US3706285A

US3706285A - Hoisting crane

Info

Publication number: US3706285A
Application number: US107076A
Authority: US
Inventors: Lars Gynt; Lennart Holm
Original assignee: Linden Alimak AB
Current assignee: Linden Alimak AB
Priority date: 1970-01-27
Filing date: 1971-01-18
Publication date: 1972-12-19
Anticipated expiration: 1989-12-19
Also published as: NO138902C; GB1310635A; FI49391C; DE2103667A1; FR2077350B1; SE337089B; FI49391B; NO138902B; CA945515A; CH521920A; FR2077350A1

Abstract

A hoisting crane of the type having a horizontal jib which is pivotally mounted on a vertical tower and supports thereon a movable carriage having a lifting means. The jib is formed of a plurality of detachably couplable modules each of which is formed of at least one upper and at least one lower member extending parallel to each other in the direction of the longitudinal axis of the jib. The longitudinal members of the respective modules all have the same spacing relative to each other so that all of the modules may be constructed with the same overall dimensions on a common jig. The modules which form a jib may have varying strengths to permit the modules which are closer to the pivotal mount on the tower to have a greater load-carrying capacity than those which are disposed toward the free end of the jib, and this is accomplished by having the associated members of some of the modules formed with a greater material cross-section than that of the corresponding members of other of the modules.

Description

United States Patent 11 1 3,706,285 Gynt et al. 1 Dec. 19, 1972 i 1 HOISTING CRANE Primary Examiner-James B. Marbert Assistant Examiner-D. W. Keen {72] inventors: Lars Gynt; Lennart l-lolm, both of vasteras, Sweden Attorney-Sommers 8; Young [73] Assignee: Linden-Alimok AB, Vasteras, [57] ABSTRACT Sweden A hoisting crane of the type having a horizontal jib [22] Filed: Jan. 18, 1971 which is pivotally mounted on a vertical tower and supports thereon a movable carriage having a lifting [2]] Appl' l07076 means. The jib is formed of a plurality of detachably couplable modules each of which is formed of at least [30] Foreign Application Priority Data one upper and at least one lower member extending parallel to each other in the direction of the longitu- Jan. 27, 1970 Sweden ..978/70 dinal axis of the j The longitudinal members of the respective modules all have the same spacing relative 2? 212/144 to each other so that all of the modules may be con I! i e "B666 Structed the same overall dimensions on a Fle d of Search ..l04/124, 14/3, 4, 7, 13, 14, mo jig The modules which form ajib may have vary 212/46 144 ing strengths to permit the modules which are closer to the pivotal mount on the tower to have a greater {56] References cued load-carrying capacity than those which are disposed UNITED STATES PATENTS toward the free end of the jib, and this is accomplished by having the associated members of some of 3. 1104 5/1969 Grider "212/144 the modules formed with a greater material cross-sec- 3l433l459 3/1969 Logan Min/144 tion than that of the corresponding members of other 2,575,564 11/1951 Rinkel r ..212/l44 f the 2,335.522 11/1943 Letourneau t ..212/144 6 Claims, 4 Drawing Figures 7 :4 izagnii iii memmucmm 3.766.285

SHEEI 1 BF 2 LARS GYNT LEN NART HOLM PATENTEDIJENQ I912 3.706.285

SHEET 3 UF 2 LARS GYNT LENNART HOLM I-lOlSTlNG CRANE This invention relates to a hoisting crane adapted particularly for building purposes, comprising a freely projecting jib, which is mounted, for example, on a tower or a derrick and along which can be moved a carriage with a lifting means, which jib has a lattice structure and comprises at least one upper and at least one lower longitudinal frame rod.

A hoisting crane for building purposes usually comprises a tower carrying at its top end portion a horizontal jib. The jib in its turn supports a carriage with a lifting tackle or lifting cables suspended thereon. A carriage of this type being movable along the entire jib, the crane can cover a rectangular working range in a vertical plane.

With increasing demands of the building industry for more rational building methods, the working ranges of the building cranes and, thereby, the length of the jibs have increased. With increasing horizontal operation range for a hoisting crane, the lifting capacity becomes increasingly dependent on the dead weight of the jib. For producing jibs with a low dead weight, the jibs are given a lattice structure, which in many cases is made of a high-grade structural steel.

In conventional cranes, a jib is supported by one or more stay members anchored at the outer half of the jib. The other end of such a stay member usually extends beyond a breaking point located higher than the jib in the extension of the crane tower. A second mounting for such a jib is provided at the connection to the crane tower.

