in lifting relatively large, heavy loads, such as concrete sections for buildings, lies in the fact that the sections often have a wide span and a substantial distance must be maintained between the crane hook and the boom to provide a clearance for the load being lifted. This clearance must be maintained up to the maximum lifting height when working on higher floors. Changing the angle of the boom so as to increase this clearance is of limited value since it reduces the weight of the load that can be lifted by the crane. The conventional jib boom does not solve this problem since the jib boom is normally connected to the tapered end of the main boom with lateral stability provided by a pair of so-called pendant cables connected to the boom tip on opposite sides of the boom tip sheave. The resulting lateral or torsion loads exerted on the boom tend to make it unstable and seriously limit the loads that can be readily handled by the crane.

In the present invention, a framework forming a boom attachment is secured to the untapered end of the main boom and extends substantially horizontally outwardly from the boom end to increase the clearance between the crane hook or other load lifting apparatus and the boom body without at the same time significantly increasing the overall length of the boom. In addition, the crane boom attachment is provided with a transverse shaft adjacent its extreme upper end of substantial width to which are attached the crane pendant cables. Because of the increased height to the point of attachment of the pendant cables and the increased space between the ends of these cables, the crane of the present invention evidences increased torsional stability and is capable of handling greater loads with more versatility.

It is, therefore, one object of the present invention to provide an improved attachment for the end of a crane boom.

Another object of the present invention is to provide an improved crane having a substantially horizontally extending attachment secured to the upper end of the crane boom.

Another object of the present invention is to provide hoisting crane having improved torsional stability.

Another object of the present invention is to provide an attachment for crane booms which makes it possible to lift large loads to greater heights without significantly increasing the overall length of the crane boom.

Another object of the present invention is to provide a crane and crane boom attachment particularly suited for use on a portable crane used in building construction to lift prefabricated structures, such as concrete channels and tee sections, up to even the highest floor of the building being constructed.

These and further objects and advantages of the invention will be more apparent upon reference to the following specification, claims and appended drawings wherein:

FIG. 1 is a perspective view of a portable hoisting crane constructed in accordance with the present invention;

FIG. 2 is an enlarged perspective view of the upper end of the boom of the crane of FIG. 1, showing the novel crane boom attachement of the present invention;

FIG. 3 is a side view of the upper end of the crane boom of FIG. 1;

FIG. 4 is a top plan view of the crane boom attachment;

FIG. 5 is an end view of the crane boom of FIG. 1 showing the manner of securing the attachment to the end of the main boom;

FIG. 6 shows the end of the pendant cables which provide torsional stability for the crane boom;

FIG. 7 is an end view of the main boom; and

FIG. 8 is a diagramatic showing of the crane boom and attachment in relation to a hoisting load in the form of a concrete tee section, used in the contruction of buildings.

Referring to the drawings, the crane of the present invention is generally indicated at 10 in FIG. 1. The crane shown is of the track crawler type and comprises a cab 12 and rotatable undercarriage 14 mounted on a pair of caterpillar type tracks 16 and 18. Pivoted to the undercarriage 14 of the crane is one end of a main boom 20, formed from several boom sections each consisting of a latticework of metal angle irons. Secured to its upper end or to the outermost section of the boom is a crane boom attachment generally indicated at 22. Mounted on attachment 22 are a pair of blocks 24 and 26 over which pass the hoist line 28 carrying a crane hook 30, or other suitable hoisting attachment. Extending upwardly from the cab 12 are the usual gantry cables 32, cooperating with the bridles 34 and 36 for raising and lowering the end of the boom. While only three gantry cables are illustrated, in the preferred embodiment the crane is provided with a six-section gantry cable configuration with one end connected to a suitable drum and drive mounted in cab 12 and power-operated to raise and lower the boom. Extending upwardly from bridle 34 are a pair of pendant cables 38 and 40 which are secured at their upper ends to the opposite ends 42 and 44 of a shaft of 46 mounted near the top of attachment 22.

FIG. 3 is a side elevation of the end of the boom 20, showing the attachment 22 to an enlarged scale. FIG. 4 is a top plan view of the attachment. Attachment 22 is comprised of a plurality of criss-crossing angle irons 48 which form an open framework generally consisting of three integral sections, namely connecting section 50, laterally extending section 52, and upwardly extending section or crown 54. Connecting section 50 is connected to the extreme end 56 of boom 20, and includes one side 58 which forms an extension of the boom. Section 50 is of rectangular cross-section and is attached to the four corners of the end of the boom. Lateral section 52, on the other hand, tapers from edge 60 outwardly and carries at its outer end sheave block 26. Similarly, crown 54 of attachment 22 tapers in an upward direction and mounted at its upper end is the sheave block 24.

