CN114000894A

CN114000894A - Assembling trolley for assembling large-tonnage prefabricated structural blocks

Info

Publication number: CN114000894A
Application number: CN202111461405.1A
Authority: CN
Inventors: 刘在政; 张海涛; 邹海炎; 龚加文; 李太荣; 王庆楠; 卯春秋
Original assignee: China Railway Construction Heavy Industry Group Co Ltd
Current assignee: China Railway Construction Heavy Industry Group Co Ltd
Priority date: 2021-12-02
Filing date: 2021-12-02
Publication date: 2022-02-01

Abstract

The application discloses an assembling trolley for assembling large-tonnage prefabricated structural blocks, which comprises a trolley main body, a slewing bearing, an arm support and a gripper, wherein the slewing bearing is arranged on the trolley main body, two ends of the arm support are respectively hinged with the slewing bearing and the gripper, and the gripper pitching cylinder and the arm support pitching cylinder are correspondingly arranged at the hinged position; the gripper comprises a swing mechanism, a first translation mechanism, a second translation mechanism and a clamping mechanism which are connected in sequence, and the moving directions of the two translation mechanisms are mutually vertical; clamping mechanism includes the roof-rack and sets up top mould coupling assembling and side form coupling assembling on the roof-rack, and top mould coupling assembling is including the clamp arm that is used for the first top mould frock of centre gripping, and side form coupling assembling is including being used for with the axle type spare of the last U type groove joint of side form frock and being used for making lateral wall prefabricated structure piece keep vertical locating part when the joint. The structure has the installation freedom degree of a plurality of angles, meets the positioning requirement of a large-tonnage prefabricated member, and is safer and more efficient in operation.

Description

Assembling trolley for assembling large-tonnage prefabricated structural blocks

Technical Field

The invention relates to the technical field of tunnel supporting construction, in particular to an assembling trolley for assembling large-tonnage prefabricated structural blocks.

Background

In the tunnel construction process, need set up supporting construction at side and top, prevent the incident such as collapse, rock drop. The traditional supporting structure adopts a sprayed concrete manufacturing process, but in recent years, the process of assembling prefabricated structural blocks to replace concrete into a permanent support is rapidly developing and widely applied.

At present, no special supporting equipment is provided in China to implement the new process, and the prefabricated structural blocks are generally positioned and assembled by hoisting with a crane. But limited by the space in the tunnel, the flexibility of the suspension arm is poor when in use, a large amount of manpower is consumed for assistance in the installation process, and the single prefabricated structure block is large in weight and size and dangerous in hoisting operation, so that the installation speed is slow and the operation efficiency is influenced in order to reduce collision and shaking. In addition, the hoisting trolley generally needs to finish walking by means of a rail, the moving flexibility is poor, and the flatness of the ground in the tunnel can not be guaranteed based on actual construction conditions, so that the higher track laying requirement is difficult to meet, the condition that the crane is uneven is caused, and the hoisting operation on the prefabricated structural blocks is further influenced.

In conclusion, the existing process has the defects of high working strength, limited working range, poor flexibility, high assembling difficulty of the prefabricated structural blocks, dangerous operation and the like, and the prefabricated structural blocks positioned at the tunnel arch top cannot be installed. Therefore, a new device for assembling large-tonnage prefabricated structural blocks in the tunnel is urgently needed to be designed so as to meet the requirement of the existing tunnel supporting construction.

Disclosure of Invention

An object of this application is to provide an assemble platform truck for assembling large-tonnage precast structure piece, carry out the precast structure piece in the tunnel and assemble the formation and strut the work progress have remove nimble, hoist and mount convenient firm, assemble the high advantage of precision.

