Mast arm segment for a concrete pump

Abstract

The invention relates to a boom-arm segment, comprising an upper chord (33), a lower chord (34) and two side parts (35, 36) connecting the upper chord (33) and the lower chord (34). The boom-arm segment (30) comprises a hinge connection (62) which defines a pivot axis (74) for a pivot connection between the boom-arm segment (21) and an adjacent structure (20), wherein: the pivot axis (74) is located below the plane (63) of the lower chord (34); a transition piece (64) is located between the lower chord (34) and the hinge connection (62), and the connection (65) between the transition piece (64) and the lower chord (34) is spaced apart from the adjacent end (61) of the lower chord (34); the transition piece (64) is enclosed between a first reinforcement part (40) and a second reinforcement part (70) which laterally adjoin the transition piece (64); the reinforcement parts (40, 70) each have a lower edge (69) which extends from the hinge connection (62) to the lower chord (34); and the lower edges (69) enclose an angle (68) with the plane (63) of the lower chord (34) that is smaller than the angle (67) which the transition piece (64) encloses with the plane (63) of the lower chord (34).

Description

[0001] The invention relates to a boom arm segment for a concrete pump.

[0002] With a concrete pump boom arm, a concrete pump's delivery line can be directed so that the liquid concrete pumped by the concrete pump is discharged in an area remote from the concrete pump. A concrete pump boom arm is typically composed of a plurality of boom arm segments. When unfolded, the boom arm segments together make up the length of the boom arm. When folded, the boom arm segments are folded into a compact state to facilitate transport.

[0003] Mast arm segments are known, for example, from the publications CN 205 036 090 U and CN 110 984 578 B.

[0004] Concrete pumps typically deliver liquid concrete intermittently, meaning the boom arms are subjected to considerable dynamic loads. In addition, the boom arm segments can be folded differently when the concrete pump is in operation, depending on the distance from the concrete pump at which the liquid concrete is to be discharged. This results in the tensile and compressive loads acting on a boom arm segment in completely different directions depending on the boom arm's operating condition. For these reasons, the boom arm segments of a concrete pump are subjected to specific loads during operation.

[0005] The invention is based on the object of presenting a concrete pump boom segment that is lightweight and cost-effective to manufacture. Based on the cited prior art, this object is achieved by the features of the independent claims. Advantageous embodiments are specified in the subclaims.

[0006] The boom arm segment according to the invention comprises an upper chord, a lower chord, and two side parts connecting the upper chord and the lower chord. The boom arm segment comprises a hinge connection that defines a pivot axis for a pivot connection between the boom arm segment and an adjacent structure. The pivot axis is arranged below the plane of the lower chord. A transition piece extends between the lower chord and the hinge connection. A first connection is formed between the transition piece and the lower chord. The first connection is spaced from the end of the lower chord. This information refers to the end of the lower chord adjacent to the transition piece, i.e., closest to it; the transition piece is also spaced from the opposite end of the lower chord. The transition piece is enclosed between a first reinforcement part and a second reinforcement part, which are laterally adjacent to the transition piece.The reinforcement pieces each have a lower edge extending from the hinge connection to the bottom chord. The lower edges form an angle with the plane of the bottom chord that is smaller than the angle formed by the transition piece with the plane of the bottom chord.

[0007] The invention recognizes that the transition piece between the lower chord and the hinged connection provides a particularly advantageous way of transferring the forces acting in the area of ​​the hinged connection into the mast arm segment. To avoid stress peaks at the transition between the transition piece and the lower chord, the transition is arranged at a distance from the end of the lower chord.

[0008] The information above and below refers to the state of the mast arm segment shown in the drawings. The directions assume that the bottom chord is horizontal. This does not restrict the subsequent installation position of the mast arm segment; in particular, installation positions rotated by 90° or 180° from the state shown in the figures are possible.

[0009] The lower chord can extend from an end adjacent to the joint connection along a straight line toward an opposite end of the boom arm segment (longitudinal direction). The end of the boom arm segment adjacent to the joint connection can be the proximal end. The plane of the lower chord is defined by the longitudinal direction of the lower chord and the dimension parallel to the pivot axis of the joint connection. If the lower chord does not extend over the entire length of the boom arm in one plane, the plane of the lower chord is defined by a section of the lower chord adjacent to the joint connection.