.libs usually have a rectangular or triangular crosssection, with a frame rod placed at each joint of the cross-section. The lower and upper frame rods are connected together by vertical rods and diagonal rods. In

known building cranes, often one and the same frame rod or diagonal rod is subjected either to compressive forces or tensile forces, depending on whether the carriage with load is outside or inside of the point in which the carrying stay member of the jib is anchored at the jib.

For reasons already mentioned, it is desired to utilize all of the material in the jib at optimum for the strength of the jib. in known jibs, however, a substantial increase in weight cannot be avoided, because the main part of the lattice rods is to be dimensioned such as to be able to transfer compressive forces and is calculated with respect to the risk of breaking. Lattice rods in a jib of known design, moreover, when the crane is in operation, are subjected also to alternating loads by both tensile and compressive forces, which at straining crane operations can cause breaks due to fatigue of the rod material. A number of such cases are known.

Building cranes often have jibs with a length of 30-40 m. It is thereby of decisive importance to place the center of gravity of the job near the slewing center, because hereby not only the dead weight moment in the vertical direction, but also the effect of horizontally acting bending moments is reduced which are caused by forces of inertia on the jib at the start and braking of its slewing motion.

The importance of a smaller slewing radius for the gravity point of a jib is easily understood when com sidering that all parts of a jib during the start and braking of its slewing motion are subjected to forces of inertia, the magnitude of which is directly proportional to the product of the dead weight of the part and of the distance to the center for the slewing motion.

In the jib described below. the center of gravity is placed closer to the slewing center than is possible with jibs of known design. Due to the construction of the jib, furthermore, the total surface exposed to wind load is smaller than in known building cranes. This involves, besides, advantages from a dimensioning point of view and improves the operating properties.

The jib, furthermore, is so designed that it comprises a substantially reduced number of rods subjected to compressive forces. Every rod comprised in a jib according to the invention is subjected to only one type of load, either tension or compression, which implies a considerable reduction of the breaking risk resulting from fatigue of the material.

Tower cranes for building purposes are produced in series. It is conventional for the tower to be assembled of construction modules. Heretofore, it has not been possible to manufacture jibs in a corresponding way with modules, due to the reason that, in conventional jibs the loads on a jib, module located at the outer portion of a jib are different from those on a jib module located far inwardly on a jib.

One characterizing feature of the jib according to the invention is that it is supported entirely without outside stay members.

From a production technical point of view, the invention renders possible good flexibility and adaptation to the market.

At a building site, it is often desired to extend the jib of an available building crane. in conventional building cranes, such an extension can be made only in exceptional cases, because the load in the cross-section subjected to the greatest load, which load applies to the mounting of the carrying stay member, increases with the relation between the length of the jib outside of the stay member after the extension and the length of the jib outside the stay member prior to the extension.

In the jib according to the invention, the cross-section subjected to the greatest load always is located at the mounting on the crane tower. Accordingly, the load in the cross-section only increases with the relation between the length of the entire jib after the extension and the length of the entire jib prior to the extension.

This implies for a normal jib extension that the load in the dimensioned cross-section of a jib of known design increases by about 40 while the corresponding load increase for the jib according to the invention only is about 10 From a safety point of view, the invention further involves the advantage that the load moment switch, which must be found at all cranes of this kind, must not be reset after a change of the jib length. Consequently, no new inspection is required either.

The jib in its entirety being dimensioned so as to carry vertical loads without additional stay members, and this implies as a further achievement that the horizontal rigidity is improved substantially over that of known jibs.

Furthermore, the mounting time required for a building crane according to the invention is reduced considerably compared with known building cranes as no stay cables and top supports have to be mounted.

The aforesaid disadvantages are eliminated and the aforesaid advantages are obtained by the hoisting crane according to the invention, which is characterized in that the jib has no outside stay members and in its longitudinal direction is divided into a number of construction modules having different bearing capacity such that the bearing capacity increases from the free end of the jib inwardly, and that the different bearing capacities are obtained by different cross-sectional dimensions of at least one of the rods comprised in the modules.

An embodiment of the crane according to the invention is described below with reference to the accompanying drawing, in which FIG. 1 is a lateral view of a building crane with a jib assembled of construction modules, and

FIGS. 2, 3 and 4 are a lateral view, anend view and a view seen from above, respectively, of a construction module of which an entire jib can be assembled.

The building crane comprises a derrick 2 secured on a foundation 3, a slew base plate 4, a jib 5, which in this embodiment is assembled of five construction modules, a counterweight 6, hoisting machinery 7, a slewing machinery 8, a carriage 9, lifting hook 10, lifting cable 11, and carriage machinery 20.

