GB2426752A

GB2426752A - Lifting apparatus for immersing articles in a tank of cleansing fluid

Info

Publication number: GB2426752A
Application number: GB0610865A
Authority: GB
Inventors: David Williamson
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-02
Filing date: 2006-06-02
Publication date: 2006-12-06
Anticipated expiration: 2026-06-02
Also published as: GB0610865D0; GB0511220D0; GB2426752B

Abstract

A lifting apparatus for use with a tank (1) for cleaning articles in a cleansing fluid, has a lever (38) capable of moving about a fulcrum (40) from a first position to a second position, a horizontally disposed support frame (12) for supporting articles to be cleaned and a cable and pulley system (20) which interconnects the lever (38) and the support frame (12). The cable and pulley system is formed and arranged so that when the lever (38) moves between the first position and the second position, the arcuate motion of the lever (38) about the fulcrum (40) is translated into a corresponding vertical motion of the support frame (12) which lowers the support frame from a first raised position to a second lowered position inside the tank (1) in a substantially horizontal orientation. A tank (1) including the lifting apparatus is also provided.

Description

LIFTING APPARATUS

The present invention relates to a lifting apparatus for use with a tank for immersing articles in a cleansing fluid and to a cleansing tank provided with the lifting apparatus.

Contaminated articles, such as pots and pans with baked or burnt on foodstuffs, or items of chemical process plant, such as valves and pipe fittings often require special cleaning methods. Typically dirty articles are cleaned by immersing them in a cleansing fluid at elevated temperature. The cleansing fluid may be aqueous or non- aqueous and is selected as being the most effective at removing a particular type of contamination. The cleansing fluids employed are often hazardous in nature, being corrosive or toxic for example. Even a non- hazardous fluid such as water presents a hazard at elevated temperatures.

Cleansing operations are often carried out in a tank, which may be heated, containing a cleansing fluid. Placing articles to be cleaned into the tank and retrieving them after cleaning can be awkward and hazardous, requiring an operator to bend over or into the tank whilst bearing the weight of the articles, with risk of strain injury and of contacting or being splashed with the cleansing fluid being used. Tanks containing hot liquids pose the risk of scalds or burns to the operator.

It is an object of the invention to provide means for immersing and retrieving articles to be cleaned from a tank containing cleansing fluid that avoids at least some of the aforementioned problems.

The present invention provides a lifting apparatus for use with a tank for cleaning articles in a cleansing fluid, said lifting apparatus comprising: a lever capable of moving about a fulcrum from a first position to a second position; a horizontally disposed support frame for supporting articles to be cleaned; and a cable and pulley system which interconnects said lever and said support frame; said cable and pulley system being formed and arranged so that, in use of the apparatus, when the lever moves between the first position and the second position, the arcuate motion of the lever about the fulcrum is translated into a corresponding vertical motion of the support frame which lowers the support frame from a first raised position to a second lowered position inside a said tank in a substantially horizontal orientation.

Preferably the movement of the lever from the first position to the second position is from a raised position where the end of the lever is higher than the fulcrum, to a lowered position. Most preferably the movement of the lever about the fulcrum is vertically from a raised position to a horizontal lowered position.

The invention allows an operator to lower articles into cleansing fluid in a tank, whilst avoiding personal contact with the fluid. On moving the lever, articles on the support frame, or in a container on the support frame, are lowered with the support frame into the cleansing fluid.

After the cleaning operation is finished the operator can then move the lever back to its first position to lift the articles on the support frame up out of the cleansing fluid, where they can be allowed to drain, before being removed. Further articles to be cleaned can then be placed on the support frame. Conveniently the lifting apparatus is formed and arranged so that when the lever is in the first position the support frame, in its corresponding first position, is near the top of a tank and when the lever is in the second position the support frame, now in its second position, is lowered to near to the bottom of a tank being used with the apparatus. In the raised position articles can then be placed onto the support frame or a container mounted on the support frame. With the support frame descending to near the bottom of the tank by the movement of the lever, maximum use can be made of the volume of the tank to clean large articles or a number of articles.

Preferably the lever of the invention is formed and arranged so as to be operated manually. The manual operation of the lever may be assisted by the provision of a lifting aid such as, for example, compressed gas telescopic struts, springs or a counterweight.

Alternatively, the lever may also be operated by use of a motor or engine, which connects to the lever.

