GB2207412A

GB2207412A - Apparatus for lifting and transporting paving slabs or similar objects

Info

Publication number: GB2207412A
Application number: GB08718262A
Authority: GB
Inventors: Alec Arthur Witts
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-08-01
Filing date: 1987-08-01
Publication date: 1989-02-01
Anticipated expiration: 2007-08-01
Also published as: GB2207412B; GB8718262D0

Abstract

Apparatus for lifting and transporting paving slabs or similar objects comprises a two-wheeled trolley 10 having a cantilevered support beam 15 projecting laterally therefrom, and an operating handle 16 for raising and lowering the support beam 15. An intermediate element 20 is pivotally mounted on the support beam 15, and two lifting arms 24, 25 each have one end pivotally mounted on the intermediate element and a free end carrying a gripping element 28, 29 for engagement with a side edge of a slab. In operation, the trolley is wheeled to a position where the support beam 15 extends partly across the slab to be lifted, and the beam is then lowered so that the gripping elements 28, 29 on the arms are brought into engagement with opposite side edges of the slab. As the support beam is then raised, the weight of the slab engaging the gripping elements causes the lifting arms 24, 25 to swing downwardly, causing the gripping elements to grip the side edges of the slab so that the slab is raised. <IMAGE>

Description

"Apparatus for lifting and transporting paving slabs or similar objects" The invention relates to apparatus for lifting and transporting paving slabs or similar objects.

Paving slabs, whether made of concrete or of natural stone, are usually heavy and it may therefore be difficult for one man to lift and transport a slab, particularly if it is large. One form of mechanical device for facilitating the handling of such slabs comprises a support bar, having a handle at each end, on which are slidably mounted adjustable retaining arms which are brought into engagement with the opposite edges of the slab. The slab may then be lifted by two men, one gripping each handle of the device. Such device therefore still requires two men to handle the slab.

A more elaborate known device, which enables a slab to be lifted and transported by one man, comprises a wheeled trolley on which a large suction head is mounted so as to be vertically movable. The suction head is lowered on to the upper surface of the slab, the suction is applied by means of an air pump, and the suction head is then raised, lifting the slab from the ground, so that it may then be transported using the trolley. Such a device is expensive to manufacture, and it is also not particularly effective in use since paving slabs tend to have uneven surfaces which may carry foreign bodies thus making it difficult to establish the effective seal necessary for suction. Should the suction be broken when the slab has been lifted from the ground, the slab will fall and may break.

The present invention therefore sets out to provide an improved apparatus for lifting and transporting paving slabs which may be entirely mechanical in operation, which is cheap and easy to manufacture from readily available materials, and which is easy and robust in use.

For convenience, reference will be made throughout this specification to "slabs" since the invention is primarily applicable to the handling of stone or concrete paving slabs. However, it is to be understood that such term is intended to include any objects of generally comparable configuration, such as, for example, metal plates, man-hole covers, timber panels or the like.

According to the invention there is provided apparatus for lifting and transporting paving slabs or similar objects, comprising a wheeled trolley, a cantilevered support structure mounted on the trolley and projecting laterally therefrom, an operating lever arm for raising and lowering the support structure, two lifting arms each having one end mounted on the support structure and a free end carrying a gripping element for engagement with a side edge of a slab, the arms extending in generally opposite directions towards their free ends, and at least one of the arms being so mounted on the support structure that it may swing up and down relatively thereto.

In operation, the trolley is wheeled to a position where the cantilevered support structure extends partly across the slab to be lifted, and the support structure is then lowered and the gripping elements on the arms are brought into engagement with opposite side edges of the slab. As the support structure is then raised, the weight of the slab engaging the gripping elements causes the swinging lifting arm, or arms, to tend to swing downwardly which causes the gripping elements to be pressed more firmly into engagement with the side edges of the slab so that the slab is gripped and raised. The trolley may then be wheeled to a required location and the slab deposited on the ground by lowering the support structure.

