AU679476B2 - Vertical guiding mechanism - Google Patents

Description

P100/01Il Regulation 3,2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: VERTICAL GUIDING MECHANISM The following statement is a full description of this invention, including the best method of performing it known to us: ri HIM rLC4()4(XU).

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VERTICAL GUIDING MECHANISM FIELD OF THE INVENTION This invention relates to a guiding assembly for maintaining a rotary drive assembly, such as is used in mining and/or fluid thickening operations, in a desired orientation whilst raising or lowering the drive assembly. The invention also relates to a rotary drive lifting assembly which contains such a guiding assembly. Typically these are used in iquid/solids sedimentation to raije and lower rotable rake arms which engage settled solids within the tank and move the solids to a tank bottom outlet.

BACKGROUND OF THE INVENTION Vertical rotary drive shafts are generally fitted with lifting means capable of raising and lowering he drive shaft as required. Normally, the drive shaft is located in slideable engagement with a surrounding sleeve, which serves to assist in maintaining the drive shaft in substantially vertical orientation. The sleeve is engaged with a motor so that, in operation, the motor rotates the sleeve. The sleeve and the drive shaft are connected so rotation of the sleeve also rotates the drive shaft. This connection is typically a sliding guide key arrangement by which drive torque is transmitted from the sleeve to the vertical drive shaft.

These types of devices have many uses in the mining industry and are also used in liquid/solids sedimentation assemblies. Thickeners or settling apparatus are used for solid-liquid separation of slimes, slurries and sludges.

Such settling apparatus generally includes a relatively large settling tank and rotary rakes supported within the tank. The rakes are driven to move settled material to a cecntral area outlet or to the tank periphery outlet.

S* 25 It is well known that the vertical dive shaft connected to the rotary rakes is subjected to very high torques when rotated. Th- degree of torque experienced by the shaft is dependent upon the resistance to rotation experienced by distant portions of the shaft.

This resistance arises primarily as a result of rakes at the end of the shaft encountering resistance as they are rotated ;n a liquid or through settled solids.

Additional stresses are placed upon the shaft when horizontal forces are also brought to bear on the shaft. For instance when the shaft is deflected from its vertical position or where, in thickening operations, different densities of the sludge being raked by the rake arms place sideway pressures on the vertical shaft.

F1IPMELC6WI4701120.9 2.

These torque and horizontal forces on the vertical shaft increase the friction between the shaft and the surrounding vertical sleeve. The amount of friction is proportional to such forces. When the drive shaft is lifted, the lifting means has to overcome these frictional forces in addition to the usual gravitational force. This places additional strain on the lifting means.

In regard to liquid thickener assemblies, most thickeners are fitted with a lifting device which is capable of lifting the vertical shaft and rake arms above their normal operating position when it is desired to limit the torque applied to such vertical shaft and rakes. In this arrangement, the lifting device and the sliding guide key arrangement are adapted so that the irive shaft (and rake arm) may be lifted whilst the sleeve is still able to transmit drive torque to the drive shaft. Under high torque and/or high horizontal pressures, the frictional forces between the shaft and the sliding guide key arrangement may exceed the weight of the shaft and rake arm and require very powerful lifting devices (e.g.

hoists, screw jacks or hydraulic cylinders) to lift the shaft and rake arm.

One type of thickener assembly is column-mounted ie. is generally secured on top of a .rigid column. In such a thickener assembly a rake drive unit is seated on the colunmn, and includes a motor and gear boxes for rotating a cylindrical cage. This cage has one or more vertical legs connected to generally horizontl rake arms. One of the problems with conventional column-mounted thickener assemblies is that large frictional forces S 20 are also experienced as a result of the considerable torque forces experienced by the legs and rake arms as the rake arms are rotated through the liquid (or slurry). Accordingly, when using conventional guiding means for maintaining the cage and legs in generally .vertical orientation whilst raising (or lowering) them, these large frictional forces o increase the amount of lifting force needed by the lifting means and a high powered lifting device is required.

