GB2352204A

GB2352204A - Lifting tool

Info

Publication number: GB2352204A
Application number: GB0008847A
Authority: GB
Inventors: Christopher John Kendall
Original assignee: MG Rover Group Ltd
Current assignee: MG Rover Group Ltd
Priority date: 1999-05-12
Filing date: 2000-04-12
Publication date: 2001-01-24
Also published as: GB0008847D0; GB9910904D0

Abstract

A lifting tool for a body eg an inspection cover has a key end 6 with a transverse projection 8 for passage through an elongate aperture 11, 12 in the body where it is turned for engagement. A locking member, eg bolt 14, being extensible into the aperture to prevent rotation and disengagement.

Description

2352204 A Lifting Tool The present invention relates to a lifting tool and

more particularly to a lifting tool such as might be used to lift inspection covers in a factory.

Inspection covers are commonly provided for suspended flooring and underground conduits to allow access to spaces where cabling and other functional apparatus may be located. Typically, these inspection covers comprise a flat plate which is arranged to he over an inspection pit within the suspended flooring or conduit. In order to allow these inspection covers to be lifted they are typically provided with key apertures such as a hole with diametrically opposed slots to allow the insertion of a lifting tool comprising a round section bar with transverse lugs, the lugs passing through the slots and engaging an underside of the cover when the lifting tool is given a quarter turn.

Inspection covers are generally of a significant weight in order to carry appropriate loads and to avoid inadvertent displacement. In such circumstances, it is necessary that the engagement between the lifting tool and the lifting cover is sufficient robust to resist dislocation during the lifting process. If the inspection cover were to become dislodged from the lifting tool then this cover could cause injury or damage. With cast iron covers it is relatively easy to provide a cam profile on the undersurface of the cover to provide a more positive engagement with the lugs of the lifting tool but this is less easy to provide with covers made from plate stock, e.g. chequer plate, as used for factory equipment where there is less scope for standard sizes of cover.

It is an object of the present invention to provide an improved lifting tool which can provide positive location of the lifting tool in a body such as an inspection cover.

In accordance with the present invention there is provided a lifting tool for a body such as an inspection cover, the tool comprising a lift member having a key end and a lift end, the key end having an elongate portion and at least one transverse projection, the key end being in use aligned with a key aperture in the body and inserted axially through the aperture whilst in one, free, angular orientation and rotated into another, engaged, angular orientation to enable the or each transverse projection to engage an undersurface of the body, the key aperture being shaped with an orifice for the passage of the elongate portion and a slot or slots for passage of the or each transverse projection, the tool including a locking member carried by the lift member and having blocking means thereon for engagement with the aperture, the locking member being slidable between a locked position where the blocking means can engage the or at least one slot to prevent rotation of the lift member away from the engaged orientation and a retracted position where it is clear of the key aperture to allow the lift member to be rotated to the free orientation and withdrawn from the aperture.

Conveniently, the blocking means comprises at least one longitudinal projection. Preferably, there are two of said transverse projections diametrically opposed on the key end, the longitudinal projection being arranged substantially perpendicularly to the transverse projections.

Preferably, the locking member is spring biased into the locking position, in which case the tool may include a handle to enable the locking member to be moved against the spring bias to allow extraction of the blocking means from the aperture. The handle may be on the locking member. Alternatively, the handle may be on the lift member and linked to the locking member.

In a preferred arrangement, the locking member is a bolt arranged to he flush with the lift member, in which case the bolt may be guided by guide loops secured to the lift member. The spring bias may conveniently be provided by a compression spring acting between one of the guide loops and a collar secured to the bolt.

Conveniently, the key end is formed from round bar, as may the bolt.

As an alternative to the bolt, the locking member may be tubular and arranged concentrically of the lift member. Such a locking member may have a longitudinal slot which is engaged by a peg in the lift member in order to prevent rotation of the locking member. Also, the spring bias may be provided by a spring arranged concentrically of the lift member.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, of which: Fig,I is a perspective view of a lifting tool according to the invention engaged in an inspection cover; Fig.2 is a perspective view of one end the lifting tool shown in Fig. 1; Fig.3 is a plan view of a portion of the inspection cover shown in Fig.1 illustrating a key aperture in the inspection cover; and Fig.4 is a schematic cross-section of part of the lifting tool shown in Fig.1 engaged in the inspection cover just prior to lifting.

A lifting tool 1 is arranged to engage a body in the form of an inspection cover 2 which extends over an aperture 3 in a suspended floor 4. Typically, the floor aperture 3 includes a ledge 5 upon which the cover 2 rests such that an upper surface of the cover 2 lies substantially level with the floor 4.

The cover 2 includes a key aperture 10 for engagement by a key end 6 of the lifting tool I to enable the lifting operation by application of a lifting force in the direction of arrow A to remove the cover 2 from the floor aperture 3. The lifting tool comprises an elongate lift member 7 of round section bar with a round section cross bar 8 located and welded in a cross drilling at the key end 6 to provide two diametrically opposed transverse projections or lugs.

A locking member in the form of a bolt 14 formed of round section bar stock is carried by the lift member 7 adjacent the key end 6 by guide loops 15, 16 welded to the lift member 7, the bolt lying substantially midway between the lugs of the cross bar 8 so as to be perpendicular to it. A helical compression spring 19 is located around the bolt 14 to act between the upper guide loop 16 and a collar 18 secured to the bolt 14 by grubscrews. The bolt 14 is bent to form a handle. A stop in the form of a setscrew or a blob of weld is provided to limit movement of the bolt under the bias of the spring 19, although this may be omitted and the collar 18 act as such a stop.