[0010] It is possible for the lower chord to also extend transversely in the plane of the lower chord. Preferred embodiments are those in which the lower chord has a shape that extends out of the plane of the lower chord in the transverse direction. For this purpose, the lower chord can have one or more bends or be provided with one or more folded edges. The direction of the edges / bends can be parallel to the longitudinal direction of the mast arm segment, resulting in a shape that extends out of the plane in the transverse direction. The lower chord can have a shape that is curved in the transverse direction, for example by folding the lower chord so that the sum of the folds corresponds to a curvature. The curvature can be oriented such that the distance between the pivot axis of the articulated connection and a central region of the lower chord is smaller than the distance between the pivot axis and a peripheral region of the lower chord.The plane of the bottom chord is defined by the area of ​​the bottom chord that is closest to the hinge connection. As an alternative to a curved shape, edges that are bent in opposite directions are also possible, forming one or more corrugations in the bottom chord.

[0011] Particularly in the case of a bottom chord that is not flat in the transverse direction, it is advantageous if this is straight in the longitudinal direction, i.e. if it does not extend out of the plane of the bottom chord in the longitudinal direction. If there is no overlap between the plane of the bottom chord and the articulated connection, a direct connection between the bottom chord and the articulated connection arranged below the plane of the bottom chord is not possible. The invention proposes creating this connection using a transition piece. Although this requires the processing of an additional component during manufacture of the mast arm segment and requires additional work steps compared to designs in which the articulated connection can be connected directly to the bottom chord, the solution has proven to be advantageous overall.

[0012] The boom arm segment is designed to be pivotally connected to an adjacent structure via a pivot joint. The adjacent structure can be another segment of the boom arm or a base frame of the concrete pump. The pivot joint is formed by a first pivot connection, which is an element of the boom arm segment, and a second pivot connection, which is an element of the adjacent structure separate from the boom arm segment. The position of the pivot axis is defined by the pivot connection of the boom arm segment.

[0013] The joint connection may comprise a joint bore, wherein the axis of the joint bore corresponds to the pivot axis. The joint connection may comprise a structure within which the joint bore is formed. For example, the joint connection may be a piece of pipe within which the joint bore extends. The joint connection may form a receptacle for a joint pin.

[0014] The transition piece extends diagonally downwards from the first connection, which connects it to the bottom chord, toward the hinged connection. This creates an angle between the transition piece and the plane of the bottom chord. The transition piece can form an angle between 5° and 50°, preferably between 10° and 40°, with the plane of the bottom chord. Angles outside this range are less favorable for force transmission between the bottom chord and the hinged connection.

[0015] The transition piece can extend along a straight line between the bottom chord and the articulated connection. Transversely, the transition piece can also be straight, so that the transition piece has an overall flat shape. Alternatively, the bottom chord can have one or more bends or be provided with one or more folds. The direction of the edges / bends can be parallel to the longitudinal direction, resulting in an out-of-plane shape in the transverse direction. The transition piece can have a curved shape in the transverse direction, for example, by folding the bottom chord so that the sum of the folds corresponds to a camber. In the lateral dimension, the transition piece can extend over the entire width of the bottom chord that the bottom chord has in this section.

[0016] A second connection can be formed between the transition piece and the articulated connection. The distance between the second connection and the plane of the lower chord can be greater than the distance between the pivot axis and the plane of the lower chord. Alternatively, the transition piece can also be arranged so that there is no direct connection between the transition piece and the articulated connection. In this case, the transition piece can comprise a section that is arranged below the articulated connection. Adequate force transmission between the transition piece and the articulated connection can be ensured, for example, by arranging both the transition piece and the articulated connection between two reinforcing parts, so that the force transmission between the articulated connection and the transition piece takes place through the reinforcing parts.In one embodiment, the transition piece connects to a cover plate that forms a connection to the upper chord at the end of the mast arm segment.

[0017] The transition piece can be made of sheet steel. The transition piece can be welded to the bottom chord and / or the hinged connection. The transition piece can be designed so that it is flush with the hinged connection and / or the bottom chord across its entire width. The welded connection to the hinged connection and / or the welded connection to the bottom chord can extend across the entire width of the transition piece.

[0018] The distance between the pivot axis of the articulated connection and the plane of the bottom chord can be so large that the plane of the bottom chord does not intersect the joint hole of the articulated connection. In particular, the distance between the pivot axis of the articulated connection and the plane of the bottom chord can be so large that the plane of the bottom chord does not intersect the structure of the articulated connection.