Preferably both lifting arms are so mounted on the support structure that they may swing up and down relatively thereto. For example, each arm may be pivotally mounted at said one end thereof.

The support structure may include a support beam and an intermediate member pivotally mounted on the support beam, the lifting arms being pivotally mounted on the intermediate member.

Preferably the pivot axes of the intermediate member and the lifting arms are substantially parallel.

In this case the pivot axes of the lifting arms may be spaced apart, and so located with respect to one another, and to the pivot axes of the intermediate member, that downward pivoting of the intermediate member displaces the pivot axes of the lifting arms relatively to one another horizontally in a direction tending to draw the gripping elements on the arms towards one another. For example, the pivot axes of the lifting arms may be disposed generally one above the other, both axes being spaced horizontally from the pivot axis of the intermediate member. This arrangement has the effect of increasing the mechanical advantage in transmitting the weight of the slab to the gripping action of the gripping elements and thus improves their grip on the slab.

Preferably the intermediate member is provided with an abutment which is engageable with the upper surface of a slab being held between the gripping elements, such engagement limiting pivoting movement of the intermediate member relatively to the slab. This improves tile stability of the slab when suspended from the lifting arms. Preferably also, stop means are provided for limiting pivoting movement of the intermediate member relatively to the support arm.

A manually operable lifting device may be connected to at least one of said arms to disengage its gripping element from a slab when the slab is resting on the ground. This prevents the slab being picked up again when it is desired to raise the lifting arms without also lifting the slab. For example, the lifting device may comprise a sheathed cable, the outer sheath of the cable being connected to the support structure and one end of the inner cable being connected to the lifting arm, an operating member being connected to the opposite end of the cable.

The gripping elements may be adjustably mounted on their respective lifting arms so as to be locatable in alternative positions along the arms. Similarly, the intermediate member may be pivotally mounted on a member which is adjustable to alternative positions along the support beam.

In any of the above arrangements the support structure preferably extends laterally substantially at right angles to the axis of rotation of the wheels of the wheeled trolley. The trolley is preferably a two-wheeled trolley, and in this case the operating lever arm for raising and lowering the support structure may simply be rigidly connected to the support structure and extending to the opposite side of the wheel axis. The support structure may then be raised or lowered by simply swinging the operating lever arm up or down about the wheel axis.

The following is a more detailed < description of a preferred embodiment of the invention, by way of example, reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic side elevation of an apparatus according to the invention shown being engaged with a paving slab, and Figure 2 shows the apparatus carrying a slab after it has been lifted from the ground.

The apparatus comprises a simple two-wheeled trolley 10 comprising two generally triangular legs 11 disposed in the general configuration of an inverted V, the upper ends of the legs being connected by a narrow flat horizontal strip 12. The legs 11 and strip 12 may conveniently be bent from a single sheet of steel.

The lower ends of the legs 11 provide bearings for an axle 13 carrying rubber-tyred wheels 14.

A support beam 15, which may conveniently be of hollow box-section steel, is welded at one end to the horizontal part 12 of the trolley and extends generally horizontally laterally from the trolley, at right angles to the wheel axle 13. An operating lever arm 16, also of hollow box-section steel, is welded at an upwardly extending angle adjacent one end of the support beam 15 and has mounted at its free end a horizontal handlebar 17 to form a T-shape.

A saddle 18 of inverted U-shape straddles the support beam 15 and is slidable along the beam so that it may be located in any of a number of alternative positions by passing a securing pin 19 through registering holes in the saddle 18 and beam 15.

An intermediate member 20 is pivotally mounted on the saddle 18 and comprises a short bar 21 and a hollow box-section element 23 welded to one end of the bar 21.

The short bar 21 passes between the limbs of the saddle 18 and is pivotally mounted on a pivot pin 22.

