GB2125004A

GB2125004A - Telescopic boom with means for supporting and/or guiding its constitutive sections

Info

Publication number: GB2125004A
Application number: GB08321052A
Authority: GB
Inventors: Pierre Auguste Pellier
Original assignee: PPM SA; Potain Poclain Materiel PPM SA
Current assignee: PPM SA; Potain Poclain Materiel PPM SA
Priority date: 1982-08-10
Filing date: 1983-08-04
Publication date: 1984-02-29
Also published as: DE3326108A1; JPS5948388A; GB8321052D0; DE3326108C2; FR2531691B1; FR2531691A1; GB2125004B

Abstract

A telescopic boom with two sliding sections 1,2, comprises one supporting and/or guiding assembly 3 with at least two members, shown as wheels 4, supported by one, 3, of the two sections, whereas a plane face 5, provided on the second section, is in resting contact on the members 4. Each member 4 is associated to a jack with two elements 11, 12 movable one with respect to the other, the first, 11, of said two elements being fixed on one section, whereas the second, 12, supports the member 4 and each jack comprises a chamber 20 adapted to contain a substantially incompressible fluid and to communicate with the chambers 20 of the other jacks of the said supporting and/or guiding assembly. <IMAGE>

Description

SPECIFICATION Telescopic boom with means for supporting and/or guiding its constitutive sections The present invention relates to a device which has been developed to meet the requirement of "telescoping under load" for telescopic booms of increasingly powerful machines.

The load limit of current systems is reached for a number of reasons: -the necessity to evenly distribute the load over all the runner wheels, this by assembly on balance beams, -limit equal to two out of the number of runner wheels, per balance beam, -application of the load on a small number of points (equal of course to the number of runner wheels), cxaggerated dimensions of the runner wheels supporting strains of 20 to 25 tons, --difficulty, if not impossibility, to finely adjust the possible counter-booms of the sections one with respect to the other.

It is the object of the present invention to overcome the present drawbacks in the design of telescopic booms by proposing one such telescopic boom with at least two sliding sections, comprising at least one supporting and/or guiding assembly with at least two members, supported by one of the two section, whereas a plane face, provided on the second section, is in resting contact on the said members.

Each member is associated to a jack with two elements movable one with respect to the other, the first of said two elements being fixed on the first section, whereas the second supports the said member and each jack comprises a chamber adapted to contain a substantially incompressible fluid and to communicate with the chambers of the other jacks of the said supporting and/or guiding assembly.

The following advantageous dispositions are also preferably adopted: -the first respective elements of the jacks in each supporting and/or guiding assembly are made in one piece; -said piece is removably secured on the first section; -the jack chambers in each assembly are connected in parallel to a source of pressurized fluid via an "instant connection" fitting;; -the said members being also constituted by runner wheels, each jack is of the linear type with a piston rod supporting the corresponding runner wheel, and being defined by a plane face situated opposite and contiguously to a plane face in a structure integral with the first section, so that said piston has a substantially constant orientation about its axis this keeping an equally substantially constant orientation of said runner wheel with respect to the plane face of the second section on which it rests.

The invention will be more readily understood on reading the following description with reference to the accompanying drawings, in which: Figure 1 is a simplified axial section of a telescopic boom according to the invention; Figure 2 is a simplified cross-section of a supporting and/or guiding assembly according to the invention; Figure 3 is a cross-sectional view of a detail from the assembly shown in Fig. 2, according to another working configuration; Figure 4 is a cross-sectional view along line IV-IV of Fig. 6; Figure 5 is a perspective view of the recess housing the supporting and/or guiding assembly mounted at the front of the external section of the boom of Fig. 1; Figure 6 is a cross-section along lines VI-VI of Fig. 4 of the assembly mounted in the recess of Fig. 5;; Figure 7 is a perspective view of the recess for the supporting and/or guiding assembly mounted at the back of the internal section of the boom of Fig. 1; Figure 8 is a cross-section similar to that shown in Fig. 6, but showing the assembly mounted in the recess according to Fig. 7.

Referring first to Fig. 1, this shows the boom, comprising: -an external section 1, -an internal section 2, mounted in telescopic manner inside the internal section 1, a first assembly 3 of four runner wheels 4, mounted on the front end of the external section 1, the wheels 4 resting on the lower face 5a of the lower flat plate 5 which defines the internal section 2: -a second assembly 6 of four runner wheels, mounted on the rear end of the internal section 2, the wheels 7 resting on the lower face 8a of the upper flat plate 8 defining the external section 1, a handling hook 9 suspended to a lifting cable 10 which extends inside the boom, Each assembly 3/6 of runner wheels 4 is constituted by:: a monobloc support 7 in which four cylinders 11 are fitted in alignment, -four pistons 12, each one mounted for sliding in one of the cylinders 11, -the four runner wheels 4 which are fitted at the external ends of the pistons 12, one to each piston, by means of a two-shanked fork 13, between the shanks of which, the associated runner is placed, and of an axle 14 supporting the runner and being provided with a flat head 15, -a single longitudinal conduit 16, traversing the support 7 and being closed off at one end by a threaded plug 17, the other end being provided with a tapping 1 8 for the removable insertion of an "instant fitting" 19, -working chambers 20, defined by said cyl inders 11 and pistons 1 2 -short conduits 21, each one connecting a chamber 20 to the conduit 16, -a non-return valve 22, installed in the conduit 16 between the different conduits 21 and the tapping 1 8.