[0019] The mast arm segment comprises a reinforcement member extending from the joint connection to the lower chord. The reinforcement member may extend beyond the lower chord into a side portion of the mast arm segment. The reinforcement member may be designed to transfer forces acting on the joint connection into the mast arm segment. The reinforcement member comprises a lower edge extending from the joint connection to the lower chord. The lower edge forms an angle with the plane of the lower chord that is smaller than the angle formed by the transition piece with the plane of the lower chord. The difference between the angles may, for example, be between 2° and 20°, preferably between 5° and 10°.

[0020] Relative to a given longitudinal position of the bottom chord, the distance between the lower edge of the reinforcement member and the plane of the bottom chord may be greater than the distance between the transition piece and the plane of the bottom chord. This may apply in particular to the area where the transition piece is connected to the hinged connection. This may also apply over the entire length of the transition piece. The transition piece may be welded to the reinforcement member along its length. A design in which the transition piece is spaced from the lower edge of the reinforcement member has the advantage that the forces exerted by the hinged connection can be distributed more evenly.

[0021] The transition piece is enclosed between a first reinforcement member and a second reinforcement member, which are laterally adjacent to the transition piece. The reinforcement members may also enclose the hinge connection and / or a section of the bottom chord. Both reinforcement members may have the aforementioned features.

[0022] The end of the bottom chord may be enclosed between the reinforcement members. The end of the bottom chord may be spaced from an edge of the reinforcement member that is an extension of the bottom chord.

[0023] For the purpose of force distribution according to the invention, the connection between the transition piece and the lower chord is at a distance from the end of the lower chord, i.e. there is a section of the transition piece that is arranged below the lower chord. The section of the transition piece arranged below the lower chord can make up at least 5%, preferably at least 10%, more preferably at least 30% of the length of the transition piece. This information refers to the area of ​​the lower chord in which the proximal end of the lower chord is at the greatest distance from the junction with the transition piece. This can be a lateral area of ​​the lower chord with which the lower chord runs into the reinforcement parts. A central area of ​​the lower chord, on the other hand, can be cut out and set back. Preferably, the set-back area is also at a distance from the connection between the transition piece and the lower chord.

[0024] The use of such a transition piece is particularly useful when the side parts of the mast arm segment are beveled inward. It is then possible to connect the two reinforcement pieces, which sandwich the transition piece, to the side parts as described below.

[0025] The side part of the mast arm segment can have a bevel such that a central section of the side part is laterally offset inward relative to an edge section of the side part. Between the edge section and the central section, there can be a transition section that forms a connection between the edge section and the central section. The reinforcement part can have a material thickness that bridges the lateral offset between the edge section and the central section.

[0026] The reinforcement part can be butt-welded to the transition section. In the areas of the edge section and the central section adjacent to the transition section, a direct connection can also be created between the reinforcement part and the side part. The connection between the side part and the reinforcement part can be designed as a welded connection. The welded connection can be butt-welded over the entire length of the connection between the reinforcement part and the side part, so that an end face of the reinforcement part is welded to an end face of the side part. It is also possible for the welded connection to comprise butt-welded and overlap-welded sections. The butt-welded sections of the welded connection can comprise the connection to the transition section of the side part as well as other sections.

[0027] In one embodiment, the reinforcement member is butt-jointed to the edge portion of the side member and overlapped to the central portion of the side member. The edge portion of the side member may be adjacent to the upper chord or the lower chord of the mast arm segment. The reinforcement member may be connected to the central portion of the side member by a weld extending along a portion of a peripheral edge of the reinforcement member.

[0028] The side part can be designed to include an upper edge portion adjacent to the top chord and a lower edge portion adjacent to the bottom chord. The reinforcement part can be dimensioned to be butt-connected to both the transition portion between the central portion and the upper edge portion and the transition portion between the central portion and the lower edge portion. Additionally, the reinforcement part can be butt-connected to both the upper edge portion and the lower edge portion. The reinforcement part can be in an overlapping connection with the central portion. An upper end of the reinforcement part can terminate in the upper edge portion.

[0029] The reinforcement part can comprise an end region that tapers within the side part. The end region can taper in the side part. The end region can overlap with the side part. The tip of the end region can taper in the central section of the side part. The tip is the outermost point of the end region, regardless of whether the end region tapers to a point there or has a different shape, e.g., is rounded. The tip of the end region can be arranged close to the neutral fiber of the mast arm segment, which means that the distance between the tip of the end region and the nearest belt is at least a factor of 2, preferably a factor of 3, more preferably a factor of 5 greater than the distance between the tip and the neutral fiber.