The ends of two lifting arms 24 and 25 are disposed within the hollow box-section member 23 where they are pivotally mounted on respective pivot pins 26 and 27. The pivot pins 26 and 27 are disposed generally one above the other. The lifting arms 24 and 25 extend in opposite directions from the intermediate member 20 and mounted on their free ends are gripping elements 28 and 29 respectively. Each gripping element comprises a short length of angle-section steel welded transversely to a box-section member 30 or 31 which is slidable along the respective lifting arm 24 or 25, being secured in a selected position by a pin 32 which engages registering holes in the member and lifting arm.

An operator controlled lifting device is connected to the lifting arm 24 and includes an arm 33 pivotally mounted at one end on the pivot pin 22 and connected to the lifting arm 24, at its opposite end, by a short rigid link 34. Connected to the free end of the arm 33 is the inner core 35 of a Bowden cable, the end of the outer sheath 36 of which is connected to the support beam 15. The cable extends to a position on the operating arm 16 adjacent the handlebar 17 where the inner core is connected to an operating lever 37.

A forwardly projecting abutment plate 38 is welded to the bottom of the intermediate member 20.

Figure 1 shows the position where the trolley has been wheeled to a location adjacent a paving slab 39 and the support beam 15 lowered by raising the handlebar 17. This has brought the lower face of the intermediate member 20 into engagement with the upper surface of the slab and the gripping elements 28 and 29 into engagement with the opposite side edges of the slab. To ensure that the gripping elements engage, or are sufficiently close to, the side edges of the slab the sleeves 30 and 31 may require to be adjusted along the lifting arms 24 and 25, but such adjustment is normally only necessary the first time the apparatus is used with a particular size of slab.

Thereafter the pivoting movement of the lifting arms 24 and 25 will accommodate variations in the width of the slab over a certain range.

To lift the slab the handlebar 17 is pushed downwardly so as to swing the support beam 15 upwardly.

As the support beam is raised the intermediate member 20 automatically swings downwardly relatively to the support beam 15, about the pivot pin 22. This has the effect of displacing the pivot pins 26 and 27, on which the lifting arms are mounted, horizontally relatively to one another.

This displacement draws the gripping elements 28 and 29 towards one another so that they are urged firmly into engagement with the opposite side edges of the slab 39.

As the support beam 15 continues to be raised a point is reached where further downward pivoting movement of the intermediate element 20 is prevented by engagement of the free end 40 of the bar 21 with the underside of the support beam. Continued lifting of the support beam therefore raises the intermediate member 20 bodily and with it the lifting arms 24 and 25 and the slab 39, gripped tightly between the gripping elements 28 and 29.

As the slab 39 is raised from the ground its weight tends to swing the lifting arms 24 and 25 downwardly increasing the grip of the elements 28 and 29 on the side of the slab. Tilting movement of the slab 39, as a result of swinging of the arms 24 and 25, is limited by engagement of the upper surface of the slab by the abutment plate 38, this serving to stabilise the slab. This is the position shown in Figure 2 of the drawings.

The trolley may then be wheeled to the fresh location required for the slab, and the slab deposited on the ground at the location by lifting the handlebar 17 and lowering the support beam 15. When it is required to release the slab in the required location it is necessary to disengage at least one of the gripping elements 28 or 29 manually from the slab since otherwise raising of the support beam 15 would again cause the slab to be gripped and lifted. This is achieved by operating the lever 37 to raise the arm 33 by means of the Bowden cable, this in turn raising the lifting arm 24 to bring the gripping element 28 out of engagement with the side edge of the slab 39. Subsequent raising of the support beam 15 then lifts the other gripping element 29 out of engagement with the slab.

The apparatus thus provides a convenient means whereby one person may with little effort lift and transport a paving slab and place it accurately in a required location. In a store of paving slabs the slabs are normally stacked upright one against another. A slab may thus be conveniently removed from the store by lowering it on to the ground from its upright position against the rest of the slabs, whereupon it may be lifted, transported and lowered in the manner described above.

The apparatus, being entirely mechanical, may be robustly constructed from welded steel and is thus inexpensive to manufacture and reliable in operation, requiring no maintenance.

