GB2076894A

GB2076894A - Telescopic jacks

Info

Publication number: GB2076894A
Application number: GB8108418A
Authority: GB
Original assignee: OFFICINE ROMANAZZI SpA
Current assignee: OFFICINE ROMANAZZI SpA
Priority date: 1980-03-20
Filing date: 1981-03-18
Publication date: 1981-12-09
Also published as: GB2076894B; IT8048217A0; FR2482215A1; DE3110425A1; IT1126990B; FR2482215B1

Abstract

A telescopic multi-section lifting jack in which the innermost and outermost sections 31, 37 (Figure 1) are connected to end parts co-operating with end pieces 47, 46 to provide ball and socket joints at either end of the jack. The lower of the two end parts (38) is of hollow hemispherical form and accepts the lower end portions of all but the outermost (fixed) section 31 when the jack is fully collapsed. In this condition, the upper end portions of the various sections present a stepped conical concavity which partly houses the upper end piece 46. <IMAGE>

Description

SPECIFICATION Telescopic multi-section lifting jacks The present invention relates to telescopic multisection lifting jacks. In particular, but not exclusively, the invention relates to hydraulic lifting jacks of the multi-section type for use with tipping bodies or other vehicle-mounted structures.

The object of the invention is to provide a telescopic multi-section lifting jack which, when collapsed, is relatively compact compared with conventional lifting jacks having the same maximum extension.

According to the present invention, a telescopic multi-section lifting jack comprises a cup-form endpiece co-operating with a spherical end-part of the jack to provide a ball and socket joint, said end-part being adapted to accommodate end portions of at least some of the sections when the jack is fully collapsed.

Conveniently, the end part is provided by or is secured to the jack section of maximum diameter which section provides an enclosure for the remaining sections when the jack is fully collapsed.

Conveniently, in this latter case, the end-part of the jack presents a tapering concavity to accommodate the end portions of said remaining sections whereby when the jack is fully collapsed, the upper edges of the sections describe a similarly tapering concavity accommodating a second end-piece of the jack.

Conveniently in this case, the second end-piece is also of cup-form and the jack-section of smallest diameter provides or is secured to a second spherical end-part which co-operates with said second end-piece to form a second ball and socket joint in the jack.

Conveniently, the or each tapering concavity is of generally hemi-spherical or conical form.

Conveniently, the jack sections carry guide bushings engaging adjacent sections of the jack to provide rigidity when the jack is in its fully or partially expanded state.

Conveniently, where the jack is adapted to be hydraulically operated, multi-part guide bushings positioned at one end of the sections adjacent oil-seal rings for these sections, are separated from said oil-seal rings by anti-extrusion rings adapted to prevent extrusion of the oil-seal rings into spaces between the different parts of the adjacent guide bushings.

Conveniently, the maximum displacement of each section relative to the neighbouring sections of the jack, is determined by stops fitted to the section and its neighbours.

According to another aspect of the invention, there is provided a telescopic multi-section lifting jack comprising, in combination, a central stem connected with an upper end piece, a base support of hollow hemi-spherical form which constitutes a lower end piece, and a co-axial series of cylindrical elements or sections interposed between the two end pieces and having upper edges which form a stepped conical surface contained beneath the said upper end piece, and lower edges adjacent and housed in the said hemispherical base surface.

Conveniently, the external cylindrical element or section is fixed directly to a spherical base which rests on said lower sperical end piece and is articulated relative to it.

Conveniently, near the upper extremes of the sections, each said seat contains a guide bushing which is divided into four pieces, said guide bushing having the task of ensuring the perfect running of the telescopic elements.

Conveniently the upper part of each said guide bushing contains a dust-scraper ring and an oil seal is mounted below each said guide bushing.

Conveniently an anti-extrusion ring is interposed between each annular oil seal and the adjacent guide bushing, the anti-extrusion ring having the function of isolating the seal from the junctions of the different parts forming the bushing.

Conveniently a series of guide rings each divided into two pieces is mounted near the lower edges of the sections and a pair of stop rings is mounted at positions corresponding to the extreme end-oftravel positions of each section.

The invention also includes a vehicle having a tipping body or other vehicle-mounted structure actuated by a jack according to the present invention. Such jacks are in fact particularly advantageous in this context because they permit the necessary lifting angles to be obtained (typically from 48" to 50 ) without the usual disadvantage of having the lower end of the jack project beneath the vehicle frame. This permits standardisation of the lifting equipment for these vehicles and allows a single piece of lifting equipment to be used in any make of vehicle lying within a certain range e.g. 3 to 5 tonnes.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings in which: Figure 1 shows the lifting jack fully collapsed, half in section, half in perspective; and Figure 2 shows a perspective view, to a reduced scale, of the jack when fully extended.

Thus referring first to Figure 1, dust-scraper sealing rings 1 to 6 made in nitrile rubber are used to protect the jack sections 31 to 37 from the ingress of harmful materials. The dust-scrapers are mounted in guide bushings 7 to 12 each of which is divided into four pieces to facilitate assembly within the hollows of the sections. The bushings are preferably made in acetal resins loaded with glass so as to be able to guide the jack sections without scratching them.

Oil seal rings 19 to 24 made in reinforced nitrile rubber are mounted beneath the guide bushings 7 to 12 from which they are separated by anti-extrusion rings 13to 18designedto prevent extrusion of the oil seals into the gaps between the different pieces of the four-piece bushings. Anti-extrusion rings 13 to 18 are each made, as a single piece, in acetal resin loaded with glass.