A construction module comprises upper frame rods 12 and lower frame rods 13, connected together by

rods

14 and 15 arranged perpendicularly to said frame rods and by diagonal rods 16 and 17. The frame rods 12 and 13 as well as the

rods

14, 15, 16 and 17 may be rolled sections or hollow bodies. In FIG. 3, the upper and lower frame rods 12 and 13, respectively, are shown to be square tubes, which may have square or rectangular cross-section. One characterizing feature of a construction module is that all diagonal rods in a lateral projection (FIG. 2) have the same direction.

The drawing shows a construction module having rectangular cross section. The invention, however, allows also for applying construction modules with another cross-section, for example of triangular shape having a point turned upwardly or downwardly. One prerequisite condition, however, is that all diagonals in a lateral projection of the construction module have the same direction.

The upper frame rods 12 are provided with flanges 18 for connecting together the construction modules by bolts. The lower frame rods 13 are provided with guide means comprising guide pins 19 for effecting centering within a frame rod of an adjacent construction module.

The mounting method for a jib according to the invention is simpler than that for conventional jibs because the lower frame rods only transfer compressive forces, so that connections in their usual meaning are not required. What is required is merely a means 19 for centering. This offers the further advantage that the lower frame rods on their outside are entirely smooth and thereby can serve as a runway for the carriage 9.

All construction modules for a jib have the same outer dimension, which is a prerequisite condition for production in series. It is thereby possible to utilize the same production line, the same welding fixtures and other equipment for all jib modules.

All construction modules are so manufactured and iiiiific' iiil'fhifi illit'is iiil'iifiiirlf' fi ciiiifi. tion module, all rods comprise tubes or other hollow bodies, in which case different bearing capacity is obtained in that the outside or inside dimension for all rods of a certain kind is equal while the bearing capacity for different construction modules can be varied by choosing a varying material thickness for the rods.

What we claim is:

I. In a hoisting crane of the type comprising a horizontal jib pivotally mounted on a vertical tower and supporting thereon a movable carriage having a lifting means, the improvement which comprises:

said jib being formed of a plurality of detachably couplable modules each of which comprises at least one upper and at least one lower member which members extend parallel to each other in the direction of the longitudinal axis of the horizontal jib,

said members in each of the respective modules of the jib all having the same spacing relative to each other so as to permit each jib-forming module to be constructed with the same dimensions in a common jib,

some of said jib-forming modules having their as sociated members formed with a greater material cross-section than that of the corresponding members of other of said modules so as to permit an increase in the load-carrying strength of the modules in a direction from the free end of the jib toward its pivotal mounting on said tower without varying the overall cross-sectional dimensions of the several modules forming a complete jib.

2. The crane of claim 1, in which said upper and lower longitudinal members of each module are connected together by substantially vertical rods and diagonal rods, all of said diagonal rods extending in substantially the same direction and sloping downwardly toward the free end of the jib so as to be in tension under load.

3. The crane of claim 1, in which each module is formed of hollow tubes and corresponding tubes of the respectively difi'erent modules having different loadbearing capacity have the same outer dimension.

4. The crane of claim 1, in which each module is formed of hollow tubes and corresponding tubes of the respectively different modules having different loadbearing capacity have the same inner dimension.

5. The crane of claim 1, which further includes a detachable coupling means to couple adjoining ends of said modules, each said coupling means comprising coupling elements at the respective ends of the upper longitudinal members for providing a tension coupling therebetween and coupling elements for the respective ends of the lower longitudinal members which provide longitudinal alignment of the corresponding lower members.

6. A crane according to claim 1, characterized by a smooth transition between the lower members of the modules so that said rods can serve as a runway for the carriage.

t l i i

Claims

1. In a hoisting crane of the type comprising a horizontal jib pivotally mounted on a vertical tower aNd supporting thereon a movable carriage having a lifting means, the improvement which comprises: said jib being formed of a plurality of detachably couplable modules each of which comprises at least one upper and at least one lower member which members extend parallel to each other in the direction of the longitudinal axis of the horizontal jib, said members in each of the respective modules of the jib all having the same spacing relative to each other so as to permit each jib-forming module to be constructed with the same dimensions in a common jib, some of said jib-forming modules having their associated members formed with a greater material cross-section than that of the corresponding members of other of said modules so as to permit an increase in the load-carrying strength of the modules in a direction from the free end of the jib toward its pivotal mounting on said tower without varying the overall crosssectional dimensions of the several modules forming a complete jib.

3. The crane of claim 1, in which each module is formed of hollow tubes and corresponding tubes of the respectively different modules having different load-bearing capacity have the same outer dimension.

4. The crane of claim 1, in which each module is formed of hollow tubes and corresponding tubes of the respectively different modules having different load-bearing capacity have the same inner dimension.