Preferably the lever is also provided with means for locking it in said first or second position or some predetermined intermediate position. Where a heavy load of articles is being cleaned, locking the lever in the first position avoids accidental lowering of the articles into the tank.

Preferably the pulleys of the cable and pulley system are provided with shields, which pass around part of the circumference of the pulley wheel, close to the outer edge of the wheel. These shields act to prevent cables slipping off a pulley wheel. They also help to prevent jamming of objects, for example an operator's clothing, between a cable and a pulley wheel as the lever is being operated.

Alternatively the pulleys may be located in a suitable housing, which has holes or slots through which the cables pass.

The support frame can be, for example, an arrangement of horizontal bars on which articles for cleaning or a container for such articles can be located. Conveniently, for many applications, a basket is located on the support frame and may be releasably attached to it. Alternatively the support frame may itself be a basket, directly connected to the cables of the cable and pulley system.

Use of a basket or a basket mounted on the support frame has the advantage that a load of articles of different shapes and sizes can simply be put into the basket when the lever is in the raised position. After cleaning, when the basket is raised out of the cleansing fluid the cleansing fluid simply drains out through the mesh of the basket.

Where relatively large articles are being cleaned problems may arise with low-sided baskets. Large articles, not properly located, may overhang the sides of the basket, interfering with operation of the lifting apparatus. On heating in cleansing fluid articles may expand or distort to overhang the sides of the basket and then jam against the tank sides or the pulley and cable system. Desirably baskets for use with the support frame, or used as the support frame are fitted with overspill guards to avoid these problems. The overspill guards take the form of extensions to the height of the basket edges and are located at intervals around the edges of the basket. They act to prevent large articles overhanging the basket edges on loading or during the cleaning operation. For example, the overspill guards may be rectangular loops of steel rod, which project vertically above the basket edges.

Conveniently the overspill guards also act as handles for lifting the basket from the apparatus when desired.

Preferably the support frame and any container or basket used can be constructed of stainless steel. Other metals or alloys thereof, or plastic materials can be used.

Coated, for example painted, materials can also be used, depending on the nature of the cleansing fluid and the temperature of the fluid employed when cleaning.

Preferably the lever and the cable and pulley system are constructed of materials that are compatible with the cleansing conditions. Stainless steel cables, pulleys and lever may be used in the apparatus of the invention. It will be understood that the term cable' used in this description means any suitable flexible line such as a rope, wire or chain, capable of supporting the weight of the support frame and articles to be cleaned. Where the cable is a chain, the pulleys may take the form of sprockets i.e. toothed wheels, to ensure positive engagement between the cables and the pulleys in use of the apparatus.

Preferably a plurality of cables is used in the cable and pulley system and said cables are formed and arranged so that the support frame remains horizontally disposed irrespective of a load applied to it. For example, where a generally rectangular support frame is used four cables can be employed. Each is attached to the support frame near its corners so as to suspend it in a horizontally disposed fashion. By suspending the support frame equally from sufficient spaced apart points near the periphery of its structure it can be prevented from tipping to one side or other when a load (articles to be cleaned) is applied at, for example, one side of the support frame. Additional cables can be employed in the cable and pulley system where heavier loads are to be supported.

Most preferably the cable and pulley system has a plurality of cables each attached in a spaced apart relationship to the support frame and said system is formed and arranged so that the arcuate motion of the lever about the fulcrum produces an equal amount of corresponding vertical motion at each point where a cable is attached to the support frame. This has the effect of maintaining the horizontal disposition of the support frame at all times. All the cable attachment points, from which the frame is suspended, move by the same vertical amount for a given arcuate movement of the lever. This ensures that articles do not move or slip when located on the frame or in a container located on the frame as the lever is operated.

For example, in an apparatus where the lever moves about its fulcrum vertically from a raised position to a horizontal lowered position, equal amounts of vertical motion can be achieved for each cable as follows. Each cable attaches to a point on the lever that is equidistant from the fulcrum and then passes round a corresponding cable distribution pulley. The cable distribution pulleys are positioned so that, for any given position of the lever, the distances between each cable distribution pulley and the corresponding cable attachment point on the lever are substantially the same. This can be done, for example, by having all the cable distribution pulleys located vertically below the corresponding attachment point of the corresponding cable to the lever, when the lever is in its second (horizontal) position. The cables then each pass round a corresponding suspension pulley before attaching to an appropriate point on the support frame.

