Self-erecting Crane To Be Towed By A Truck

Abstract

In a tower crane consisting of three articulated members, viz. one lower member hinged to the slewing crane frame, a middle member articulated to the said lower member and articulated to the opposite end to the crane boom, the provision of an inextensible cable fixed at one end to the said slewing frame of crane and to the other end to the said middle member adjacently to the articulation between the said lower member and middle member, said inextensible cable being wound around an arcuated sector fixed to the middle member, whereby swinging of the hinged lower member by a capstan by means of a tackle device causes the self-erection of the tower.

Description

FIELD OF THE INVENTION

The invention relates to self-erecting tower cranes adapted to be towed by a road vehicle.

The crane is of the kind comprising a lower arm hinged to a crane frame rotatable about a vertical axis, a middle arm hinged at one end to the lower arm and at the other end to a third arm operating as a crane boom.

The object of the invention is to provide a crane of simplified structure, wherein the number of parts are substantially reduced and some parts perform a number of operations.

Furthermore, it is the object of the invention to provide a crane that can be erected or unfolded in a matter of a few seconds.

SUMMARY OF THE INVENTION

According to the invention the crane is characterized by the provision of an inextensible cable fixed at one end to the said rotatable frame of the crane and to the other end to the said middle arm adjacent to the hinge between the said lower arm and middle arm, said inextensible cable being wound around an arcuate sector fixed to the middle arm, whereby swinging of the hinged lower arm by a capstan by means of a tackle device causes the opening out of the said middle arm from the said lower hinged arm.

According to a further feature one end of the cable of the tackle device is fixed to the crane boom, and after the self-erection of the crane and fastening of the lower arm and middle arm, and after opening out of the crane boom by means of a third cable, the same cable of the tackle device is utilized for vertically handling of a load.

The crane capstan is provided with a flange with a notch for the rapid coupling of the end of a branch of the cable for hoisting the crane boom, so as a different inclination of the boom is rendered possible by winding the said branch upon the capstan drum and by fixing another portion of the cable for hoisting the crane boom to the crane frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a detailed description of one embodiment of the invention, by way of example only, with reference to the accompanying drawings, wherein:

FIG. 1 is a diagrammatic side elevation of the crane in the folded position,

FIG. 2 shows at a larger scale the portion A of FIG. 1 of the crane boom,

FIGS. 3 and 4 show as FIG. 1 diagrammatically in side elevation the crane in two intermediate stages during the self-erection,

FIG. 5 shows diagrammatically in side elevation the crane in its final self-erected stage,

FIG. 6 shows at a larger scale the portion B of FIG. 5,

FIG. 7 shows at a larger scale the detail of the arcuated sector as visible in the FIG. 1,

FIG. 8 shows at a larger scale the portion D of FIG. 5,

FIG. 9 is a longitudinal schematic section of the drive capstan,

FIG. 10 is an elevation of the left side of FIG. 9 of the capstan showing the detail of the stop notch,

FIG. 11 shows at a larger scale the detail of the free hook end of the cable for modifying the inclination of the crane boom.

The crane essentially consists of a capstan 1 driven by an electric motor, not shown, and mounted upon the crane frame 2, the latter being supported and rotatable upon a wheeled carriage 3 about a vertical axis. The foldable crane structure consists of three main parts, namely the boom F, a middle arm G and a lower arm H horizontally pivoted at 4 in the rotatable frame 2. The boom F and the middle part G are hinged at 5 adjacent to a pulley 6 and to the tip 7. The arm H and the middle arm G together form the tower of the crane and are hinged at 8 as shown. The truck 3, adapted to be towed by a road vehicle 9 is not particularly described since it is well known in the art.

There is provided a tackle comprising a first set of sheaves 10 mounted at the bottom of the slewing frame 2, a second set of sheaves 11 mounted adjacent to the free end of the pivoting arm H and a first cable L represented by a chain-dotted line (-.-.-.-) wound around the pulley 13, FIG.3, and around the pulley 14, the latter being coaxial with hinge 8 and then wound around a pulley 6 and lastly around the sheaves 16 - 17, then fixed at 15 to the boom F adjacent to the hinge 5. The cable L is of course fixed at its opposite end to the capstan drum.