It is to be noted that, in the configuration wherein the fitting 1 9 is screwed into the tapping 18, the internal end 23 of said fitting opens the valve 22 (Fig. 2), whereas, when the fitting is not screwed in, the valve 22 is closed and isolates the different chambers from the outside of the support 7. Said fitting 19, is moreover connected to the delivery pipe 24 of a pump 25, which in the illustrated example, is hand-operated 26, and which pump is in turn connected via its induction pipe 27 to a reservoir of non-compressible fluid (hydraulic oil) 28.

Figs. 5 to 8 show particular ways of mounting assemblies 3 and 6 on sections 1 and 2 respectively.

The front part of section 1 comprises a lower plate 29 parallel to the upper plate 8 and two vertical spaced apart plates 30, said four plates which are welded together, giving to the illustrated section 1 a rectangular crosssection. Two assemblies 3 are provided close to the vertical walls 30. To this effect, a special box-like fitting recess is provided which recess is constituted by two vertical spaced-apart plates 31 and 32 welded to the same horizontal base-plate 33, plate 32 being in fact an extension of the adjacent vertical plate 30 of section 1. Two holes 36 are provided in plate 32 to receive screws 34 cooperating with tappings 35 made in the support 7 of assembly 3 to secure the said assembly on the section 1.It should be noted that said assembly 3 is fitted between the plates 31 and 32 by being horizontally slid therebetween, in the direction of arrow F parallel to the longitudinal axis Al of section 1.

The rear part of section 2 comprises an upper plate 37 which is parallel to the lower plate 5 and two vertical plates 38, all of said four plates being joined together by welding and giving to the section 2 a rectangular cross-section. Two indentation are made in the top corners of the rear part of the section 2, each one being defined by a longitudinal vertical plate 39, a vertical cross-plate 40 and a horizontal base-plate 41. Two holes 42 are provided in each longitudinal vertical plate 39 to receive two fastening screws 43 of an assembly 6, said screws cooperating with bores 35 provided in the support 7 of said assembly 6.

The advantages of the embodiments described hereinabove are as follows.

First of all, a ready fitting on sections 1, 2 of a telescopic boom, of assemblies 3, 6, is noted.

It is also noted that the pressures in the chambers 20 of a support 7 are equal since said chambers are connected in parallel via conduits 21 to the same conduit 16. As a result, the bearing forces transmitted to the different runners 4 are all equal without having to adopt balance beams.

It is also noted that according to the recommended disposition, which in the illustrated example is adapted to four-runner assemblies, is also suitable for assemblies 3 or 6 comprising any number of runners. Assemblies with four runners or more (five or six for example) or less (such as two or three) will work exactly in the same way as described hereinabove.

It is therefore possible to design telescopic booms comprising as many runners as needed to support the strain on the apparatus whilst in service.

Finally, it is possible by controlling the quantity of oil contained in chambers 20 to obtain better conditions of support and guidance of one section with respect to the other.

It is also to be noted that the assembly of each support 7 on the corresponding portion and its fastening on the vertical plate 32/39, places the head 1 5 of the axle supporting the runner 4 opposite and parallel to the inner face 32a/39a of the plate 32/39 with only a slight initial play L. According to this disposition, the head of said axle, and as a result the runner 4 itself, cannot, in service, rotate with respect to the section on which they are mounted, hence keeping a constant orientation with respect to the direction of telescoping.

The invention is in no way limited to the description given herein, but on the contrary covers any variants which can be brought thereto, without departing from its scope or its spirit.

In particular, what is found with runners as supporting members, would also be found with slide blocks, except of course for the friction characteristics.

Claims

1. A telescopic boom with at least two slideable elements, comprising at least one supporting and/or guiding assembly with at least two members, supported by one of the two sections, whereas a plane face, provided on the second section, is in resting contact on the said members, wherein each member is associated to a jack with two elements movable one with respect to the other, the first of said two elements being fixed on the first section, whereas the second supports the said member and each jack comprises a chamber adapted to contain a substantially incompressible fluid and to communicate with the chambers of the other jacks of the said supporting and/or guiding assembly.

2. A telescopic boom according to claim 1, wherein the first respective elements of the jacks in each supporting and/or guiding assembly are made in one piece.

3. A telescopic boom according to claim 2, wherein said piece is removably secured on the first section.

4. A telescopic boom according to claim 1, wherein the jack chambers in each assembly are connected in parallel to a source of pressurized fluid via an "instant connection" fitting.

5. A telescopic boom according to claim 1, wherein the said members being in known manner constituted by runner wheels, each jack is of the linear type with a piston rod supporting the corresponding runner wheel, and being defined by a plane face situated opposite and contiguously to a plane face in a structure integral with the first section, so that said piston has a substantially constant orientation about its axis thus keeping an equally substantially constant orientation of said runner wheel with respect to the plane face of the second section on which it rests.

6. A telescopic boom substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.