Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
  • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
  • B66C23/54—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes with pneumatic or hydraulic motors, e.g. for actuating jib-cranes on tractors

Definitions

• the present invention relates to a crane having a post and, articulated thereto, a jib which is pivotable in relation to the post by means of a hydraulic cylinder whose one end is articulated to the crane post and whose opposite end is articulated to the jib.
• a hydraulic cylinder whose one end is articulated to the crane post and whose opposite end is articulated to the jib.
• Such a design is both inexpensive and simple for the post as such, but involves a hard-to-solve problem with respect to the leverage required between, on the one hand, the conventionally fixed main articulation connect ⁇ ing the jib to the crane post and, on the other hand, the movable articulation connecting the hydraulic cylinder to the jib. If the lateral distance between these articula ⁇ tions, i.e. the leverage, is short, this restricts the lifting moment that a given hydraulic cylinder is able to apply to the jib when lifting a load.
• the modified and inclined crane post is both complicated and expensive to manufacture, and the design including a special bump cylinder is also relatively expensive and, in addition, involves an extra operation for actuating the bump cylin ⁇ der, which further complicates the operation of the crane in its entirety.
• the present invention aims at obviating the above inconveniences and drawbacks by providing a crane which, at least in some respects, meets such requirements as were previously deemed incompatible.
• the basic object of the invention is to provide a crane in which the post can be a simple and straight hollow section, at the same as the requisite leverage between the main articulation and the cylinder articulation is considerable, but which does not therefore need any special bump cylinders.
• Another object of the invention is to provide a crane which is low-built and compact when parked, but which nevertheless is able to reach high up with its tool.
• a further object of the invention is to provide a crane which has substan- tially the same lifting power within the major part of it working range. Also, the invention aims at providing a crane whose working range is larger than that of prior-ar cranes.
• the jib is connected to the crane post by at least two link means which are of different length and of which a short first link is connected to the post by mean of a first articulation and connected to the jib by means of a second articulation, and a long second link is con ⁇ nected to the post by means of a third articulation and connected to the jib by means of a fourth articulation; that the first and third articulations of the post are laterally spaced apart, more precisely in such a manner that the first articulation is closer to the jib side of the post than is the third articulation; and that the second and fourth articulations of the jib are spaced apart not only in the axial extension of the jib but also in a direction perpendicular to said axial extension, the long second link mechanically guiding the point of connec ⁇ tion of the hydraulic cylinder to the jib in a first, sub
• FIG. 1 is a side view of the crane according to the invention, the jib being in an inactive or park ⁇ ing position
• FIG. 2 is a partial side view of the crane, the jib being illustrated in two different active posi ⁇ tions, namely one position in which the jib is directed substantially horizontally from the crane post and another position in which the jib is directed in a substantially vertical direction up from the crane post
• FIG. 3 is a top plan view illustrating parts of the crane shown in Fig. 2. Description of the Preferred Embodiment
• the crane according to the invention has a post or body 1 and, connected thereto, a jib 2 which is pivotable in relation to the post by means of a hydraulic cylinder 3 which, in technical language, is termed air cylinder.
• the jib 2 is also connected to an outer boom 4 which in turn is con ⁇ nected to a special hydraulic cylinder 5 by means of a system of links 6, 6'.
• the crane post 1 is connected to a supporting girder 8 by means of a live ring 7 or the like, which allows turning the post to optional angular positions in relation to the supporting girder 8.
• the girder 8 may in turn be mounted on a vehicle chassis indicated by frame side members 9, 9', e.g.
• the supporting gir- der 8 may advantageously be equipped with extendable sup ⁇ porting legs 10 at its opposite ends.
• a platform 11 having a chair 12 for the crane operator can be mounted on the post 1.
• the main part of the jib is made up of a hollow sec- tion 13 of square cross-section. Apart from two opposite side surfaces or side flanges, the section 13 has two opposite surfaces or flanges 14, 15, hereinafter termed upper side and lower side, respectively.
• Figs 2 and 3 illustrate, together with Fig. 1, how the jib 2 is connected to the crane post 1 by means of two link means of which one is shorter than the other.
• the first link means includes two separate link halves or link arms 16, 16'