This arrangement means that when the lever is lowered the length of each cable that passes around each of the distribution pulleys, and then via the suspension pulleys to the support frame, is equal. Therefore each cable lowers the support frame by the same amount, ensuring that it remains horizontally disposed whatever the position of the lever.

Most preferably, where the lever moves vertically about its fulcrum, each attachment point of a cable to the lever and the corresponding attachment point of the cable to the support frame, together with corresponding suspension and cable distribution pulleys, are in the same vertical plane.

This ensures smooth running of the cables round the pulleys.

Conveniently the lever of the lifting apparatus of the invention is a lid for a cleansing tank to be used with the invention and the fulcrum for the lever is a hinge connecting the lid to the tank. Using a hinged lid as the lever of the lifting apparatus of the invention has the advantage that a separate lever arrangement is not required. The second position for the lever (lid) is when the lid is closed and the first position is when the lid is fully open, which may be conveniently be when it is close to vertical. It is desirable to provide a lid for cleansing tanks especially where the cleansing fluid employed is heated and may evaporate or give off noxious fumes. Closing the lid of the tank prevents loss of fluid and also prevents persons contacting the contents or dropping articles inadvertently into the fluid.

Advantageously, where the lever is a lid for the tank, the support frame is near the top of the tank when the lid is open and the support frame or a container placed on the support frame, in use of the apparatus, has substantially the same area as the cross sectional area (in plan) of the tank. This arrangement has the advantage that the support frame (or the container on it) acts as a barrier, to prevent persons reaching into the tank and contacting hot or otherwise harmful fluid in the tank when the lid is open.

According to another aspect of the invention there is provided a tank for holding articles to be cleaned in a cleansing fluid, said tank having a lifting apparatus comprising: a lever capable of moving about a fulcrum from a first position to a second position; a horizontally disposed support frame for supporting articles to be cleaned; and a cable and pulley system which interconnects said lever and said support frame; said cable and pulley system being formed and arranged so that, in use of the apparatus, when the lever moves between the first position and the second position, the arcuate motion of the lever about the fulcrum is translated into a corresponding vertical motion of the support frame which lowers the support frame from a first raised position to a second lowered position which is inside the tank.

Preferably the lever is a lid of the tank and the fulcrum is a hinge about which the lid opens and closes.

Most preferably the tank is cuboid in form and has a lifting apparatus comprising: a lid hinged on one edge to the rear side of the tank as a lever; a horizontally disposed support frame of rectangular form for supporting articles to be cleaned, which has an attachment point for a cable disposed near each corner; and a cable and pulley system which interconnects the lid and the support frame; said cable and pulley system comprising four cables each attached to one of said attachment points on the support frame and each then passing firstly round a corresponding suspension pulley located near a top corner of the tank and mounted on the inside of a side edge of the tank, then round a corresponding cable distribution pulley, the cable distribution pulleys being concentric and mounted in pairs on a side edge of the tank and each cable then being attached to the lid at an attachment point near the side edges of the lid wherein said attachment points are at the same distance from the hinged edge of the lid.

In this arrangement the cable and pulley system is mounted at each side of the tank and its lid. This has the benefit that the lifting apparatus does not interfere with loading and unloading of articles, which is carried out from the front edge of the tank.

The four suspension pulleys near each top corner of the tank provide even support for each of the cables from which the support frame is suspended. The concentric cable distribution pulleys and the attachment of the cables to the lid at the same distance from the hinge ensure that for a given movement of the lid, the arcuate motion is translated into a vertical motion of the same length for all four cables. This maintains the horizontal disposition of the support frame at all times.

The desired equal length of vertical motion of all four cables can be obtained by other means. As an alternative the cable distribution pulleys are not mounted concentrically and in pairs on side edges of the tank, but are mounted in pairs on a side edge with each pulley of a pair adjacent its partner. This arrangement can be used to provide the desired motion of the support frame as described hereinafter with reference to a specific embodiment.

The tank can have different forms and still be fitted with the lifting apparatus. For example, the tank may be cylindrical with a circular cross section and lid. Similar arrangements to those described for a cuboid tank, with cable and pulleys disposed towards opposite parts of the circumference of the tank, are preferred to allow easy access to the interior of the tank.