Although the apparatus described by way of example is self-contained, it will be appreciated that the support structure, and the parts connected thereto, could also be mounted on any existing wheeled vehicle instead of on a purpose-built trolley. For example, it could be mounted on a JCB, a dumper truck or any other suitable wheeled vehicle. The above references to a wheeled trolley therefore include such vehicles.

The invention also includes within its scope apparatus suitable for mounting on an existing wheeled vehicle and comprising a cantilevered support structure for mounting on the vehicle to project laterally therefrom, an operating lever arm for raising and lowering the support structure, two lifting arms each having one end mounted on the support structure and a free end carrying a gripping element for engagement with a side edge of a slab, the arms extending in generally opposite directions towards their free ends, and at least one of the arms being so mounted on the support structure that it may swing up and down relatively thereto.

Claims

1. Apparatus for lifting and transporting paving slabs or similar objects, comprising a wheeled trolley, a cantilevered support structure mounted on the trolley and projecting laterally therefrom, an operating lever arm for raising and lowering the support structure, two lifting arms each having one end mounted on the support structure and a free end carrying a gripping element for engagement with a side edge of a slab, the arms extending in generally opposite directions towards their free ends, and at least one of the arms being so mounted on the support structure that it may swing up and down relatively thereto.

2. Apparatus according to Claim 1, wherein both lifting arms are so mounted on the support structure that they may swing up and down relatively thereto.

3. Apparatus according to Claim 2, wherein each arm is pivotally mounted at said one end thereof.

4. Apparatus according to Claim 3; > wherein the support structure includes a support beam 'and an intermediate member pivotally mounted on the support beam, the lifting arms being pivotally mounted on the intermediate member.

5. Apparatus according to Claim 4, wherein the pivot axes of the intermediate member and the lifting arms are substantially parallel.

6. Apparatus according to Claim 5, wherein the pivot axes of the lifting arms are spaced apart, and so located with respect to one another, and to the pivot axes of the intermediate member, that downward pivoting of the intermediate member displaces the pivot axes of the lifting arms relatively to one another horizontally in a direction tending to draw the gripping elements on the arms towards one another.

7. Apparatus according to Claim 6, wherein the pivot axes of the lifting arms are disposed generally oneabove the other, both axes being spaced horizontally from the pivot axis of the intermediate member.

8. Apparatus according to any of Claims 4 to 7, wherein the intermediate member is provided with an abutment which is engageable with the upper surface of a slab being held between the gripping elements, such engagement limiting pivoting movement of the intermediate member relatively to the slab.

9. Apparatus according to any of Claims 1 to 8, wherein stop means are provided for limiting pivoting movement of the intermediate member relatively to the support arm.

10. Apparatus according to any of Claims 1 to 9, wherein a manually operable lifting device is connected to at least one of said arms to disengage its gripping element from a slab when the slab is resting on the ground.

11. Apparatus according to Claim 10, wherein the lifting device comprises a sheathed cable, the outer sheath of the cable being connected to the Support structure and one end of the inner cable being operatively coupled to the lifting arm, an operating member being connected to the opposite end of the cable.

12. Apparatus according to any of the preceding claims, wherein the gripping elements may be adjustably mounted on their respective lifting arms so as to be locatable in alternative positions along the arms.

13. Apparatus according to any of the preceding claims, and including an intermediate member, wherein the intermediate member is pivotally mounted on a member which is adjustable' to alternative positions along the support beam.

14. Apparatus according to any of the preceding claims, wherein the support structure extends laterally substantially at right angles to the axis of rotation of the wheels of the wheeled trolley.

15. Apparatus according to any of the preceding claims, wherein the trolley is a two-wheeled trolley, and the operating lever arm for raising and lowering the support structure is rigidly connected to the support structure and extends to the opposite side of the wheel axis.

16. Apparatus for lifting and transporting paving slabs or similar objects, substantially as hereinbefore described with reference to the accompanying drawings.