Between the guide loops 15 and 16, the lift member 6 has a flat or a shallow groove machined in it to provide clearance for the spring 19 and the collar 18. This allows the bolt 14 to he flush with the lift member 7.

The key aperture 10 has a shape comprising a circular orifice 12 of a diameter which provides clearance for the key end 6 and diametrically opposed slots 11 which correspond to and provide clearance for the lugs of the cross bar 8.

In use, the lifting tool 1 will have its key end 6 aligned with the key aperture and orientated so that the cross bar 8 is aligned with the slots1l. The bolt 14 abuts the cover so that when the lifting tool is pressed down, the key end 6 with the cross bar 8 enters the key aperture 10 and the bolt 14 is slid upwards relative to the lifting tool against the bias of the spring 19. Having entered the key aperture 10 to the extent that the cross bar 8 has emerged from the other side of the plate 2, the lifting tool I is turned a quarter turn, i.e. 90, into an engaged orientation where the lugs of the cross bar can abut the underside of the cover 2. Once so engaged, the bolt 14 can move downwards and a tip portion 22 of the bolt 14 engage one of the slots in the key aperture 10. The tip portion 22 acts as blocking means to stop further rotation of the key end 6 and therefore hold the lifting tool securely in the key aperture 10.

In order to remove the key end 6 from the aperture 10, the bolt 14 is lifted against the bias of the spring 19 such that the tip portion 22 is removed from engagement with the key aperture 10. Thus, the lifting tool I can again be rotated back to align the cross bar 8 with the slots 11 and to allow the key end 6 to be lifted out of engagement with the cover 2.

It will be appreciated that when the bolt is engaged in the aperture it springs back to the position as shown in Fig.2 and thus gives a visual and an audible indication that the tool 1 is properly engaged.

In order to enable appropriate lifting, it will be understood that generally at an opposed or lift end of the lifting tool I from the key end 6 there will be located a lift handle 30 in the form of a perpendicular bar. This lift handle 30 will allow application of an appropriate lift force to enable lifting of the cover body 2. Alternatively, the lift end 30 could comprise an appropriate anchor to enable a mechanical lifting device such as a crane or lifting frame to be used.

Two bolts 14 can be located either side of the cross bar 8 to engage both of the slots 11 of the key aperture 10. This may provide better retention of the lifting tool I within the key aperture 10, particularly in the case of worn or slightly damaged components. In such circumstances, the bolts are typically arranged to be diametrically opposite each other and perpendicular to the axis of the cross bar 8.

As an alternative to use of a bolt 14, a locking member in the form of a substantially tubular sleeve could be located coaxially on the key end 6 with a bifurcated end to provide locking projections. A spring, also concentric with the key end 6, would bias the sleeve towards the key end and a longitudinal slot in the sleeve would engage with a peg in the key end 6 to prevent rotation of the sleeve but allow axial shding movement.

A separate handle or lever may be provided on or near the handle 30 to avoid bending to use the lift handle 21. Such a handle or lever may be linked to the bolt by a rod or a Bowden cable. Furthermore, if desired, a retainer mechanism may be provided to hold the bolt against the load of the spring 19 to allow easier insertion of the tool 1 in the key aperture 10.

Claims

7CLAIMS

1. A lifting tool for a body such as an inspection cover, the tool comprising a lift member having a key end and a lift end, the key end having an elongate portion and at least one transverse projection, the key end being in use aligned with a key aperture in the body and inserted axially through the aperture whilst in one, free, angular orientation and rotated into another, engaged, angular orientation to enable the or each transverse projection to engage an undersurface of the body, the key aperture being shaped with an orifice for the passage of the elongate portion and a slot or slots for passage of the or each transverse projection, the tool including a locking member carried by the lift member and having blocking means thereon for engagement with the aperture, the locking member being shdable between a locked position where the blocking means can engage the or at least one slot to prevent rotation of the lift member away from the engaged orientation and a retracted position where it is clear of the key aperture to allow the lift member to be rotated to the free orientation and withdrawn from the aperture.

2. A tool as claimed in claim 1 wherein the blocking means comprises at least one longitudinal projection..

3. A tool as claimed in claim 2 wherein there are two of said transverse projections diametrically opposed on the key end and the longitudinal projection is arranged substantially perpendicularly to the transverse projections.

4. A tool as claimed in any preceding claim wherein the locking member is spring biased into the locking position, 8 -

5. A too I as claimed in claim 4 and including a handle to enable the locking member to be moved against the spring bias to allow extraction of the blocking means from the aperture.

6. A tool as claimed in claim 5 wherein the handle is on the locking member.

7. A tool as claimed in claim 5 wherein the handle is on the lift member and linked to the locking member.

8. A tool as claimed in any preceding claim wherein the locking member is a bolt arranged to lie flush with the lift member.

9. A tool as claimed in claim 8 wherein the bolt is guided by guide loops secured to the lift member.

10. A tool as claimed in claim 8 when dependent on claim 4 wherein the spring bias is provided by a compression spring acting between one of the guide loops and a collar secured to the bolt.

11. A tool as claimed in any preceding claim wherein the key end is formed from round bar.

12. A tool as claimed in claim 8 or any claim dependant therefrom wherein the bolt is formed from round bar.

13. A tool as claimed in any of claims 1 to 7 wherein the locking member is tubular and arranged concentrically of the lift member.

14. A tool as claimed in claim 13 wherein the locking member has a longitudinal slot which is engaged by a peg in the lift member.

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15. A tool as claimed in claim 13 or claim 14 when dependent on claim 4 wherein the spring bias is provided by a spring arranged concentrically of the lift member.

16. A lifting tool substantially as hereinbefore described with reference to the accompanying drawings.

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