[0030] The joint connection can form a proximal joint receptacle of the boom arm segment. A receptacle for a joint pin can be formed in the reinforcement part. A joint lever, to which a hydraulic cylinder can be connected, can be connected. The hydraulic cylinder has the function of pivoting the boom arm segment relative to an adjacent structure, in particular relative to an adjacent boom arm segment. The joint lever can be connected to the reinforcement part via a pivot connection.

[0031] The boom arm segment may include a mounting bracket for a conveyor line holder. The mounting bracket may extend transversely through the boom arm segment and form a cross connection between the opposing side panels of the boom arm segment. For example, the mounting bracket may be welded to each of the side panels. The mounting bracket may extend between the central sections of the opposing side panels. In this way, the mounting bracket may provide additional protection against the side panels of the boom arm segment deflecting sideways under load. The connection to the side panels allows the forces exerted by the attached elements to be effectively transmitted to the side panels.

[0032] On one side of the boom arm segment, the fastening receptacle can protrude beyond the side part. On this side, the fastening receptacle can be designed so that a holder for the conveyor line can be connected. For example, blind holes can be provided for a screw connection. However, it is also possible for the holder to be welded to the fastening receptacle, for example. In one embodiment, the boom arm segment comprises a holder for a conveyor line connected to the fastening receptacle and / or a conveyor line connected to the fastening receptacle. Furthermore, hydraulic lines can be connected to the boom arm segment, via which, for example, hydraulic devices for folding and unfolding the boom arm can be operated.

[0033] The mast arm segment can comprise a plurality of such fastening receptacles, in particular at least two fastening receptacles, preferably at least three fastening receptacles, more preferably at least four fastening receptacles. The fastening receptacles can be substantially evenly distributed over the length of the mast arm segment. One or more of the fastening receptacles can be connected to a reinforcement part.

[0034] The conveyor line can extend the length of the boom arm segment. For connection to a conveyor line of an adjacent boom arm segment, the conveyor line can comprise a joint part at one or both of its ends, which is designed to form a pivotable connection to a conveyor line of an adjacent boom arm segment. The pivot axis defined by the joint part can be coaxial with the pivot axis of the joint connection and thus coaxial with the axis of the boom arm pivot joint. The conveyor line can be arranged laterally of the boom arm segment.This is an essential boundary condition for the design of boom arm segments because, on the one hand, it must be possible to bring the boom arm segments of a boom arm into a folded state despite the parallel arranged conveyor line and, on the other hand, because there is not an unlimited amount of space available in the lateral direction without exceeding the permissible width of road-legal vehicles.

[0035] The invention also relates to a concrete pump boom arm having a plurality of boom arm segments, wherein at least one of the boom arm segments is designed according to the invention. A pivot joint is formed between each two adjacent boom arm segments. The axis of the pivot joint can be oriented such that it extends through both side parts of the boom arm segment, wherein the two side parts are preferably intersected at right angles or form an angle of less than 10°, preferably less than 5°, with this direction. The belt surfaces can extend parallel to the pivot axis.

[0036] The joint may comprise a first articulated lever pivotally attached to a first boom arm segment. The joint may comprise a second articulated lever pivotally attached to the second boom arm segment and also pivotally attached to the first articulated lever. A hydraulic cylinder may extend from the first boom arm segment to the first articulated lever, such that a lifting movement of the hydraulic cylinder is translated into a pivoting movement between the boom arm segments. The hydraulic cylinder is preferably attached to the first articulated lever beyond the second articulated lever, as viewed from the first boom arm segment.

[0037] The concrete pump boom arm can comprise a delivery line for a thick material, in particular fresh concrete, which extends along the boom arm. Each segment of the boom arm can be assigned a segment of the delivery line. Adjacent segments of the delivery line can be connected to one another via a joint, with the joint axis preferably being coaxial with the joint connecting the associated boom arm segments. The individual segment of the delivery line can be designed as a rigid pipeline.