The technical scheme of the application is as follows:

an assembling trolley for assembling large-tonnage prefabricated structural blocks comprises a trolley main body and a mechanical arm, wherein the mechanical arm comprises a slewing bearing, an arm support and a gripper, the slewing bearing is arranged on the trolley main body, one end of the arm support is hinged with the slewing bearing, an arm support pitching oil cylinder for controlling arm support pitching action is arranged at the hinged position, the other end of the arm support is hinged with a supporting seat of the gripper, and the gripper pitching oil cylinder for controlling gripper pitching action is arranged at the hinged position;

the gripper is matched with a tool preassembled on the prefabricated structure block for use, the tool comprises a first top die tool installed on the top prefabricated structure block and a side die tool installed on the side wall prefabricated structure block, a clamping position is arranged on the first top die tool, and a U-shaped groove with a downward opening is arranged on the side die tool; the gripper further comprises a swing mechanism, a first translation mechanism, a second translation mechanism and a clamping mechanism, wherein the first translation mechanism is connected with a power output part of the swing mechanism, the second translation mechanism is connected with the power output part of the first translation mechanism, and the moving directions of the two translation mechanisms are perpendicular to each other;

the clamping mechanism comprises a top frame, a top die connecting assembly and a side die connecting assembly, wherein the top die connecting assembly and the side die connecting assembly are arranged on the top frame; the top frame is connected with the power output part of the second translation mechanism, the top die connecting assembly comprises at least one group of clamping arms connected with the clamping positions on the first top die tool and clamping oil cylinders used for providing power for the corresponding clamping arms, and the side die connecting assembly comprises shaft-shaped pieces used for being connected with U-shaped grooves in the side die tool in a clamped mode.

In some specific embodiments, the slewing mechanism includes a slewing reducer and a slewing pedestal, the first translation mechanism includes a first translation cylinder, a first slide rail and a sliding frame, the second translation mechanism includes a second translation cylinder, a second slide rail and a connecting frame, the first translation cylinder and the first slide rail are both fixedly disposed on the slewing pedestal, the sliding frame is slidably disposed on the first slide rail and connected to the power output end of the first translation cylinder, the second translation cylinder and the second slide rail are both fixedly disposed on the sliding frame, and the connecting frame is slidably disposed on the second slide rail and connected to the power output end of the second translation cylinder.

In some specific embodiments, the top frame is connected with the connecting frame through a rotating shaft, the gripper further comprises a swing oil cylinder, and two ends of the swing oil cylinder are respectively connected with the top frame and the connecting frame.

In some specific embodiments, the side die connecting assembly further includes a limiting member, the limiting member extends towards the side wall prefabricated structure block, and the extending length of the limiting member is set to be such that when the axial member is clamped with the U-shaped groove on the side die assembly, the side wall prefabricated structure block contacts with the limiting member and keeps a vertical state under the action of the limiting member.

In some specific embodiments, the number of the shaft-shaped parts is multiple and the shaft-shaped parts are arranged in the depth direction of the U-shaped groove.

In some specific embodiments, a second top die tool is further installed on the top prefabricated structure block, the second top die tool is of a cylindrical structure and is far away from one end opening of the top prefabricated structure block, and the top die connecting assembly further comprises a positioning piece which is used for being inserted into the second top die tool from the opening end and clamped.

In some specific embodiments, the lifting device further comprises an arm support follow-up oil cylinder, one end of the arm support follow-up oil cylinder is connected with the slewing bearing, the other end of the arm support follow-up oil cylinder is connected with the bottom surface of the arm support, and the arm support follow-up oil cylinder and the gripper pitching oil cylinder are controlled in a linkage mode and are opposite in stretching direction.

In some specific embodiments, the trolley main body comprises a trolley chassis, and a traveling system, a power control system and pressure-bearing support legs which are arranged on the trolley chassis, wherein the traveling system is of a wheel type structure, the power control system is used for providing power for traveling and working of an assembly trolley, the pressure-bearing support legs are arranged on two sides of the trolley chassis in a plurality of numbers and are symmetrically arranged, and hydraulic oil cylinders are arranged inside the pressure-bearing support legs and are used for achieving stretching of the pressure-bearing support legs in the vertical direction.

In some specific embodiments, the slewing bearing is arranged at one end of the chassis of the trolley, the other end of the chassis of the trolley is provided with a balancing weight, and an arm support frame is arranged on the balancing weight and used for placing the arm support in a non-working state during travelling.

In some specific embodiments, the pressure-bearing support leg is movably connected with the trolley chassis and used for realizing the transverse and/or longitudinal extension and contraction of the pressure-bearing support leg in the horizontal direction.

