Patent Publication Number: US-6669038-B1

Title: Self-propelled crane

Description:
FIELD OF THE INVENTION 
     This invention relates to the self-propelled cranes and more particularly to self-propelled cranes with non-telescopic boom. 
     BACKGROUND OF THE INVENTION 
     The various types of cranes are well known. In order to lift the heavy and most important large-size load are used the cranes and derricks with luffing jib and/or cranes with a telescopic main boom. Some cranes for increasing of the boom luffing characteristics use a luffing jib section in addition to the telescopic boom, as it is mentioned, for example, in the U.S. Pat. No. 4,063,649. Accordingly to this patent the mobile crane has a telescopic boom comprising a lower section, an intermediate section slidable telescopically within the upper end of the lower section and an upper section slidable telescopically within the upper end of the intermediate section. Extension means such as hydraulic rams are provided to position the intermediate section with respect to the lower section and the upper section with respect to the intermediate section so that the overall length of the telescopic boom may be adjusted to any desired value between a maximum and a minimum limit. 
     The lower end of the boom intermediate section is pivoted to a horizontal base unit so as to permit luffing movement of the boom. 
     The base unit is mounted upon a road vehicle chassis and is arranged for rotation with respect to the chassis about a vertical axis on a slewing center. 
     For basic duties of the crane, a load is suspended by a hoist rope which passes over a sheave at the outer end of the boom upper section to a winding drum. By varying the extension of the boom and/or the luff angle, the horizontal distance between the slewing center and the hoist rope can be varied so as to permit the lifting of loads located within a range of radius of action from the slewing center. 
     For fly duties of the crane in order to increase a range of radius of action from the stewing center for lager size load lifting, is used an additional luffing jib (fly jib), which is secured to the outer end of the boom intermediate section and the hoist rope (cable) passes over a sheave at the fly jib outer end. For any combination of telescopic boom extension and fly jib the distance between the slewing center and the hoist rope new position at the end of the fly jib is greater than the corresponding value of the distance between the slewing center and the hoist rope position at the end of boom upper section. 
     Such modification (supplementary equipment) provides increasing of boom-out, but leads to decreasing of the lifting load weight considering weak and non-moored construction of the fly jib, and also requires the reinstallation operations for crane basic duties and for crane fly duties. The crane supplementary equipment presented in the U.S. Pat. No. 4,673,093 is for mooring a crane and is intended to provide a heavy load lifting by the assembly of interconnected guy wires (cable) between a gay mast, which is not connected to a luffing jib and not directly connected to a main boom, and long, massive stationary crane foundation (e.g. pontoon). The possibility to lift large-size load in such crane is provided by the standard luffing jib. 
     These types of cranes have complex mooring system comprising the separate gay cable and luffing cable, requiring additional hoist blocks and frames and the described improvements by the mentioned U.S. Pat. No. 4,673,093 is not applicable for the mobile cranes, which has mostly a boom and not provided by the expensive luffing jib system. 
     As has been mentioned above, the most of the small and medium self-propelled cranes (mobile cranes) have a boom and do not include a luffing jib, being unable to lift a large-size load, as shown, for example, on FIG. 1 (on the drawing is presented a hypothetical/conventional lifting of the load). 
     Some cranes have a need to arrange the large-size load for lifting. The hoisting arranging equipment for large-size load is described in the U.S. Pat. No. 5,314,262. According to the invention, a supplemental equipment for load arrangement includes two motor driven cable drums, fixed cable points associated with the load arranged on the frame of the load, cable rollers arranged on a roller support, as well as hoisting cables guided between the cable fixed points and the cable drums. The cable drums are of a double-thread design wherein each of the cable drums feeds of two cables. The cable drums, together with their drives, are supported on the load in parallel and offset by a drum diameter. The distance between the cable supported by a first drum and cable supported by a second drum approximately corresponds to a spacing distance between a first set of rollers and second set of rollers on the roller support when the cable drum is fully wound with cable (the roller support and spreader are in an upper most position). The distance between the cable fixed points of cables from the first drum and the fixed points of cables from the second drum likewise corresponds approximately to the distance between the first set of cable rollers and the second set of cable rollers. The first set of cables on the first drum and the second set of cables on the second drum run off the drum in an inward direction (the first set of cables move inwardly, towards the second set of cables and the second set of cables move inwardly towards the first set of cables as they run off during lowering). 
     Such load arranging supplementary equipment is complex and expensive. 
     Thus, the known small and medium self-propelled cranes can not provide the lifting of heavy and large-size loads. 
     OBJECT AND ADVANTAGES OF THE INVENTION 
     Accordingly, several objects and advantages of the present invention are to provide an improved self-propelled crane to lift the heavy and large-size loads. 
     It is another object of the invention to increase the self-propelled crane possibility to lift the loads with the higher weights. 
     It is still another object of the invention to provide the increased the luffing of the small and medium self-propelled cranes. 
     It is further object of the invention to increase the self-propelled crane possibility to lift the loads with the larger sizes. 
     It is still further object of the invention to provide the horizontal level of the lifting loads. 
    