[0038] The invention is described below by way of example with reference to advantageous embodiments in the accompanying drawings. They show: Fig. 1: a concrete pump vehicle with a boom arm in the folded state; Fig. 2: the concrete pump vehicle from Fig. 1 with the mast arm unfolded; Fig. 3: a mast arm segment according to the invention; Fig. 4: a joint between two mast arm segments; Fig. 5: the proximal end of the mast arm segment made of Fig. 3 in enlarged view; Fig. 6: a section of the mast arm segment from Fig. 3 in enlarged view; Fig. 7: the distal end of the mast arm segment from Fig. 3 in an enlarged view; Fig. 8: a mounting bracket for the mast arm segment from Fig. 3 in enlarged view; Fig. 9: the fastening receptacle from Fig. 8 in a different perspective; Fig. 10: the proximal end of the mastoid segment from Fig. 5 in perspective view; Fig. 11: the distal end of the mast arm segment from Fig. 7 in perspective view; Fig. 12: a cross section along line AA in Fig. 5 ; Fig. 13: a view from below of the proximal end of the mastoid segment from Fig. 5 ; Fig. 14: the mast arm end from Fig. 13 without lateral reinforcement part; Fig. 15: the mast arm end made of Fig. 13 in a view from below; Fig. 16: the mast arm end from Fig. 14 in a view from below.

[0039] One in Fig. 1 The truck 14 shown is equipped with a concrete pump 15, which conveys liquid concrete from a pre-filling container 16 through a delivery line 17. The delivery line 17 extends along a boom arm 18, which is rotatably mounted on a slewing ring 19. The boom arm 18 comprises three boom arm segments 20, 21, 22, which are connected to one another in an articulated manner. By pivoting the boom arm segments 20, 21, 22 relative to one another via the joints, the boom arm 18 can be switched between a folded state ( Fig. 1 ) and an unfolded state ( Fig. 2 ). The delivery line 17 extends beyond the distal end of the third boom arm segment 22 so that the liquid concrete can be applied in an area remote from the concrete pump 15.

[0040] Depending on the boom arm's pivoting position, the loads act on boom arm segments 20, 21, and 22 in very different directions. Furthermore, the boom arm is subjected to high dynamic loads due to the intermittent delivery of liquid concrete.

[0041] The pivot joints between the boom arm segments 20, 21, 22 are designed to allow a large pivot angle. In the folded state, the boom arm segments 20, 21, 22 are essentially parallel to each other and form a small angle between them. In the unfolded state according to Fig. 2 the mast arm segments 20, 21, 22 extend approximately in extension to each other.

[0042] The joint construction is in Fig. 4 illustrated using the example of the pivot joint between the first mast arm segment 20 and the second mast arm segment 21. The pivot axis 74 is formed by a pivot pin 23, through which a proximal end of the mast arm segment 21 is connected to a distal end of the mast arm segment 20. Adjacent to the pivot pin 23, a first articulated lever 24 is attached to the first mast arm segment 20. Adjacent to the pivot pin 23, a second articulated lever 25 is attached to the second mast arm segment 21, adjacent to the pivot pin 23. The two articulated levers are articulated to one another at 26. A hydraulic cylinder 27 extends from a receptacle 28 on the first boom arm segment 20 to the outer end of the first articulated lever 24. Via the articulated levers 24, 25, a lifting movement of the hydraulic cylinder 27 is translated into a pivoting movement between the boom arm segments 20, 21.

[0043] One in Fig. 3 The boom arm segment 30 shown according to the invention extends from a proximal end 31 to a distal end 32. The boom arm segment 30 is designed as a box-shaped profile with an upper chord 33, a lower chord 34, and two side parts 35, 36. The box-shaped profile of the boom arm segment tapers continuously from the proximal end 31 to the receptacle 28 for the hydraulic cylinder. The two side parts 35, 36, as well as the upper chord 33 and the lower chord 34, thus approach each other with increasing distance from the proximal end 31.

[0044] Near the proximal end 31, the mast arm segment 30 is reinforced with a first reinforcement part 40, which forms a proximal joint receptacle 57 of the mast arm segment 30. Starting from the first reinforcement part 40, the box-shaped profile extends toward the distal end 32. The box-shaped profile is composed of an upper half-shell 41 and a lower half-shell 47, each formed as folded metal sheets.