Another lifting device is disclosed in US Patent No. 4,624,787 which uses a pulley system to achieve the desired lift. This arrangement is complex and requires constant mainter;ance of the cable and pulleys.

:°oooo With the above problems in mind, the present invention is directed towards an improved guiding assembly in which lower frictional forces are generated whilst lifting or: lowering a rotary drive assemblies than is the case in the prior art devices.

SUMMARY OF THE INVENTION According to a first embodiment of this invention, there is provided a guiding assembly, for maintaining a rotary drive assembly in a predetermined orientation whilst raising or lowering the drive assembly, said guiding assembly comprising at least one pair of FHPMELC4W047020.9 IC i' vertically spaced substantially parallel arms rotatably mounted on a support structure and rotatably connected to the drive assembly, said support structure being connected to a base support which is positioned proximate sa:id drive assembly.

Preferably, the guiding assembly includes two pairs of vertically spaced substantially parallel arms, each of said pairs of arms being horizontally spaced from and substantially parallel to the other pair of arms.

More preferably, the parallel arms of the guiding assembly are rotatably mounted on the support structure at one end of each of the arms and the arms are rotatably connected to the drive assembly at the other end of each of the arms.

lo Where the guid'ng assembly includes two pairs of vertically spaced substantially parallel arms as described above, each such pair of arms consists of an upper arm and a lower arm.

In order to provide the guiding assembly with greater strength and rigidity it is preferred that the upper arms of the two pairs of arms are connected by a supporting brace and the lower arms of the two pairs of arms are also connected by a supporting brace.

S 15 When the abovementioned rotary drive assembly is raised or lowered and guided by the abovementioned guiding assembly, the substantially parallel arms of the guiding assembly will be caused to rotate about the mountings on the support structure. This will cause the drive assembly to undergo some degree of horizontal displacement by virtue of the arcuate 0.0. motion of distant portions of the substantially parallel arms.

In order to reduce such horizontal displacement of the drive assembly during lifting or lowering of the drive assembly and according to a second embodiment of this invention, here is provided a guiding assembly, for maintaining a rotary drive assembly in a predetermined erentation whilst raising or lowering the drive assembly, said guiding "assembly including: 25 a first pair of vertically spaced substantially parallel arms rotatably mounted on a first support structure; a second pair of vertically spaced substantially parallel arms rotatably mounted on a second support structure opposite the first support structure; an upper link arm connecting upper arms of the first and second pairs of arms, said link arm being rotatably connected to said upper arms; and a lower link arm connecting lower arms of the first and second. pairs of. arms, said R AA link arm being rotatably connected to said lower arms, wherein each link arm is rotatably connected to the drive assembly at a point intermediate the connections between the link arm and the respective arms to which it is connected.

In this second embodiment of the invention it is further preferred that the guiding assembly furthe:r comprises: a third pair of vertically spaced substantially parallel arms rotatably mounted on the first support structure and being horizontally spaced from and substantially parallel to the first pair of arms; a fourth pair of vertically spaced substantially parallel arms rotatably mounted on the second support structure and being horizontally spaced from and substantially parallel to the second pair of arms; an upper link arm connecting upper arms of the third arnd fourth pairs of arms, said link arm being rotatably connected tu said upper arms; a lower link arm connecting lower arms of the third and fourth pairs of arms, said link arm being rotatably connected to said lower arms, wherein each link arm is rotatably connected to the drive assembly at a point intermediate the connections between the link arm and the respective arms to which it is connected.

The two ends of the abovementioned link arms are preferably rotatably connected to ends of the respective parallel arms.

In this second embodiment of the invention, when the drive assembly is lifted or lowered, the substantially parallel arms rotate about their mountings on the relevant support structures. This causes each link arm, positioned between the two upper arms and the two lower arms, respectively, to rise or fall and to rotate relative to the arms to which it is connected. As each link arm rises or falls, the position of the rotatable connection with the drive assembly moves in a substantially vertical direction only and V will not, to any significant extent, be displaced horizontally.