The attachment points for the cables to the lid are selected to give the desired length of vertical motion for the support frame. Desirably the cable and pulley positioning is selected so that the support frame is near the top of the tank when the lid is in its fully open position and the support frame is lowered to near the bottom of the tank when the lid is closed. This means that an operator can load and unload articles onto the support frame or a container mounted in the support frame without contacting the bulk fluid in the tank, which may be hot and/or corrosive or otherwise harmful.

The maximum vertical drop that can be obtained with a hinged lid acting as a lever is when the cables are attached to the front edge of the lid and the cable distribution pulleys are located at the front of the tank.

This arrangement has the disadvantage that no mechanical advantage is obtained to assist the operator with raising and lowering the lever. Preferably the attachment points to the lid are located between the hinge and the opposite (front) edge. The operator lifts the lid at the opposite edge to the hinge to obtain the mechanical advantage of a second-class lever.

Advantageously the lifting apparatus tank further comprises a lifting aid such as, for example, compressed gas telescopic struts, springs or a counterweight. The lid may also be opened or closed using a motor or engine.

A cleansing tank of the invention will also typically have thermal insulation, a heating system such as electrical heating elements and a drain valve to allow removal of used cleaning fluid from the bottom of the tank.

Further preferred features and advantages of the present invention will appear from the following detailed description of some embodiments illustrated with reference to the accompanying drawings in which: Figure 1(a) is a perspective view of an embodiment of the invention fitted to a cleaning tank; Figure 1(b) shows a basket for holding articles to be cleaned in the tank of figure la; Figs 2(a-d) illustrate schematically the operation of a cable and pulley system of the invention; Figs 3 (a-d) illustrate schematically an alternative cable and pulley arrangement; Fig 4 illustrates use of a cable and pulley system directly connected to a basket; Fig 5 shows a pulley wheel of an embodiment of the invention, fitted with a shield; and Figs 6 (a,b) illustrate schematically a further alternative cable and pulley arrangement.

Figure la shows a rectangular insulated stainless steel tank 1 with a close fitting insulated lid 2, which opens about a hinge 4. The lid 2 is shown in an open position.

The tank 1 is also supplied with internal heating elements operated by a control 6 on the bottom front 8 of the tank which is covered in normal use by a kickplate (not shown) A drain valve 10 for emptying the tank of cleansing fluid when required is also provided at the bottom front of the tank.

A support frame 12 for a basket 14 (shown in figure lb) is fitted to the tank 1. The support frame 12 is a generally rectangular frame constructed of welded stainless steel rod and has four hooks 16 for releasably securing the basket 14 in use. The support 12 is suspended at each corner by a stainless steel cable 18. The basket 14 (not all of its mesh shown for clarity) has overspill guards 19 fitted at the centre of each side. The overspill guards take the form of rectangular loops of steel rod projecting above the basket edges. They also act as handles for lifting the basket onto and from the support frame 12.

The cables 18 are those of a cable and pulley system generally indicated by the reference number 20, which interconnects the lid 2 of the tank to the support frame 12. Each cable 18 passes from a corner of the support frame 12 up and round one of four suspension pulleys 22 sited near each top corner of the tank 1 and then is passed round one of four distribution pulleys 24 mounted in pairs.

The distribution pulleys are concentric and mounted on the inside of the side edges 26 of the tank 1 at a point between the corresponding two suspension pulleys 22, near the top of the tank 1. Each cable 18 then attaches to one of two attachment points 28 mounted part way along each side edge 30 of the lid 2. The lid also has two handles 32 for opening and closing and two compressed gas struts 34 to assist opening of the lid 2.

In use, the tank 1 is filled to an appropriate depth with a cleansing fluid and the fluid heated as required. Articles to be cleaned are then placed in the basket 14 which is mounted on the basket support frame 12 and secured with the hooks 16.

When the tank lid 2 is moved from its open position as shown in Figure 1(a) towards a closed position as indicated by the arrows 36, the basket 14 mounted on the support frame 12 is lowered into the tank 1 as the cables 18 move around the suspension and distribution pulleys (22,24) Following a cleaning operation, when the lid 2 of the tank 1 is raised, the basket 14 is then raised towards the top of the tank as the cables 18 are lifted by the raising of the lid 2 which moves the cable attachment points 28 upwards and backwards in a direction opposite to the arrows 36.