[0045] According to the cross-sectional view in Fig. 12 The two side parts 35, 36 each comprise an upper edge section 42, which adjoins the upper chord 33, and a lower edge section 43, which adjoins the lower chord 34. The upper edge sections 42 and the lower edge sections 43 lie in the same plane. A central section 44 is arranged between the edge sections 42, 43, which has a lateral offset 56 relative to the edge sections 42, 43. The side parts 35, 36 are folded inwards so that the central sections 44 of the two side parts 35, 36 are spaced closer together than the edge sections 42, 43 of the side parts 35, 36. Between the central section 44 and the edge sections 42, 43, transition sections 45, 46 are formed, each of which encloses an angle of approximately 30° with the plane of the edge sections 42, 43 or the plane of the central sections 44 parallel thereto.

[0046] The upper half-shell 41 comprises the upper chord, the upper edge sections 42, the upper transition sections 45 and the upper part of the central sections 44 of both side parts 35, 36. The lower half-shell 47 comprises the lower chord 34, the lower edge sections 43, the lower transition sections 46 and the lower part of the central sections 44 of both side parts 35, 36. The upper end of the lower half-shell 47 overlaps with the lower end of the upper half-shell 41. At the lower end of the upper half-shell 47, a weld seam is formed which connects the two half-shells 41, 47 to one another. The lower half-shell 47 is folded inwards with its end edge 55 and thus forms a buckling stiffener for the box profile.

[0047] The first reinforcement part 40 has a greater material thickness than the box profile made of the half shells 41, 47, see Fig. 12 The outer side of the first reinforcement part 40 coincides with the outer side of the upper edge sections 42. The inner side of the first reinforcement part 40 coincides with the outer side of the central sections 44. The transition sections 45, 46 alternate the box profile between the outer and inner sides of the first reinforcement part 40.

[0048] The transition sections 45, 46 and the edge sections 42, 43 are welded butt-jointed to the first reinforcement part 40. The central sections 44 overlap with the first reinforcement part 40. The connection between the first reinforcement part 40 and the central sections 44 is formed by a circumferential weld seam around the first reinforcement part 40.

[0049] According to Fig. 5 , 10A joint bore 37 is formed in the first reinforcement part 40. The joint bore accommodates the joint pin 23, which connects the boom arm segment 30 to an adjacent boom arm segment. The joint lever 25 can be connected next to the joint bore 37. Accordingly, the boom arm segment 30 includes another joint bore 37 near its distal end, as well as another stud bolt 38, to which an articulated lever 24 can be connected.

[0050] The boom arm segment 30 includes an additional reinforcement part 50, which forms the mount 28 for the hydraulic cylinder. The additional reinforcement part 50 has the same material thickness as the first reinforcement part 40 and fits into the contour of the upper half-shell 41 in the same way. The additional reinforcement part 50 thus overlaps the central sections 44 of the side parts 35, 36 and is connected there to the upper half-shell 41 by a circumferential weld seam. The upper transition section 45 and the upper edge section 42 are butt-welded to the additional reinforcement part 50.

[0051] The Fig. 7 and 11The distal joint receptacle 51 shown comprises a reinforcement plate 52 that is doubled over the sheet metal of the box profile. The connection between the reinforcement plate 52 and the box profile is formed by a circumferential weld seam that extends over the circumference of the reinforcement plate 52. The joint receptacle 51 comprises a joint bore 37 that accommodates the joint pin 23 for connection to an adjacent mast arm segment. A stud bolt 38 is arranged next to the joint bore 37, to which the joint lever 25 is connected.

[0052] The boom arm segment includes Fig. 3 a plurality of mounting receptacles 53 for attaching holders (not shown) for the conveyor line 17. A first mounting receptacle 53 is connected to the first reinforcement part 40. Two further mounting receptacles 53 are arranged in the side parts 35, 36 of the box profile. A fourth mounting receptacle 53 is arranged near the distal joint receptacle 51.

[0053] According to the Fig. 8 und 9 The fastening receptacle 53 forms a cross connection 54 between the first side part 35 and the second side part 36. The cross connection 54 is formed by a pipe section that is welded to the central sections 44 of both side parts 35, 36. By keeping the side parts 35, 36 at a fixed distance from one another by the pipe section 54, the fastening receptacles 53 counteract buckling of the mast arm segment 30.

[0054] On the side of the first side part 35, the pipe section 54 ends as a pipe stub that protrudes slightly from the central section 44 of the side part 35. On the side of the second side part 36, the mounting receptacle 53 is provided with four threaded holes to which the holder for the conveyor line can be screwed.