It is preferred that the upper arms of the first and third pairs of arms are connected by a supporting brace. Similarly, it is desirable that the second and fourth pairs of arms are also connected by a supporting brace. This obviously provides the guiding assembly with greater strength and rigidity.

According to a third embodiment of this invention there is provided a rotary drive lifting assembly comprising: FIIPM ELC4\9404720.9

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a rotary drive assembly having a rotary drive unit in operational engagement with a drive shaft; lifting means adapted to raise and lower the rotary drive assembly; and a guiding assembly according to either the first or second embodiment of this invention.

The rotary drire assembly of the mixing assembly may further comprise a support frame to which the rotary drive unit is fastened. Preferably the support frame will have a substantially "LU-shaped cross-section in which case the drive unit is fastened to a substantially horizontal section of the frame. In this case, part of the drive unit may ext.;nd through a hole or cavity in the support frame in order to engage an upper end of t.ie drive shaft. The rotatable connections between the drive assembly and the substantially parallel arms of the guiding assembly may, preferably, be located on a substantially vertical section of the support frame.

The rotary drive unit may comprise a drive motor and a gear arrangement to enable the drive shaft to be rotated over a wide range of speeds.

"The lifting means of the mixing assembly may be any suitable lifting mechanism such as a hydraulic cylinder. Preferably, however, the lifting means comprises: a nut adjacent the support frame and a nut housing for inhibiting removal of the nut from the support frame; and a substantially vertical screw mounted on a base structure adapted to be received by and to co-operate with the nut, whereby rotation of the nut relative to the screw causes the support frame to move vertically with the nut. The vertical screw may extend through a hole in the support frame adjacent to which is located the nut and nut housing. The nut may be rotated by a 25 cooperating threaded worm shaft. In this case, the nut has external teeth adapted to engage and cooperate with the thread of the worm shaft.

The assembly of the third embodiment of this invention has particular application in drilling operations, fluid (or slurry) mixing operations or fluid-thickening operations.

According to a fourth embodiment of this invention there is provided a rotary drive lifting assembly comprising: a rotary drive assembly having a rotary drive unit in operational engagement with a drive cage; lifting means adapted to raise and lower the rotary drive assembly; and SIPhIELC4\94(7020.

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a guiding assembly according to the first embodiment of this invention, wherein: support structure, to which the substantially parallel arms of the guiding assembly are rotatably mounted, comprises a central column; (ii) the rotatable mounting is located adjacent the top of the central column; and (iii) the drive cage is adapted to rotate about a longitudinal axis of the central column.

The rotary drive assembly of this embodiment of the invention preferably further comprises a support frame to which the rotary drive unit is fastened. The support frame preferably has a substantially "L"-shaped cross-section, the drive unit being fastened to a substantially horizontal section of the frame. The rotatable connections between the drive assembly and the substantially parallel arms of the guiding assembly are preferably located on a substantially vertical section of the support frame.

In this fourth embodiment of the invention, the lifting means preferably comprises: 15 a nut adjacent the support frame and a nut housing for inhibiting removal of the nut from the support frame; and a substantially vertical screw, mounted on the central column, adapted to be received by and to co-operate with the nut; whereby rotation of the nut relative to the screw causes the support frame to move vertically with the nut. In all other respects, the lifting means may operate as described ,above in relation to the third embodiment of this invention.

S°The drive cage preferably comprises one or more elongated vertical legs. Although the number of such legs may vary according to the desired application, four such legs have been found to be a particularly suitable number. A rake arm may be attached to each of the vertical legs, the rake arm extending transverse to the direction of the legs in order to facilitate mixing or thickening of the liquid or slurry.

The drive unit of the rotary drive assembly preferably comprises a main gear box and a pinion gear box. The main gear box preferably has an outer rotating section which is attached to an inner stationary section of the main gear box by means of a bearing assembly. Under the action of the pinion gear box the outer rotating section of the main gear box is caused to rotate thereby rotating the drive cage.

By virtue of the simultaneous action of the pinion gear box and the lifting means, the drive cage can be rotated and vertically lifted at the same time.