A second cable M, represented by a chaindotted line (-.-.-.-) has one end fixed at 18 to the frame 2, while the other end is fixed at 19 to the end of arm G after having passed around the pulley 20, along the arm H and engaging an arcuate sector 21 as shown in FIGS. 7 and 8. This sector 21 traverses a slot 22 formed in the U profiled pivoting arm H when the crane is in the extended position, FIGS. 8 and 5. A spring 23 is frictionally housed into a sleeve fixed to the middle arm G and cooperates with a bracket 24 fixed to the pivoting arm H, whereby, as soon as the arm G and H assume an aligned position, the spring is compressed. This results in a reaction in a clockwise direction, FIG. 8, which induces the folding of the crane during the folding operation. A bolt 25 is preferably provided for imparting the maximum reaction of the spring. According to a further feature there is provided a third cable N represented with full lines and fixed at one side at 18 to the frame 2 and at the other side to the tip 7 and to the end of boom F. From this cable N a branch N' is wound around the capstan 1 after having its end 26 hooked within the L-profiled notch 27 of capstan drum flange 29. The branch N' is represented thus -...-...-...-.

The operation of the crane according to this invention is as follows:

When the capstan 1 is driven, the pivoting arm H is swung anticlockwise as seen in FIG. 1 and at an intermediate stage the cable M passes from a loose condition to a stretched condition. Since the cable M is inextensible, and its length is constant and the swinging of the hinged arm H strives to extend the cable M, there occurs an opening out movement of parts G and H until an alignment thereof is obtained. Also, the cable N at another intermediate stage passes from a loose condition to a stretched condition, FIG. 4, whereby an opening out movement of parts F and G is caused as a consequence of the continuation of the swinging movement of arm H and therefore of arm G. As soon as the vertical alignment of arms G and H is obtained and resulting horizontal positioning of the arm F, and the ends of parts G and H are locked with one another by a clamping device, whereby the stable connection of the parts is positively obtained.

When the capstan is driven in a reverse direction the crane eye hook of the crane is lowered and subsequently hoisted for a conventional handling of a load.

The operation of cable N' is now described, to obtain the possibility of altering the position of the boom from a horizontal position to an inclined position, as shown with chain-dotted lines in FIG. 5. If the end 26 of branch cable N' is engaged in the L-profiled notch 27 of the drum flange, driving of capstan and therefore rotation of the drum will cause an anti-clockwise rotation of the boom as viewed in FIG. 5 to the pre-established position. For rendering this position stable it is only required to engage a hole of a check plate K with a, not represented, pivot or hook fixed to the crane frame.

From the foregoing it will be apparent that by means of a single cable L not only the self-erection of the crane may be obtained but even the vertical handling of the different loads. It is also clear that by means of the same capstan, not only is the self-erection of the crane obtained but also the operative positioning of the boom F obtained, namely a position of the boom other than horizontal.

Claims

What I claim is:

1. A self erecting tower foldable crane to be carried by a truck, of the kind consisting of a slewing crane frame rotatably mounted on said truck, a lower hinged arm, a middle arm and a crane boom, the lower hinged arm being pivoted to the said slewing, the middle arm being articulated at one end to the lower arm and at the opposite end to the crane boom, characterized by the provision

of a capstan fixed to the crane frame

of a main first cable,

of a pulley and a cable arrangement between the crame frame, first cable and tackle means to swing the lower hinged arm

of a tackle means, operated by the main cable by means of said capstan,

of a second cable fixed at one end to the slewing crane frame and at the other end to the crane boom and operating for the self-erecting of the boom.

of an arcuated sector fixed to the said middle arm adjacently to the articulation of the latter with the said lower hinged arm,

and of a third inextensible cable extending around the arcuated sector, one end of the said inextensible cable being fixed to the said slewing crane frame and the opposite end of which being fixed to the said middle arm adjacently to the articulation with the said lower hinged arm, whereby swinging of the hinged lower arm by the capstan by means of the said tackle device causes the self-erection namely the opening out of the said middle arm from the said lower hinged to form a tower for the boom.

2. Crane according to the claim 1. wherein adjacently to the articulation of the said hinged arm with the said middle arm an adjustable spring is fixed with one end to the middle arm, and an L- profiled iron is welded to the lower hinged arm so as to cooperate with the said spring in the aligned position of the said lower hinged arm and middle arm and means are provided for adjusting the reaction of the spring,the compression of the spring in the aligned position of the lower arm and of the middle arm, causing a reaction torque promoting the folding operation of the crane.