GB2095208A - Method of and device for lifting loads - Google Patents

Abstract

Loads are lifted by a device 1 having a tubular body which slides down a guide line (20, 25) depending to the load (26). The body has a suspender (21) and a hoist (23) attached at longitudinally spaced positions for respectively lowering and raising it. When the hoist is tensioned with the body in its lowered position, the body pivots so that abutment locating means engages an abutment on the guide line or load causing the load to be lifted together with the body. Usually, the guide line comprises a chain (20) attached to the load and the abutment locating means is a chain-receiving slot. The device is of particular use for lifting submersible pumps. <IMAGE>

Description

SPECIFICATION Method of and apparatus for lifting loads The present invention relates to the lifting of loads and has particular, but not exclusive, application to the iifting of submersible pumps.

The invention provides a method of lifting a load located at the end of a depending guide line and a device for use in carrying out that method.

Improvements in seal technology and manufacturing techniques have led in recent years to the extensive use of fully submersible pumps. In such applications as water and sewage pumping, the pumps are located in wet wells having, for example, an average depth of about 5 metres.

Whilst the pumps are reliable, it is necessary for them to be removed from the weíl from time to time for repair or preventative maintenance.

However, the retrieval of the submerged pump from its wet weíl does present problems.

The submersible pump is almost invariably lowered onto its suspension coupling by means of a positioning line such as a chain or wire rope.

After lowering and engaging the discharge flange of the pump, the line is slackened and, for convenience, is left attached to the well wall above top water level. Present systems of retrieval employ either pulley blocks and shear legs or a lifting davit. Depending upon the size and depth of the wet well, the pump can rarely be observed from ground level. Circumstances frequently preclude the wet well from being pumped dry prior to the pump retrieval operation. Usually, it is not possible to attach a lifting hook directly to the pumpe whilst it is submerged and consequently the pump retrieval operation commences by attaching a hook to the positioning line above ground level. The extent of the lift then is governed by the potential hook height measured from ground level. This leads invariably to the need for stage lifting.The pump is raised by an amount equal to the hook height, the positioning íine is then "barred" using either a shackle or ring to sustain the pump while the lifting tackle hook is attached for the next stage of lifting. The raising of the pump in stages is time consuming and usually requires two persons to ensure safety of both lifting equipment and personnel.

A device of simple construction has now been devised which permits the retrieval of a submersible pump from a wet well in a single lifting operation. The device significantly reduces the retrieval time with no attendant reduction in safety of the apparatus or personnel. However, the invention is not restricted to the retrieval of submersible pumps.

According to one aspect of the present invention, there is provided a lifting device for lifting a load located at the lower end of a depending guide line, said device comprising: a tubular body receiving and slidable down said guide line: suspender attachment means for attaching the tubular body to a suspender to lower said body down the guide line to a lowered position; hoist attachment means spaced longitudinally, with respect to the tubular body, from the suspender attachment means, for attaching the tubular body to a hoist to raise said body from said lowered position; and abutment locating means for engagement, in said lowered position, with an abutment on the íoad or guide line to lift the load together with the tubular body, the arrangement being such that, in said lowered position, the tubular body can be pivoted by tensioning the hoist and thereby the abutment locating means engaged with the abutment.

In a presently preferred embodiment of the first aspect of the invention, there is provided a sliding chain clutch, said clutch comprising: a tubular body receiving and slidable down a depending chain; suspender attachment means for attaching the tubular body to a suspender to lower said body down the chain to a lowered position; hoist attachment means spaced longitudinally, with respect to the tubular body, from the suspender attachment means, for attaching the tubular body to a hoist to raise said body from said lowered position; and abutment locating means for engagement, in said lowered position, with one or more chain links to lift the chain together with the tubular body.

the arrangement being such that, in said lowered position, the tubular body can be pivoted by tensioning the hoist and thereby the abutment locating means engaged with the chain link(s).

According to a second aspect of the present invention, there is provided a method of lifting a load located at the end of a depending guide line, which comprises locating the guide line in a tubular body of a lifting device having a suspender and hoist attached thereto at longitudinally spaced positions of said body, iowering said body down the guide line by said suspender, tensioning the hoist to cause said body to pivot whereby abutment locating means of said device engages an abutment on the load or guide line permitting the load to be lifted together with said body, and lifting the body by the hoist.