FIIPMELCA447\4O2I.9 As is apparent from the above, the assembly of this fourth embodiment of the invention has particular application in fluid (or slurry) mixing operations or fluid thickening operations.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further illustrated with reference to the accompanying drawings: In the drawings, for simplicity, like components are designated with the same numeral.

Figure 1 i a side view of a guiding assembly according to a first embodiment of the invention; Figure 2 is a partial side view of the assembly of Fig. 1, illustrating a raised and a lowered (ghost lines) orientation of the assembly; Figure 3 is a plan view of the assembly of Fig. 1; 15Figure 4 is a side view of a guiding assembly according to a second embodiment of the invention; Figure 5 is a partial cross-sectional view of a separation tank with a guiding assembly according to a further embodiment of this invention located between a central column and a rotary drive assembly; Figure 6 is an enlarged partial side view of the guiding assembly of Fig. Figure 7 is a partial plan view of the guiding assembly of Fig. 6.

As illustrated in Figures 1, 2 and 3, a guiding assembly is attached to a rigid frame 1.

The guiding assembly comprises an upper pair of arms 2A, 2B (only one of the pair is shown in Figs. 1 and 2) and a lower pair of arms 3A, 3B (only one arm is shown in Figs.

1 and The upper pair of arms 2A, 2B is generally parallel to the lower pair of arms 3A, 3B.

As more clearly shown in Fig. 3, one end of each of the upper pair of arms 2A, 2B is located between and attached to a pair of lugs 12A, 12B and 12C, 12D on the frame 1, by means of connecting pins 5A, 5B respectively. Each of the lower pair of arms 3A, 3B is attached to a pair of lugs 13A, 13B and 13C, 13D on the frame 1, by means of connecting pins 6A, 6B, respectively.

Each of the pairs of arms 2A, 2B and 3A, 3B, is free to rotate about the respective connecting pins 5A, 5B and 6A, 6B.

FI IPM ELC4\94(1.7020.9 The distant ends of the arms 2A, 2B, 3A, 3B are rotatably connected to connecting arms 14A, 14B which are affixed to a moveable frame 4. One of the upper pair of arms 2A is connected to an upper portion of connecting arm 14A by pin 7A and the other arm 2B of the pair of arms 2 is connected to an upper portion of connecting arm 14B by pin 7B.

One of the lower pairs of arms 3A is connected to a lower portion of connecting arm 14A by pin 8A and the other arm 3B of the pair of arms is connected to a lower portion of connecting arm 14B by pin 8B.

Arms 2A and 2B are connected by a supporting brace 9 which ensures that arms 2A and 2B remain in parallel alignment and that the axis of rotation of pins 7A, 7B is always parallel with the axis of rotation of pins 5A, 5B. Similarly, a supporting brace 10 also connects arms 3A, 3B, Similar supporting braces (not shown) also connect arms 2A, 2B and 3A, 3B and 16A, 16B and 17A, 17B of the embodiment of the invention shown in Fig. 4. The embodiment of the invention shown in Fig. 6 also incorporates similar supporting braces (not shown) connecting arms 16A, 16B and 17A, 17B.

The moveable frame 4, which is affixed to the connecting arms 14A, 14B, has a generally "L"-shaped vertical cross-section, comprising an upright section 4A and a horizontal section 4B. The connecting arms 2A, 3A are attached to the upright section 4A. The horizontal section 4B of the moveable frame 4 has a distant end which is adapted to engage a lifting mechanism 29.

20 Another arrangement according to the invention is shown in Fig. 4. In this arrangement, the vertical guiding means comprises a first pair of vertically spaced substantially parallel arms 2A and 3A. Each of arms 2A and 3A is rotatably mounted on a first vertical support column 1A by pins 5A and 6A respectively. Pin 5A is supported by and extends between lugs 12A and 12B (lug 12B is not shown). Pin 6A is supported by and extends between lugs 13A and 13B (lug 13B is not shown). A second pair of vertically spaced substantially parallel arms 16A, 17A is rotatably mounted on a second vertical support column 1B by pins 18A. Upper pin 18A is supported by and extends between lugs 19A and 19B (lug 19B is not shown). Lower pin 18A is supported by and extends between lugs 20A and 20B (lug 20B is not shown). An upper link arm 21A connects 30 upper arms 2A and 16A of the first and second pairs of arms. A lower link arm 22A connects lower arms 3A and 17A of the first and second pairs of arms.