The operation of the lifting mechanism is described in more detail with reference to Figure 2, which shows schematically operation of a lever and pulley mechanism of the invention.

Figure 2 (a) shows a lever 38, which moves about a pivot (fulcrum) 40 and is able to move from vertical to horizontal. A cable 18 is fixed at one end to an attachment point 28 at a distance d from the pivot 40. The cable runs round a distribution pulley 24 and then a suspension pulley 22 near the pivot before attaching at the other end to a basket support frame 12 (shown in Fig 2 (c)) As the lever is lowered in a direction shown by the arrow 36 the cable attachment point 28 moves downwards in an arcuate fashion, allowing the basket support frame 12 suspended from the cable (figure 2(c) ) to lower. The distribution pulley 24 and suspension pulley 22 rotate in directions shown by circular arrows adjacent to each pulley in the figure.

Figure 2(b) shows a similar arrangement to that of figure 2(a) except that the cable 18 passes around a suspension pulley 22 that is distal to the pivot 40 after passing round the distribution pulley 24. When the lever 38 is lowered the rotation of the pulleys is opposite to those of figure 2(a), as shown by the circular arrows.

Figure 2(c) shows the combination of figure 2(a) and figure 2(b) and represents schematically the mechanism shown in Figure 1 (a) at each side of the tank 1. The two distribution pulleys 24 are concentric. The two cables 18 both span the same distance (shown as X) between the attachment point 28 to their distribution pulleys 24.

Accordingly when the lever 38 is lowered (or raised) the distance X changes by the same amount for both cables 18.

At all times the length of each cable 18 fed round the corresponding pulleys 22,24 to the support frame 12 remains the same. This has the effect of ensuring that the support frame 12 is maintained horizontal irrespective of the position of the lever or the loading in a basket placed on the support frame 12. It should be noted that this effect occurs despite differing lengths of the cables 18. In this example the cable 18 that passes round the suspension pulley nearest the pivot (fulcrum) 40 is longer than the cable passing round the suspension pulley 22 distal to the pivot 40.

Figure 2 (d) shows the arrangement of figure 2 (c) except that the lever 38 has been lowered to an almost horizontal position. This corresponds to a tank lid 2 such as in figure 1 being nearly in its closed position. In the position shown in figure 2(d) the basket support frame is close to its maximum distance from the lever i.e. in the case of a device fitted to a tank as in figure 1 the basket support frame is at its lowest when the lid 2 is closed (horizontal) It can be seen from figure 2(d) that the cable attachment point 28 and the distribution pulleys 24 are located at the same distance from the pivot 40. This reduces the amount of the cable used to interconnect the lid to the support frame to the minimum.

The distance the basket support frame 12 is lowered depends on the position of the attachment point 28 on the lever and the position of the distribution pulleys 24. Figure 3 shows the maximum degree of lowering that can be achieved.

The attachment point 28 is at the opposite end of the lever 38 from the pivot (fulcrum) 40 and the distribution pulley 24 is located concentrically with the suspension pulley 22 distal from the pivot 40. As shown in figure 3(b) the suspension pulley 22 distal from the pivot also acts as the distribution pulley 24 for one of the cables in this embodiment. Figure 3(c) shows the combined arrangement of the cables and pulleys with the maximum vertical drop for the support frame shown in figure 3 (d) Figure 4 shows schematically a tank and lifting apparatus arrangement where the support frame 12 is a basket 14, directly attached to the cables 18 of a cable and pulley system.

Figure 5 shows a pulley, in this case a suspension pulley 22, that has a cable 18 passing round it, fitting into the groove on the wheel rim. A shield 42, which is a flange of metal projecting from the side of a tank 26 on which the pulley is located, fits closely about a portion of the pulley wheel circumference 44. This shield 42 acts to prevent the cable 18 slipping from the pulley 22 and also serves to deflect, for example an operators clothing, from jamming between the pulley and the cable.

Figure 6(a) shows schematically a further alternative lever and pulley mechanism to that of Figure 2(c). In this case the cable distribution pulleys 24 are not mounted concentrically but are adjacent each other. The two cables 18 are, as in the arrangement of Figure 2 fixed at one end to an attachment point 28 on the lever 38. Each cable 18 then passes round one of the distribution pulleys 24 and then passes round suspension pulley 22 before attachment to the support frame 12.