It is preferred that the suspender attachment means and hoist attachment means are located at opposite ends of the tubular body. it is also preferred that said means are located on opposite sides of the tubular body. Conveniently, said means each comprise a respective lug having an eye-hole to which the suspension or hoist respectively can be attached by, for example, a clip or hook. The suspender and hoist each can be constituted by, for example, a respective chain wire or, more usually, rope.

The abutment locating means can be, for example, a projection on the tubular body adapted to engage the abutment on the load or guide line.

More usually, the abutment means will comprise an open-ended slot in the tubular body. The said slot preferably is on the opposite side of the tubular body to the hoist attachment means and.

inthatcase,itisfurtherpreferredthatthetu body should have a cut away portion at one end converging to the mouth of the slot. When a slot is provided in the tubular body, the abutment will be received in the body and supported by the body wall.

As indicated previously, it is preferred that the guide line should comprise a chain secured to the load. In this case, one or more of the chain links preferably constitute the abutment. The arrangement of adjacent chain links at right-angles means that the provision of a slot as described above is a simple and effective manner of engaging the chain to lift the load. It will be appreciated that it is unnecessary for the chain to extend the whole length of the guide line because only a portion of chain immediately adjacent a load is employed for the lifting operation. This represents a substantial cost saving in the provision of submerged pumps in wet wells because the positioning line need no longer be constituted by a full length of corrosion resistant chain or wire rope.The positioning line can be constituted by a short length of corrosion resistant chain attached directly to the pump and the remaining length of the positioning line can be constituted by a rope of nylon or similar material.

In this connection, it is advantageous that the lifting device should be such that the abutment locating means can be disengaged from the abutment on pivoting of the tubular body by tensioning of the suspender.

Preferably, the suspender attachment means, hoist attachment means and abutment locating means of the lifting device are integral with the tubular body. Conveniently, the device is cast in high carbon steel but, as will be appreciated, it can be cast or fabricated in other materials.

The dimensions of the device will be chosen having regard to the guide line and/or load with which the device is intended to be used. For example, the preferred sliding chain clutch embodiment of the invention can be provided in a selection of sizes for use with 6 mm, 9 mm, 12 mm diameter chain links and/or other standard chain sizes. Whilst the invention is not restricted to a particular shape of the tubular body, it is presently preferred that the tubular body is a right circular cylinder.

The following is a description, by way of example only and with reference to the drawings, of a lifting device in accordance with a present preferred embodiment of the invention. In the drawings: Figure 1 is a perspective view of a sliding chain clutch in accordance with the invention; Figures 2 and 3 are diagrammatic side views showing operation of the clutch of Figure 1 to lift a submersible pump; and Figure 4 is a perspective view of the clutch of Figure 1 in its chain-engaging condition with part of the tubular body cut away.

Referring to the drawings, a sliding chain clutch generally indicated at 1 comprises a right circular tubular body 2 having a planar upper end 3. The lower end 4 of the body is cut away at 5 to converge to the mouth of an axially extending slot 6. An upper lug 7 having an eye-hole 8 is provided at the upper end of the body in axial alignment with the slot 6. A lower lug 9 having an eye-hole 10 is provided diametrically opposite the slot 6 and lug 7.

The clutch 1 is cast integrally from high carbon steel and the internal diameter of the body 2 and width of the slot 6 are determined having regard to the size of the chain 20 (see Figures 2, 3 and 4) with which the clutch is intended to be used.

In use, a nylon rope or other suspender 21 is connected to lug 7 by means of a hook 22 (see Figure 4). Similarly, a hoist wire 23 is attached by a hook 24 to the lug 9. A rope 25 attached to the chain 20 is passed upwardly through the tubular body 2. In the application shown in Figures 2 and 3, the chain 20 and rope 25 together constitute the positioning line of a pump 26 submerged in a wet well (not shown). The device 1 is lowered down the pump positioning line 20, 25 by means by the suspender 21 which retains the device in an essentially upright attitude (see Figure 2).

During the lowering of the device, the hoist wire 23 is freely played out from, for example, a davit.

The device is lowered to a position just above the pump 26 where the chain 20 extends through the tubular body. In this position, the hoist wire is tensioned causing the body to pivot until the chain 20 is engaged in the slot 6 (see Figures 3 and 4).