Link arm 21A is rotatably connected to arm 2A by means of a pin 23A and to arm 16A by means of a pin 24A. Link arm 22A is rotatably connected to arm 3A by a pin and to arm 17A by means of a pin 23A.

At a point approximately mid-way along link arm 21A is a pin 26A by which the moveable frame 4 is rotatably connected to link arm 21A. Similarly, approximately FHPMELC4194047020,9

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mid-way along link arm 22A is a pin 27A by which the moveable frame 4 is rotatably connected to link arm 22A.

In the embodiment of the invention shown in Fig. 4, as the moveable frame 4 is raised or lowered by virtue of the operation of the lifting mechanism 28, the relevant arms rotate in relation to one another and in relation to the vertical supports 1A and lB.

During such motion, pins 26A and 27A remain in substantially the same vertical line thereby causing the moveable frame 4 to move along this vertical line.

The lifting mechanism 28 is a screw jack comprising a vertical screw shaft 29 attached to a base support 11. A rotatable nut 30 is connected to the moveable frame 4 and is engaged about the vertical screw shaft 29.

Nut 30 may be rotated by any suitable means and is not shown. However, a substantially horizontal worm screw may be used as one non limiting example. In such a case, the nut 30 will include protruding teeth on its external surface. Those teeth engage the thread of the worm screw in such a way that as the worm screw rotates, the nut 30 is also rotated. The worm screw world typically be driven by an electric motor.

o• The rotation imparted to the nut 30 causes the nut to move along the vertical screw to raise or lower the moveable frame 4.

o °Mounted upon the horizontal section of moveable frame 4 is a rotary drive unit 2 including a rake drive motor 31 (partially shown in Figure 1) attached to a rake drive gear box 32 (also partially shown in Figure Extending vertically down from and in operational engagement with the motor 31 is a rake drive shaft 33 which is driven by the motor 31. Rake arms (not shown) are attached to the distant end of the drive shaft 33.

As the drive shaft 33 rotates, the rake arms also rotate.

By means of the lifting mechanism 28, the moveable frame 4 may be raised or lowered 25 thereby raising or lowering the motor 31, the gear box 32, and the drive shaft 33.

o 9 As will be appreciated, in the embodiment of the invention shown in Figs 1 to 3, the pairs of arms 2A, 2B and 3A, 3B guide the drive shaft in a substantially vertical direction whilst keeping the drive shaft in substantially vertical orientation as the drive Soshaft is raised or lowered. There is some degree of horizontal displacement of the drive shaft 33, by virtue of the arcuate movement of the moveable frame 4 as it rotates (partially) about pins 5A, 5B, 6A, 6B, which does place some strain on the drive shaft 33. Although this is generally not sufficient to have any real adverse effect upon the operation of either the lifting mechanism 28 or the operation of the rake arms, this strain is largely avoided in the assembly shown in Fig. 1 I:IIPM iLC4\94(r47020.9 I- I In the embodiment of the invention shown in Fig. 4, the rotary drive assembly (including the drive shaft 33) moves in an almost perfectly vertical orientation, with minimal horizontal (or arcuate) motion. This reduction in horizontal movement of the drive assembly reduces the lateral forces placed upon the vertical shaft, thereby reducing frictional forces applied to the lifting assembly.

The guiding assembly shown in Figs. 5, 6 and 7 is mounted upon a rigid central column 34 which is affixed to the floor of a settling tank 35. The rotary drive unit in operational engagement with a drive cage 36. The rotary drive unit comprises a main gear box 37 and a pinion gear box 38. As shown in Figure 7, a peripheral section 37A of the main gear box 37 rotates about a stationary inner section 37B of the main gear box 37 by means of a bearing assembly (not shown). The outer rotating section 37A is rotated by means of the operation of the pinion gear box 38 (not shown in Figure 7).