Spring steel snap-ring stops 25 - 30 fitted at the top ends of the sections co-operate with guide-ring stops 40 to 45 fitted at the bottom ends of the sections to block the various sections at the end of their upward travel. In the situation shown in Figure 1 on the other hand, the stops 40 to 45 are shown co-operating with snap-ring stops 26' to 30' fitted at the bottom ends of the sections to block the sections at the end of their downward travel. The stops 40 to 45 are made in spheroidal cast iron and each is in the form of the two half-rings to assist assembly.

When the jack is fully collapsed, the bottom section 31 serves as a container jacket forthe other co-axial sections 32 to 37. Section 31 is screwed into a spherical bottom 38 which provides a bottom end-part of the illustrated embodiment and this in turn is supported on the spherical seat of a bottom end-piece 47 to provide a ball-and-socket joint there.

An O-ring seal 39 is mounted at the bottom of the screw thread in section 31 just above the transfer port from pipe union 40 through which hydraulic oil passes into and out of the space embraced by the jack sections to expand or collapse the jack as the case may be.

The arrangement is completed by an upper spherical end-part mounted at the top of the innermost section or stem 37 and co-operating with the spherical seat of a top end-piece plate 46 to provide a second bail-and-socket joint in the jack.

As will be seen from Figure 1, when the jack is fully collapsed, the lower end portions of sections 32 to 37 are all accommodated within the spherical bottom 38 so as to give a relatively compact arrangement for a jack having the maximum extension configuration shown in Figure 2. This effect is enhanced by having the end-piece plate 46 largely contained within the downwardly4apering stepped conical space presented by the upper edges of sections 32 to 37 within the confines of outer section 31.

In operation of the jack, beginning from the positions shown in Figure 1, oil under pressure is fed into the interior of bottom 38 through the pipe union 48 and acting on the bottom end faces of sections 32 to 37 forces them upwards as a block inside bottom section 31. Sections 32 to 37 continue to move in this way until the stop ring 40 on section 32 abuts with stop ring 25 on sections 31. This prevents further upward movement of section 32 but the remaining sections continue to move upwardly until stop ring 41 on section 33 abuts with stop ring 26 on section 32 to hold section 33 back from further upward movement. The process is repeated for successive sections 34to 37 until the jack is in the fully-extended position shown in Figure 2.

To collapse the jack, oil is removed from bottom 38 through pipe union 48 and the sections move into each other by amounts determined by the abutment of stop rings 41,26' and 42,27' etc. until the final fully-collapsed position of Figure 1 is once again obtained.

The present invention has been described in one of its preferred embodiments but it is to be understood that different embodiments can be put into practice by an expert in the art without going outside the scope of the following claims.

Claims

1. Atelescopic multi-section lifting jack comprising a cup-form end-piece co-operating with a spher ical end-part of the jack to provide a ball and socket joint, said end part being adapted to accommodate end portions of at least some of the sections when the jack is fully collapsed.

2. A jack as claimed in Claim 1 in which the end part is provided by or is secured to the jack section of maximum diameter which section provides an enclosure for the remaining sections when the jack is fully collapsed.

3. A jack as claimed in Claim 2 in which the end part of the jack presents a tapering concavity to accommodate the end portions of said remaining sections whereby when the jack is fully collapsed the upper edges of the sections describe a similarly tapering concavity accommodating a second endpiece of the jack.

4. A jack as claimed in Claim 3 in which the second end-piece is also of cup-form and the jack-section of smallest diameter provides or is secured to a second spherical end-part which cooperates with said second end-piece to form a second ball and socket joint.

5. Ajack as claimed in any preceding claim in which the or each tapering concavity is of generally hemi-spherical or conical form.

6. A jack as claimed in any preceding claim in which the jack sections carry guide bushings engaging adjacent sections of the jack to provide rigidity when the jack is in its fully or partially expanded state.

7. A jack as claimed in any preceding claim where the jack is adapted to be hydraulically operated and is provided with multi-part guide bushings positioned at one end of the sections adjacent oil-seal rings for these sections, the guide sections being separated from said oil-seal rings by antiextrusion rings adapted to prevent extrusion of the oil-seal rings into spaces between the different parts of the adjacent guide bushings.

8. A jack as claimed in any preceding claim in which the maximum displacement of each section relative to the neighbouring sections of the jack is determined by stops fitted to the section and its neighbours.

9. Atelescopic multi-section lifting jack comprising, in combination, a central stem connected with an upper end piece, a base support of hollow hemi-spherical form which constitutes a lower end piece, and a co-axial series of cylindrical elements or sections interposed between the two end pieces and having upper edges which form a stepped conical surface contained beneath the said upper end piece, and lower eges adjacent and housed in the said hemispherical base surface.

10. A jack as claimed in Claim 9 in which the external cylindrical element or section is fixed directly to a spherical base which rests on said lower spherical end piece and is articulated relative to it.

11. A jack as claimed in Claim 9 or Claim 10 in which seats are made nearthe upper extremes of the sections, each said seat containing a guide bushing which is divided into four pieces, said guide bushing having the task of ensuring the perfect running of the telescopic elements.

12. A jack as claimed in Claim 11 in which the upper part of each said guide bushing contains a dust-scraper ring and an oil seal is mounted below each said guide bushing.

13. Ajack as claimed in Claim 12 in which an anti-extrusion ring is interposed between each annu lar oil seal and the adjacent guide bushing, the anti-extrusion ring having the function of isolating the seal from the junctions of the different parts forming the bushing.

14. A jack as claimed in any of Claims 9 to 13 in which a series of guide rings each divided into two pieces is mounted near the lower edges of the sections and a pair of stop rings is mounted at positions corresponding to the extreme end-oftravel positions of each section.

15. A telescopic multi-section lifting jack sub- stantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

16. A vehicle having a tipping body or other vehicle-mounted structure actuated by a jack as claimed in any of Claims 1 to 15.