An important feature of the present invention is that the boom 20 does not carry the usual tapered boom tip or tapering end section, but instead is made up so that the last section, such as section 62 of the boom, is of uniform rectangular cross-section along its entire length. The end 56 of the boom, as illustrated in FIG. 7, is provided with integral ears 64, 66, 68 and 70 apertured to receive bolts which cooperate with similar ears on attachment connecting section 50 to secure attachment 22 to the end of the boom. Two of the attaching ears on the section 50, illustrated at 72 and 74 in FIG. 5, are clamped to the end 56 of the boom by bolts 76 and 78. It is understood that the opposite corners of the two sections are similarly bolted together. In this way, attachment 22 is secured to the boom at four widely spaced points so as to provide excellent stability for attachment 22 under all types of loading conditions.

Secured to the top of attachment connecting section 50 is a transverse shaft 76, which is welded or otherwise suitably secured to the open framework. The ends of the pendant cables are provided with grommets 78 and 80, one of which is shown to an enlarged scale in FIG. 6. These grommets are received over the ends of transverse shaft 76. The grommets and therefore the end of the pendant cables, are secured to the shaft by washers 82 and cotter pins 84 passing through suitable apertures in the extreme ends of the shaft 76. In this way, the pendant cables 38 and 40 are anchored to attachment 22 at two widely spaced points adjacent the ends of shaft 76 which points may typically be separated by a distance of from 21/2 to 3 feet, so as to provide improved torsional stability for the boom and boom attachment.

FIG. 8 is a diagramatic showing of the end of the boom and the boom attachment in relation to a typical load, such as prefabricated tee section forming one of the components of a large commercial building, as more fully disclosed in my copending application, Ser. No. 397,711, filed Sept. 17, 1973, the disclosure of which is incorporated by reference. In FIG. 8, certain dimensions for the attachment are given, establishing necessary relationships for clearance and load-handling between the boom, the attachment, and the T-section load, illustrated at 80 in that figure. T-section 80 is formed of concrete and includes a vertical stem 82 joined to a pair of flanges 83 and 84, which flanges may typically span an overall width of 6 feet, 2 inches. Hoist line 28 is connected to the top of the stem and the T-section 80 is lifted in the position illustrated in FIG. 8.

It is apparent that there must be a sufficient clearance between hoist line 28 and the body of boom 20 to provide for the substantial extend of flange 84. For a T-span or flange of this size, the overall length Q of the lower edge of the attachment is typically about 41/2 feet to provide a minimum clearance Z between the edge of the T-section 80 and the extreme end of the boom 20 of at least 1 foot. Typically, the minimum clearance between the top of the T-load and the bottom of the attachment as indicated at 90, is two feet, so that the distance d between the top of the load and the nearest portion of the boom is well over a foot and more in the neighborhood of 2 feet.

For a base Q of approximately 41/2 feet, the overall height of attachment 22, indicated at X in FIG. 8, is typically about 8 feet. The length R of side 58 of the attachment is dependent upon the thickness of the boom, indicated at f, and depends upon the particular load requirements. The pendant cables connected to shaft 76 are connected at a distance g from the end 56 of the boom, preferably at a point approximately two-thirds the length of side 58, that is, g = 2/3 R. This may vary somewhat in accordance with design loads but, in general, the pendant cables should be connected at least half-way up side 58 of the attachment. Typically, the boom projects upwardly at an angle of approximately 66°, and it is preferred that the base of the attachment be substantially horizontal under these circumstances so that the angle between the lower edge of attachment 22 and the lower edge of boom 20 is approximately 114°.

It is apparent from the above that the present invention provides an improved boom and boom attachment particularly adapted for lifting large, relatively unwieldy loads to substantial heights as is necessary in constructing large commercial buildings. Important features of the invention include a relatively short, laterally extending attachment which does not significantly increase the overall boom length, and yet one which makes it possible to lift relatively wide loads, such as concrete channel, L and T building sections, and, at the same time, evidences improved torsional stability through the connection of pendant cables to widely spaced points on the boom attachment itself. Normally, weight distribution and other factors limit the maximum boom angle to about 80°. With the attachment of the present invention, the weight distribution is such that the boom can go up to an angle of about 85° to increase the lifting height of the crane. This makes it possible to significantly increase the load capacity of the crane without danger of tipping and allows the use of a shorter boom due to the steeper angle permitted by the construction.

It is, of course, understood that the above examples are given by way of example only and may vary widely depending upon the size and weight of the loads which it is desired to lift with the boom. However, in all cases, the boom attachment is secured to the four corners of boom end 56 having a substantial width so as to provide improved stability at the point of attachment, the attachment extends laterally or substantially horizontally when the boom is at or close to its normal operating position, and a pair of pendant cables are attached at least midway up the attachment at two widely spaced points to provide improved tortional stability, such as by being attached to the ends of the transverse shaft 76, as illustrated. These features all combine to make it possible to decrease the overall length of the boom and, at the same time, accommodate heavy and wide loads .