On lowering the lever 38 the support frame is lowered to the position as shown in Figure 6(b). The adjacent location of the cable distribution pulleys 24 ensures the support frame is maintained horizontal in the same way as achieved by the arrangement of Figure 2.

It will be appreciated that various modifications can be made to the above described embodiments without departing from the scope of the invention. Thus for example instead of using manual operation of the lid/lever, there may be used a motor either electrically or hydraulically operated.

Claims

1. A lifting apparatus for use with a tank for cleaning articles in a cleansing fluid, said lifting apparatus comprising: a lever capable of moving about a fulcrum from a first position to a second position; a horizontally disposed support frame for supporting articles to be cleaned; and a cable and pulley system which interconnects said lever and said support frame; said cable and pulley system being formed and arranged so that, in use of the apparatus, when the lever moves between the first position and the second position, the arcuate motion of the lever about the fulcrum is translated into a corresponding vertical motion of the support frame which lowers the support frame from a first raised position to a second lowered position inside a said tank in a substantially horizontal orientation.

2. A lifting apparatus according to claim 1 wherein the movement of the lever from the first position to the second position is from a raised position where the end of the lever is higher than the fulcrum, to a lowered position.

3. A lifting apparatus according to claim 2 wherein the movement of the lever about the fulcrum is vertically from a raised position to a horizontal lowered position.

4. A lifting apparatus according to any previous claim formed and arranged so that when the lever is in the first position the support frame, in its corresponding first position, is near the top of a tank and when the lever is in the second position the support frame, now in its second position, is lowered to near to the bottom of a tank being used with the apparatus.

5. A lifting apparatus according to any previous claim wherein the lever is formed and arranged so as to be operated manually.

6. A lifting apparatus according to any previous claim further comprising a lifting aid to assist the operation of the lever.

7. A lifting apparatus according to claim 6 wherein the lifting aid is selected from the group consisting of compressed gas telescopic struts, springs and counterweights.

8. A lifting apparatus according to any one of claims 1 to 4 further comprising a motor or engine which connects to and operates the lever.

9. A lifting apparatus according to any previous claim provided with means for locking the lever in a predetermined position.

10. A lifting apparatus according to any previous claim wherein the pulleys of the cable and pulley system are provided with shields, which pass around part of the circumference of the pulley wheel, close to the outer edge of the wheel.

11. A lifting apparatus according to any one of claims 1 to 9 wherein the pulleys are located in a housing, which has holes or slots through which the cables pass.

12. A lifting apparatus according to any previous claim wherein the support frame is an arrangement of horizontal bars.

13. A lifting apparatus according to any previous claim further comprising a basket for locating on the support frame in use of the apparatus.

14. A lifting apparatus according to claim 13 wherein the basket is relLeasably attachable to the support frame.

15. A lifting apparatus according to any one of claims 1 to 11 wherein the support frame is a basket.

16. A lifting apparatus according to any one of claims 13 to 15 wherein the basket is fitted with overspill guards.

17. A lifting apparatus according to claim 16 wherein the overspill guards are rectangular loops of steel rod projecting vertically above the basket edges.

18. A lifting apparatus according to claim 16 or claim 17 wherein the overspill guards are handles for lifting the basket.

19. A lifting apparatus according to any previous claim wherein the support frame and any container or basket used are constructed of stainless steel.

20. A lifting apparatus according to any previous claim wherein the cables, pulley and lever are stainless steel.

21. A lifting apparatus according to any previous claim wherein the cables of the cable and pulley system are chains and the pulleys are sprockets.

22. A lifting apparatus according to any previous claim wherein a plurality of cables is used in the cable and pulley system and said cables are formed and arranged so that the support frame remains horizontally disposed irrespective of a load applied to it.

23. A lifting apparatus according to claim 22 wherein the cable and pulley system has a plurality of cables each attached in a spaced apart relationship to the support frame and said system is formed and arranged so that the arcuate motion of the lever about the fulcrum produces an equal amount of corresponding vertical motion at each point where a cable is attached to the support frame.

24. A lifting apparatus according to claim 23 wherein the lever moves about its fulcrum vertically from a raised position to a horizontal lowered position and each cable attaches to a point on the lever that is equidistant from the fulcrum and then passes round a corresponding cable distribution pulley, said cable distribution pulleys being positioned so that, for any given position of the lever, the distances between each cable distribution pulley and the corresponding cable attachment point on the lever are substantially the same.