• the second link means similarly includes two spaced-apart link halves or link arms 17, 17'.
• the short link arms 16, 16' of the first link means are connected to the post 1 by means of a first articulation 18 and connected to the jib by means of a second articulation 19.
• the long link arms 17, 17' are connected to the post by means of a third articulation 20 and connected to the jib by means of a fourth articulation 21.
• the two articulations 18, 20 which are associated with the post 1 are laterally spaced apart and located in one and the same horizontal plane close to the top of the post 1.
• the first articulation 18 is closest to the jib side of the post, whereas the third articulation 20 is located at a dis- tance therefrom.
• the articula ⁇ tion 20 is a pivot shaft (see Fig. 3) arranged on one or more brackets 22 projecting from the post side opposite to the jib.
• the pivot shaft 20 is connected to the two link arms 17, 17' at its opposite ends, suitably in such a manner that the link arms are mounted on the pivot shaft, it being also conceivable to have a rigid connec ⁇ tion between the link arms and the pivot shaft which may be mounted on the brackets 22.
• the two side members 23, 23' which are associated with the second and fourth arti ⁇ culations 19, 21.
• the two side members which are iden ⁇ tical but reversed, taper to a pointed portion 24.
• the third articulation 19 is arranged at the pointed portion 24 of each side member.
• the fourth articulation 21 is associated with a side-member portion 25 projecting down ⁇ wards a distance below the underside 15 of the box section 13.
• the third articulation 19 is located close to a central longitudinal axis through the jib, while the fourth articulation 21 is laterally offset a considerable distance in relation to this longitudinal axis.
• the two articulations 19 and 21 are axially offset in relation to one another in such a manner that the articulation 19 is close to the jib end, while the articulation 21 is offset a considerable distance inwards on the jib.
• the air cylinder 3 is connected to the post 1 by means of a fifth articulation 26 arranged as low down as possible on the post.
• the air cylinder 3 is, in the embodiment shown, connected to the jib 2 by means of the articulation 21 connecting the link arms 17, 17' to the jib.
• the link arms 17, 17' are more than twice as long as the link arms 16, 16', as based on the distance between the articulation pairs of each link means.
• the crane operates as follows. When the jib 2 is to be swung out and up from the parking position shown in Fig. 1, the piston rod 27 (see Fig. 2) is pushed out of the cylinder member 28 while the hydraulic cylinder in its entirety is lengthened by pump ⁇ ing oil into the piston chamber of the cylinder.
• the lengthening of the hydraulic cylinder causes the link pair 17, 17' to pivot about the articulation 20, while the articulation 21 mechanically follows an arcuate path about the articulation 20, at the same time as the link pair 16, 16' starts to pivot about the articulation 18 and the articulation 19 follows an inner and arcuate path of move ment having a smaller radius than the first-mentioned path.
• the jib during the continued lengthening of th hydraulic cylinder reaches the position of Fig.
• the horizontal distance between the articula ⁇ tions 20 and 21 is maximal, which means that considerable lifting moment can be applied to the jib when needed most During this pivotal movement (70 to 80°) from the parking position to the horizontal position, the jib is raised a distance which approximately corresponds to the distance between the articulations 18, 19 in that the link arms 16 16' are simultaneously caused to pivot about the articu- lation 18 so that the articulation 19 is positioned above the top of the post.
• the advantages of the invention leap to the eye.
• the point of application of the hydrauli cylinder on the jib can, without the use of any special bump cylinders, be moved to a position horizontally remov ⁇ ed from a post articulation, where a maximum lifting moment is applied to the jib when needed most. Since both the jib and the articulation which the jib pivots about are successively raised during the upwardly directed pivo- tal movement, the crane can be of compact construction and still have a large working range, while requiring minimum parking space in relation to its working range.
• the crane according to the invention has, in practice, a working range of 160-170°, to be compared with the working range of about 90° of conventional cranes of the same type.
• a further advantage of the crane according to the invention is that in particular the long link arms 17, 17' serve to stabilise the jib when the crane post " is turned to different angular positions in relation to the support ⁇ ing girder 8.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Jib Cranes (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (3)

Cited By (4)

Citations (2)

• 1990
  • 1990-08-29 SE SE9002765A patent/SE466912B/sv not_active IP Right Cessation
• 1991
  • 1991-08-22 WO PCT/SE1991/000555 patent/WO1992004271A1/en unknown
  • 1991-08-22 AU AU85325/91A patent/AU8532591A/en not_active Abandoned

Patent Citations (2)

Non-Patent Citations (1)

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