The technical scheme provided by the application has at least the following beneficial effects:

according to the technical scheme, the prefabricated part is grabbed to the preset installation position by the aid of the telescopic and pitching functions of the arm support and the hand grab, then different oil cylinders and rotary speed reducers on the hand grab are controlled, the posture of the prefabricated part is further adjusted, finally, a worker moves to the working position to install and fix the prefabricated part, hydraulic driving is adopted in the whole process, stability and operability are better, the hand grab and the mechanical arm have installation freedom degrees of multiple angles, accurate positioning requirements of the prefabricated part can be met, the installation range is wider, the operation process is safer and more efficient, and the strength and the danger of manual operation can be greatly reduced.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that other drawings may be derived from those drawings without inventive effort for a person skilled in the art.

Fig. 1 is a perspective view of an assembly trolley for assembling large-tonnage precast structural blocks according to an embodiment of the present disclosure;

FIG. 2 is a front view of FIG. 1;

FIG. 3 is a perspective view of the gripper of FIG. 2;

FIG. 4 is a front view of FIG. 3 (assembling the top prefabricated building block);

FIG. 5 is a rear view of FIG. 3;

FIG. 6 is a left side view of FIG. 3;

FIG. 7 is a right side view of FIG. 3 (assembling the side wall preform structural block);

FIG. 8 is a top view of FIG. 7;

FIG. 9 is a block diagram of a first top die tooling and a second top die tooling;

FIG. 10 is a block diagram of a side mold tooling;

in the figure: 01. the device comprises a first top die tool, a clamping position 01.1, a second top die tool, a side die tool 03, a side die tool 03.1 and a U-shaped groove; 1. the device comprises a supporting seat, 2, a rotary speed reducer, 3, a rotary seat, 4, a first translation oil cylinder, 5, a first sliding rail, 6, a sliding frame, 7, a second translation oil cylinder, 8, a second sliding rail, 9, a connecting frame, 10, a rotating shaft, 11, a top frame, 12, a swing oil cylinder, 13, a clamping arm, 14, a clamping oil cylinder, 15, a positioning piece, 16, a shaft type piece, 17, a limiting piece, 18, an arm frame, 19, a rotary support, 20, an arm frame pitching oil cylinder, 21, a hand grip pitching oil cylinder, 22, an arm frame following oil cylinder, 23, a trolley chassis, 24, a walking system, 25, a power control system, 26, a pressure-bearing supporting leg, 27, a balancing weight, 28 and an arm frame supporting frame.

Detailed Description

In order to facilitate understanding of the present application, the technical solutions in the present application will be described more fully and in detail with reference to the drawings and the preferred embodiments, but the scope of protection of the present application is not limited to the following specific embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

It will be understood that when an element is referred to as being "coupled" or "connected" to another element, it can be directly coupled, connected or communicated with the other element or indirectly coupled, connected or communicated with the other element via other intervening elements.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present application.

Examples

Referring to fig. 1 to 10, an assembly trolley for assembling large-tonnage prefabricated structural blocks includes a trolley main body and a robot arm.

The trolley main body comprises a trolley chassis 23, and a traveling system 24, a power control system 25 and pressure-bearing support legs 26 which are arranged on the trolley chassis 23. The traveling system 24 adopts a wheel type structure, so that the trolley can conveniently and rapidly move in two directions; the power control system 25 is used for providing power for the walking and the working of the trolley and controlling the use of the whole trolley; in this embodiment, the number of the pressure-bearing support legs 26 is four and is divided into two groups, the two groups are symmetrically arranged at the front end and the rear end of the trolley chassis 23, hydraulic oil cylinders are arranged in the pressure-bearing support legs 26 and used for achieving the stretching of the pressure-bearing support legs in the vertical direction, the pressure-bearing support legs 26 are movably connected with the trolley chassis 23, the pressure-bearing support legs can be close to or far away from the trolley chassis 23 in the horizontal direction along the transverse direction (longitudinal direction), and stable support with a large enough area is provided for the trolley to work.