    
     DESCRIPTION OF THE DRAWING 
     In order that the invention and the manner in which it is to be performed may be more clearly understood, embodiments thereof will be described by way of example with reference to the attached drawings, of which: 
     FIG. 1 is a simplified representation of the self-propelled crane deficiency (prior art). 
     FIG. 2 is a simplified drawing of the improved self-propelled crane. 
    
    
     SUMMARY OF THE INVENTION 
     This invention provides a possibility to lift the heavy and large-size (oversize) loads. An improved self-propelled crane includes a mobile unit as a base unit, which carries a pivoting platform, a traverse, a boom, the bottom of which is by a hinge connected to the platform and the upper end of a boom is attached to a luffing arm. The upper end of the boom has the first hoist cable (rope) roller and another end of the luffing arm has the second hoist cable roller. The first hoist cable is connected to a crane hook mechanism. The traverse, comprising a truss connected by the traverse hinge to a frame which is by the slings connected to the load, is suspended on the second hoist cable passing via the traverse rollers to the crane hook mechanism. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An improved self-propelled crane includes a mobile unit  1  as a base unit, which carries a pivoting platform  2 , a boom  3 . The bottom of the boom  3  is by the hinge connected to the platform  2  and the upper end of a boom  3  is attached to a luffing arm  4 . The upper end of the boom  3  has the first hoist cable (rope) roller  14  and another end of the luffing arm has the second hoist cable roller  15 . The mechanism, providing the lifting operations, includes the electrical motors (not shown) respectively coupled with the first  21  and second  22  winches, which are respectively coupled with the first  5  and second  6  hoist cables. The inner end of the first hoist cable  5  is connected to the first winch and the outer end of the first hoist cable  5  is connected to a crane hook mechanism  13 . The block  19  can be installed between a boom roller  14  and hook mechanism  13  (first nook mechanism). The traverse  16 , comprising a truss  7  connected by the traverse hinge  17  to a frame  8  which is by slings  10  connected to the load  11 , is suspended on the second hoist cable  6  passing via the traverse rollers  12  to the hook mechanism  13 . The inner end of the second hoist cable  6  is connected to the second winch and the outer end of the first hoist cable  6  is coupled to a crane hook mechanism  13 . The improved self-propelled crane includes at least one of a plurality of second hoist cable gay  20 , the bottom end of which is connected to the boom  3  and the upper end comprises a roller (not shown). The bottom end of the second hoist cable gay  20  can be connected to the boom  3  by the hinge (not shown). The set of traverse rollers  12  (on FIG. 2 the set of traverse rollers  12  is presented by two rollers in line) can, for example, include at least one roller located at the traverse center or a plurality of the rollers, for instance,  3  rollers in line and more, depending on the weight of load and strength of the truss  7 . The traverse hinge  17  is located along axis  9  of the traverse gravity center. The connection of the “free” (outer) end of the second hoist cable  6  to the first hoist cable hook  13  can, for example, be provided by the kink clipped by the removable bolt-brace connector  18  (or by gripping connection, etc.). 
     The improved self-propelled crane operates as follow. The self-propelled crane can operate in three modes depending on the crane winches activity. According to the first mode, the load lifting is provided by the first winch  21  and first hoist cable  5 . In this mode the first winch  21  is active and, for example, when the first hoist cable  5  goes up, the traverse  16  is rolled on the traverse rollers (blocks)  12  going up thereby lifting the load  11 . In compliance with the second mode, second winch  22  is active and when the second hoist cable  6  goes up the traverse  16  is rolled on the traverse rollers  12  going up thereby lifting the load  11 . The third mode is related with the both winches activity. In this mode the first  5  and second  6  hoist cables go up, pulling up the traverse  16  connected to the load  11 . Also possible variation of the crane winches activity, for example, the winches activity in sequence. 
     Thus, by an improved self-propelled crane provides the lifting of the heavy and large-size loads. 
     CONCLUSION, RAMIFICATION AND SCOPE 
     Accordingly the reader will see that, according to the invention, I have provided a self-propelled crane with high efficiency for lifting of heavy and large-size loads . An improved crane has various possibilities, considering activities of two hoist cables in synchronous and independent regimes. 
     While the above description contains many specificities, these should not construed as limitations on the scope of the invention, but as exemplification of the presently-preferred embodiments thereof. Many other ramifications are possible within the teaching to the invention. For example, an improved self-propelled crane can lift two different non-oversize loads at the same time or to provide the vertical rotation of the load in the suspended position. 
     Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, and not by examples given.