25. A lifting apparatus according to claim 24 wherein each attachment point of a cable to the lever and the corresponding attachment point of the cable to the support frame, together with corresponding suspension and cable distribution pulleys, are in the same vertical plane.

26. A lifting apparatus according to any previous claim wherein the lever of the lifting apparatus of the invention is a lid for a cleansing tank to be used with the invention and the fulcrum for the lever is a hinge connecting the lid to the tank.

27. A lifting apparatus according to claim 26 wherein the support frame is near the top of the tank when the lid is open and the support frame or a container placed on the support frame, in use of the apparatus, has substantially the same area as the cross sectional area, in plan, of the tank.

28. A tank for holding articles to be cleaned in a cleansing fluid, said tank having a lifting apparatus comprising: a lever capable of moving about a fulcrum from a first position to a second position; a horizontally disposed support frame for supporting articles to be cleaned; and a cable and pulley system which interconnects said lever and said support frame; said cable and pulley system being formed and arranged so that, in use of the apparatus, when the lever moves between the first position and the second position, the arcuate motion of the lever about the fulcrum is translated into a corresponding vertical motion of the support frame which lowers the support frame from a first raised position to a second lowered position which is inside the tank.

29. A tank according to claim 28 wherein the lever is a lid of the tank and the fulcrum is a hinge about which the lid opens and closes.

30. A tank according to claim 28 or claim 29 wherein the tank is cuboid in form and has a lifting apparatus comprising: a lid hinged on one edge to the rear side of the tank as a lever; a horizontally disposed support frame of rectangular form for supporting articles to be cleaned, which has an attachment point for a cable disposed near each corner; and a cable and pulley system which interconnects the lid and the support frame; said cable and pulley system comprising four cables each attached to one of said attachment points on the support frame and each then passing firstly round a corresponding suspension pulley located near a top corner of the tank and mounted on the inside of a side edge of the tank, then round a corresponding cable distribution pulley, the cable distribution pulleys being concentric and mounted in pairs on a side edge of the tank and each cable then being attached to the lid at an attachment point near the side edges of the lid wherein said attachment points are at the same distance from the hinged edge of the lid.

31. A tank according to claim 28 or claim 29 wherein the tank is cuboid in form and has a lifting apparatus comprising: a lid hinged on one edge to the rear side of the tank as a lever; a horizontally disposed support frame of rectangular form for supporting articles to be cleaned, which has an attachment point for a cable disposed near each corner; and a cable and pulley system which interconnects the lid and the support frame; said cable and pulley system comprising four cables each attached to one of said attachment points on the support frame and each then passing firstly round a corresponding suspension pulley located near a top corner of the tank and mounted on the inside of a side edge of the tank, then round a corresponding cable distribution pulley, the cable distribution pulleys being mounted in pairs, with each pulley of a pair adjacent its partner, on a side edge of the tank and each cable then being attached to the lid at an attachment point near the side edges of the lid wherein said attachment points are at the same distance from the hinged edge of the lid.

32. A tank according to claim 28 or 29 wherein the tank is cylindrical with a circular cross section and lid.

33. A tank according to any one of claims 28 to 32 wherein the cable and pulley positioning is selected so that the support frame is near the top of the tank when the lid is in its fully open position and the support frame is lowered to near the bottom of the tank when the lid is closed.

34. A tank according to any one of claims 28 to 33 wherein the attachment points to the lid are located between the hinge and the opposite edge.

35. A tank according to any one of claims 28 to 34 further comprising a lifting aid selected from the group consisting of compressed gas telescopic struts, springs and a counterweight.

36. A tank according to any one of claims 28 to 34 wherein the lid is opened or closed using a motor or engine.

37. A tank according to any one of claims 28 to 36 further comprising thermal insulation, a heating system and a drain valve.

38. A lifting apparatus substantially as described hereinbefore and with reference to Fig. 2 of the accompanying drawings.

39. A lifting apparatus substantially as described hereinbefore and with reference to Fig. 3 of the accompanying drawings.

40. A lifting apparatus substantially as described hereinbefore and with reference to Fig. 6 of the accompanying drawings.

41. A tank for holding articles to be cleaned substantially as described hereinbefore and with reference to Fig. 1 of the accompanying drawings.