The mechanical arm comprises a slewing bearing 19, an arm support 18 and a gripper, wherein the slewing bearing 19 is arranged at the front end of a trolley chassis 23, the rotation of the arm support 18 in the horizontal direction is controlled through hydraulic drive, one end of the arm support 18 is hinged to the slewing bearing 19, the arm support 18 is divided into three sections along the length direction, two-stage stretching is achieved through an internally arranged hydraulic oil cylinder so as to meet the installation requirements of different heights, an arm support pitching oil cylinder 20 is arranged at the hinged position of the arm support 18 and the slewing bearing 19, one end of the arm support pitching oil cylinder 20 is connected with the slewing bearing 19, the other end of the arm support is connected with the side face of the arm support 18, the pitching action of the arm support is controlled through hydraulic drive, the other end of the arm support 18 is hinged to a support seat 1 of the gripper, the gripper pitching oil cylinder 21 is arranged at the hinged position, and the pitching action of the gripper is controlled through the gripper pitching oil cylinder 21.

In the embodiment, an arm support follow-up oil cylinder 22 is further arranged in cooperation with the gripper pitching oil cylinder 21, one end of the arm support follow-up oil cylinder 22 is connected with the slewing bearing 19, and the other end of the arm support follow-up oil cylinder is connected with the bottom surface of the arm support 18, so that the arm support follow-up oil cylinder can move along with the pitching of the arm support. The arm support follow-up oil cylinder 22 and the gripper pitching oil cylinder 21 are in linkage control, the stretching directions of the two oil cylinders are opposite, namely when the arm support 18 follow-up oil cylinder 7 extends out, the gripper pitching oil cylinder 21 retracts, and therefore the whole gripper can be guaranteed to be always horizontal.

In order to ensure the stability of the trolley during working, a counterweight 27 is also arranged at the tail part of the trolley chassis 23; the boom support frame 28 is arranged on the counterweight block 27, when the boom 18 works, the boom 18 retracts and rotates to move above the boom support frame 28, the boom 18 descends to be fixedly connected with the boom support frame 28, and therefore the trolley can conveniently drive and the stability of the driving is guaranteed.

The tongs uses with the frock cooperation of pre-installation on prefabricated structure piece, the frock is including installing first top mould frock 01, second top mould frock 02 on the prefabricated structure piece in top and installing the side form frock 03 on the prefabricated structure piece of lateral wall, be equipped with clamping position 01.1 on the first top mould frock 01, second top mould frock 02 is cylindric structure and keeps away from the one end opening of the prefabricated structure piece in top, be equipped with U type groove 03.1 that the opening is down on the side form frock 03, U type groove 03.1's quantity can be designed according to actual conditions.

The gripper comprises a supporting seat 1, a swing mechanism, a first translation mechanism, a second translation mechanism and a clamping mechanism, wherein the first translation mechanism is connected with a power output part of the swing mechanism, the second translation mechanism is connected with the power output part of the first translation mechanism, and the moving directions of the two translation mechanisms are perpendicular to each other.

The clamping mechanism comprises a top frame 11, a top die connecting assembly and a side die connecting assembly, wherein the top die connecting assembly and the side die connecting assembly are arranged on the top frame; the top frame 11 is connected with the power take off part of second translation mechanism, side form coupling assembling including be used for with the side form frock on the axle type 16 of U type groove joint, top form coupling assembling include two be used for with first top form frock on the clamping arm 13 that the centre gripping position is connected and be used for corresponding the clamping cylinder 14 that presss from both sides the arm and provide power, top form coupling assembling still includes the setting element 15 that is used for inserting second top form frock in and the joint from the open end, setting element 15 sets up between two clamping arm 13. Considering that when the prefabricated structure blocks at the top are assembled, the clamping arms 13 play a role in fixing and supporting, in order to prolong the service life of equipment and enhance the operation safety, the pressure applied to the clamping arms 13 can be dispersed in a manner of increasing stress points, namely, the matched positioning piece 15 and the second top die tooling 02 are arranged to support the prefabricated structure blocks at the top, and the number of the positioning pieces can be increased or decreased according to the actual situation.

The slewing mechanism comprises a slewing reducer 2 and a slewing seat 3, the first translation mechanism comprises a first translation oil cylinder 4, a first slide rail 5 and a sliding frame 6, and the second translation mechanism comprises a second translation oil cylinder 7, a second slide rail 8 and a connecting frame 9.