In this position, hauling in of the hoist wire 23 lifts the pump 26 because the link structure of the chain 20 prevents the chain from passing through the slot 6.

The pump 26 or a replacement pump can be lowered into the wet well by reversing the retrieval procedure described above. In this case, when the pump is in position, the suspender 21 is tensioned causing the tubular body 2 to pivot to an essentially upright attitude thereby allowing the chain 20 to fall from the slot 6.

It will be appreciated that the invention is not restricted to the particular details described above and that numerous modifications and variations can be made without departing from the scope of the invention as defined in the following Claims.

For example, the pump body could be provided with a "T" shaped abutment for engagement in the slot 6.

Claims (14)

1. A lifting device for lifting a load located at the lower end of a depending guide line, said device comprising: a tubular body receiving and slidable down said guide line; suspender attachment means for attaching the tubular body to a suspender to lower said body down the guide line to a lowered position; hoist attachment means spaced longitudinally, with respect to the tubular body, from the suspender attachment means, for attaching the tubular body to a hoist to raise said body from said lowered position; and abutment locating means for engagement, in said lowered position, with an abutment on the load or guide line to lift the load together with the tubular body, the arrangement being such that, in said lowered position, the tubular body can be pivoted by tensioning the hoist and thereby the abutment locating means engaged with the abutment.

2. A lifting device as claimed in Claim 1 which is a sliding chain clutch, said clutch comprising: a tubular body receiving and slidable down a depending chain; suspender attachment means for attaching the tubular body to a suspender to lower said body down the chain to a lowered position; hoist attachment means spaced longitudinally, with respect to the tubular body, from the suspender attachment means, for attaching the tubular body to a hoist to raise said body from said lowered position; and abutment locating means for engagement, in said lowered position, with one or more chain links to lift the chain together with the tubular body, the arrangement being such that, in said lowered position, the tubular body can be pivoted by tensioning the hoist and thereby the abutment locating means engaged with the chain link(s).

3. A device as claimed in Claim 1 or Claim 2, wherein the suspender attachment means and hoist attachment means are located at opposite ends of the tubular body.

4. A device as claimed in any one of the preceding Claims, wherein the suspender attachment means and hoist attachment means are located on opposite sides of the tubular body.

5. A device as claimed in any one of the preceding Claims, wherein the suspender attachment means and hoist attachment means each comprise a respective jug having an eyehole.

6. A device as claimed in any one of the preceding Claims, wherein the suspender attachment means, hoist attachment means and abutment locating means are integral with the tubular body.

7. A device as claimed in any one of the preceding Claims, wherein the abutment locating means comprises an open-ended slot in the tubular body.

8. A device as claimed in Claim 7, wherein said slot is on the opposite side of the tubular body to the hoist attachment means.

9. A device as claimed in Claim 8, wherein the tubular body has a cut-away portion at one end converging to the mouth of said slot.

10. A device as claimed in any one of the preceding Claims, wherein the tubular body is a right circular tube.

11. A device as claimed in Claim 1 and substantially as hereinbefore described with reference to and shown in the drawings.

12. A lifting device as claimed in any one of the preceding Claims in combination with a suspender and a hoist attached respectively to the suspender attachment means and a hoist attachment means.

13. A method of lifting a load located at the end of a depending guide line, which comprises locating the guide line in a tubular body of a lifting device having a suspender and a hoist attached thereto at longitudinally spaced positions of said body, lowering said body down the guide line by said suspender, tensioning the hoist to cause said body to pivot whereby abutment locating means of said device engages an abutment on the load or guide line permitting the load to be lifted together with said body, and lifting the body by the hoist.

14. A method as claimed in Claim 13, wherein said guide line comprises a chain secured to the load and said abutment locating means engages one or more links of said chain.

1 5. A method as claimed in Claim 14, wherein said abutment locating means comprises a chainreceiving slot.

1 6. A method as claimed in any one of Claims 13 to 15, wherein said device is as claimed in any one of Claims 1 to 11.

1 7. A method as claimed in Claim 13 substantially as hereinbefore described with reference to the drawings.

1 8. A method as claimed in any one of Claims 13 to 17, wherein the load is a submersible pump.