[0055] According to Fig. 13The lower chord 34 is formed by a sheet metal that is flat in the longitudinal direction and has an outwardly curved shape in the transverse direction due to four folds 60. The proximal end 61 of the lower chord is formed by two laterally extending tips with a rounded recess in between. The side edges of the lower chord 34 are welded to the reinforcing parts 40, 70 up to the tips. The proximal end 61 of the lower chord lies in the center of the reinforcing parts 40, 70 and is thus spaced from the edge 75 of the reinforcing parts 40, 70, which lies in the extension of the lower chord 34.

[0056] The joint bore 37 extends within a pipe section that forms the joint connection 62. The pipe section is arranged with its entire cross-section below the plane 63 of the lower chord 34, so that no direct connection between the lower chord 34 and the joint connection 62 is possible.

[0057] Extending between the articulated connection 62 and the lower chord 34 is a transition piece 64, which is connected 65 to the lower chord 34 and 66 to the articulated connection 62. The connection 66 to the articulated connection 62 is spaced further apart from the plane 63 of the lower chord than the pivot axis 74. The transition piece 64 forms an angle 67 of approximately 20° with the plane 63 of the lower chord. This angle 67 is slightly larger than the angle 68 formed by the lower edge 69 of the reinforcement part 40 and the plane 63 of the lower chord. Relative to a given longitudinal position in the plane 63 of the lower chord 34, the distance 72 between the lower edge 69 of the reinforcement part 40 and the plane 63 is greater than the distance 71 between the transition piece 64 and the plane 63. The distance 76 between the connection 66 to the joint connection 62 and the plane 63 is greater than the distance 77 between the pivot axis 74 and the plane 63.

Claims

1. Boom arm segment for a concrete pump, having an upper belt (33), a lower belt (34) and two side portions (35, 36) which connect the upper belt (33) and the lower belt (34), wherein the boom arm segment (30) comprises an articulated joint (62) which defines a pivot axis (74) for a pivot connection between the boom arm segment (21) and an adjacent structure (20), wherein the pivot axis (74) is arranged below the plane (63) of the lower belt (34), wherein a transition piece (64) is arranged between the lower belt (34) and the articulated joint (62), wherein a first connection (65) is formed between the transition piece (64) and the lower belt (34), wherein the first connection (65) is spaced apart from the adjacent end (61) of the lower belt (34), wherein the transition piece (64) is enclosed between a first reinforcement portion (40) and a second reinforcement portion (70) which laterally adjoin the transition piece (64), characterized in that the reinforcement portions (40, 70) each have a lower edge (69) which extends from the articulated joint (62) to the lower belt (34) and wherein the lower edges (69) enclose an angle (68) with the plane (63) of the lower belt (34) which is smaller than the angle (67) which the transition piece (64) encloses with the plane (63) of the lower belt (34).

2. Boom arm segment according to Claim 1, characterized in that the lower belt (34) is provided with folded portions (60).

3. Boom arm segment according to Claim 2, characterized in that the lower belt (34) is curved in a transverse direction.

4. Boom arm segment according to one of Claims 1 to 3, characterized in that the transition piece (64) encloses an angle of between 5° and 50°, preferably between 10° and 40° with the plane (63) of the lower belt (34).

5. Boom arm segment according to one of Claims 1 to 4, characterized in that the transition piece (64) extends over the entire width of the lower belt (34).

6. Boom arm segment according to one of Claims 1 to 5, characterized in that the transition piece (64) is welded to the lower belt (34) and / or to the articulated joint (62).

7. Boom arm segment according to one of Claims 1 to 6, characterized in that a second connection (66) is formed between the transition piece (64) and the articulated joint (62) and in that the second connection (66) has a spacing (76) with respect to the plane (63) of the lower belt (34) which is larger than the spacing (77) between the pivot axis (74) and the plane (63) of the lower belt (34).

8. Boom arm segment according to one of Claims 1 to 7, characterized in that, with respect to a given longitudinal position of the lower belt (34), the spacing (72) between the lower edge (69) of the reinforcement portion (40, 70) and the plane (63) of the lower belt (34) is greater than the spacing (71) between the transition piece (64) and the plane (63) of the lower belt (34).

9. Boom arm segment according to one of Claims 1 to 8, characterized in that the end (61) of the lower belt (34) is enclosed between the reinforcement portions (40, 70) and in that the end (61) of the lower belt (34) is spaced apart from an edge (75), which is located in extension of the lower belt (34), of the reinforcement portion (40, 70).

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