One end of the rotary speed reducer 2 is connected with the supporting seat 1, the other end of the rotary speed reducer is connected with the rotary seat 3, and the rotation of the top frame 11 in the circumferential direction can be realized through hydraulic driving. The first translation oil cylinder 4 and the first slide rail 5 are both fixedly arranged on the rotary base 3, the sliding frame 6 is slidably arranged on the first slide rail 5 and is connected with the power output end of the first translation oil cylinder 4, the second translation oil cylinder 7 and the second slide rail 8 are both fixedly arranged on the sliding frame 6, and the connecting frame 9 is slidably arranged on the second slide rail 8 and is connected with the power output end of the second translation oil cylinder 7.

The slide rail can be a finished rail or a pressing plate gap arrangement to form a rail, the latter is the embodiment. The sliding frame 6 is transversely limited by the first sliding rail 5, the connecting frame 9 is longitudinally limited by the second sliding rail 8, and the top frame 11 can move in the axial direction by driving the corresponding translation oil cylinder.

Roof-rack 11 places on link 9 and the two is connected through pivot 10 between the two, sets up swing hydro-cylinder 12, roof-rack 11 and link 9 are connected respectively to the both ends of swing hydro-cylinder 12, make roof-rack 11 can revolute pivot 10 and rotate through hydraulic drive swing hydro-cylinder 12, and then realize roof-rack 11 rotation in vertical side.

The side form coupling assembling still includes locating part 17, locating part 17 sets up and extends length to the prefabricated structure piece direction of lateral wall and sets up to when the U type groove 03.1 joint on axial component 16 and the side form frock, the prefabricated structure piece of lateral wall contacts with the locating part and keeps vertical state under its effect. When side form coupling assembling cooperation frock was carried out the operation promptly, locating part 17 can support tightly on lateral wall prefabricated structure piece, avoids the prefab to rotate around axial type spare 16, plays limiting displacement. In other specific embodiments, the number of the shaft-shaped members 16 may be multiple and the shaft-shaped members 16 may be arranged in the depth direction of the U-shaped groove, a straight line may be determined according to two points, and the shaft-shaped members 16 arranged in a straight line may perform a similar limiting function on the U-shaped groove, and also prevent the side wall prefabricated structural block from shaking.

In this embodiment, shaft type spare 16 is ox horn axle construction, can avoid the outside slip of U type groove to lead to prefabricated structure piece to drop, guarantees operation safety.

The assembly trolley provided by the embodiment can meet the assembly operation of 5 tons of prefabricated structural blocks and below.

The above description is only a few examples of the present application and does not limit the scope of the claims of the present application, and it will be apparent to those skilled in the art that various modifications and variations can be made in the present application. Any improvement or equivalent replacement directly or indirectly applicable to other related technical fields within the spirit and principle of the present application by using the contents of the specification and the drawings of the present application shall be included in the protection scope of the present application.

Claims

1. The assembling trolley for assembling the large-tonnage prefabricated structural blocks is characterized by comprising a trolley main body and a mechanical arm, wherein the mechanical arm comprises a slewing bearing (19), an arm support (18) and a gripper, the slewing bearing (19) is arranged on the trolley main body, one end of the arm support (18) is hinged with the slewing bearing (19), an arm support pitching cylinder (20) used for controlling the arm support to pitch is arranged at the hinged position, the other end of the arm support (18) is hinged with a support seat (1) of the gripper, and a gripper pitching cylinder (21) used for controlling the gripper to pitch is arranged at the hinged position;

the gripper is matched with a tool preassembled on the prefabricated structure block for use, the tool comprises a first top die tool (01) installed on the prefabricated structure block at the top and a side die tool (03) installed on the prefabricated structure block at the side wall, a clamping position (01.1) is arranged on the first top die tool, and a U-shaped groove (03.1) with a downward opening is arranged on the side die tool; the gripper further comprises a swing mechanism, a first translation mechanism, a second translation mechanism and a clamping mechanism, wherein the first translation mechanism is connected with a power output part of the swing mechanism, the second translation mechanism is connected with the power output part of the first translation mechanism, and the moving directions of the two translation mechanisms are perpendicular to each other;

the clamping mechanism comprises a top frame (11), and a top die connecting assembly and a side die connecting assembly which are arranged on the top frame; the top frame (11) is connected with the power output part of the second translation mechanism, the top die connecting assembly comprises at least one group of clamping arms (13) which are used for being connected with the clamping positions on the first top die tool and clamping oil cylinders (14) which are used for providing power for the corresponding clamping arms, and the side die connecting assembly comprises shaft-shaped pieces (16) which are used for being connected with U-shaped grooves on the side die tool in a clamped mode.

2. Assembly trolley for assembling large-tonnage precast structural blocks according to claim 1, the slewing mechanism comprises a slewing reducer (2) and a slewing seat (3), the first translation mechanism comprises a first translation oil cylinder (4), a first slide rail (5) and a sliding frame (6), the second translation mechanism comprises a second translation oil cylinder (7), a second slide rail (8) and a connecting frame (9), the first translation oil cylinder (4) and the first slide rail (5) are both fixedly arranged on the rotary seat (3), the sliding frame (6) is arranged on the first sliding rail (5) in a sliding way and is connected with the power output end of the first translation oil cylinder (4), the second translation oil cylinder (7) and the second slide rail (8) are both fixedly arranged on the sliding frame (6), the connecting frame (9) is arranged on the second sliding rail (8) in a sliding mode and is connected with the power output end of the second translation oil cylinder (7).

3. The assembly trolley for assembling large-tonnage precast structural blocks according to claim 2, wherein the top frame (11) is connected with the connecting frame (9) through a rotating shaft (10), the gripper further comprises a swing oil cylinder (12), and two ends of the swing oil cylinder (12) are respectively connected with the top frame (11) and the connecting frame (9).

4. The assembling trolley for assembling large-tonnage prefabricated structure blocks according to claim 2, wherein the side-die connecting assembly further comprises a limiting member (17), the limiting member (17) extends towards the side-wall prefabricated structure block and the length of the extending length is set to be that when the side-wall prefabricated structure block (16) is clamped with a U-shaped groove on the side-die tooling, the side-wall prefabricated structure block is in contact with the limiting member and keeps a vertical state under the action of the limiting member.

5. Assembly trolley for assembling large-tonnage precast structural blocks according to claim 2, characterized in that the number of the axle-shaped pieces (16) is multiple and arranged in line along the depth direction of the U-shaped groove.

6. The assembling trolley for assembling large-tonnage prefabricated structure blocks according to claim 2, wherein a second top die tooling (02) is further installed on the top prefabricated structure block, the second top die tooling is of a cylindrical structure and is far away from an opening at one end of the top prefabricated structure block, and the top die connecting assembly further comprises a positioning piece (15) which is inserted into the second top die tooling from the opening end and is clamped.

7. The assembly trolley for assembling the large-tonnage precast structural block according to claim 2, further comprising an arm support follow-up cylinder (22), wherein one end of the arm support follow-up cylinder (22) is connected with the slewing bearing (19) and the other end is connected with the bottom surface of the arm support (18), and the arm support follow-up cylinder (22) and the gripper pitching cylinder (21) are controlled in a linkage manner and have opposite extension directions.

8. The assembling trolley for assembling large-tonnage precast structural blocks according to any one of claims 2 to 7, wherein the trolley main body comprises a trolley chassis (23), and a traveling system (24), a power control system (25) and pressure-bearing support legs (26) which are arranged on the trolley chassis (23), the traveling system (24) is of a wheel type structure, the power control system (25) is used for providing power for traveling and working of the assembling trolley, the pressure-bearing support legs (26) are multiple and are symmetrically arranged on two sides of the trolley chassis (23), and hydraulic oil cylinders are arranged inside the pressure-bearing support legs (26) and are used for achieving stretching of the pressure-bearing support legs in the vertical direction.

9. Assembly trolley for assembling large tonnage precast structural blocks according to claim 8 characterized by that the slewing bearing (19) is placed at one end of the trolley chassis (23) and at the other end a counterweight (27), on which counterweight (27) a boom support (28) is placed for placing the boom in non-working condition during driving.

10. Assembly trolley according to claim 9 for assembling large tonnage precast structural blocks, characterized in that the pressure bearing legs (26) are movably connected to the trolley chassis (23) for horizontal and/or longitudinal extension of the pressure bearing legs.