Attached to the outer rotating section 37A of the main gear box 37 is the drive cage 36 having vertical legs 39 extending from the peripheral section 37A of the main gear box 37. Attached to a lower section of each leg 39 is a rake arm 40 extending substantially transverse the direction of the leg 39.

a. a oi o° As shown in Fig 5, the rake arm40 has rake blades 41 extending downwardly therefrom.

°et ••As more particularly shown in Fig. 6, the column-mounted guiding assembly has a pair of vertically spaced, parallel arms 42A and 43A. One end of each arm 42A and 43A is rotatably connected to a lower "L"-shaped frame 44A. The other end of each arm 42A and 43A is rotatably connected to an upper, moveable "L"-shaped frame 44B. The rotatable connections are effected by means of pins 45A, 46A, 47A and 48A. Extending a between the substantially vertical portions of the "L"-shaped frames are the vertically spaced substantially parallel arms 42A and 43A. Preferably, there are two further such vertically spaced arms which are substantially parallel to and horizontally spaced from the vertically spaced arms which are also attached to the opposing frames 44A and 44B.

The lifting means 49 is mounted on the central column 34. An upper portion of the lifting means 49 is connected to the main gear box 37.

*se.

ii a The column-mounted guiding assembly preferably has a second pair of vertically spaced, parallel arms (not shown) which are horizontally spaced from and parallel to the first pair of parallel arms 42A and 43A.

As the lifting means 49 raises and lowers the main gear box 37 above the central column 34, the vertical legs 39 and the rake arms 40 are raised accordingly. The guiding assembly helps to reduce some of the frictional forces which would otherwise FHPIPLC4W94D4720.9

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MW71(111123 11 need to be overcome by the lifting means 49 by virtue of horizontal forces imparted to the drive cage 36 and by the rotation of the rake arm The guiding assembly of this invention enables a rotating drive shaft or a rotating drive cage to be raised out of or lowered into a fluid separation tank relatively easily owing to the lower frictional forces within the guiding means. Accordingly, less force is required to raise or lower the drive shaft or drive cage. This results in lower power requirements and enables relatively cheap lifting mechanisms to be employed.

This may be compared to vertical guiding sleeves or guide key arrangements of the prior art in which horizontal displacement of the drive shaft causes a great amount of friction io between the shaft and the sleeve or guide key arrangement. In these aspects of the prior art, large forces are required to be applied to overcome the frictional forces and to lift the shaft, As will be appreciated, this invention is not limited to the specific embodiments disclosed Sherein and may have applications in other fields, such as in the mining exploration industry.

15 It will be understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text or drawings. All of these different combinations constitute various alternative aspects of the invention.

It will also be understood that where the term "comprises" or its grammatical variants, is 20 employed herein, it is equivalent to the term "includes" and is not to be taken as excluding the presence of other elements or features.

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Claims (11)

1. 2. A guiding assembly according to claim 1 including two pairs of vertically spaced substantially parallel arms, each of said pairs of arms being horizontally spaced from and substantially parallel to the other pair of anms.
2. 3. A guiding assembly according to claim 1 or claim 2 wherein the parallel arms are rotatably mounted on the support structure at one end of each of the arms and the arms are rotatably connected to the drive assembly at the other end of each of the arms. 5 is 4. A guiding assembly according to claim 2 or claim 3 wherein each of the horizontally spaced and parallel arms are connected by a supporting brace. A guiding assembly for maintaining a rotary drive assembly in a predetermined orientation whilst raising or lowering the drive assembly, said guiding assembly o including: a first pair of vertically spaced substantially parallel arms rotatably mounted on a first support structure; a second pair of vertically spaced substantially parallel arms rotatably mounted on a second support structure opposite the first support structure; an upper link arm connecting upper arms of the first and second pairs of 25 arms, said link arm being rotatably connected to said upper arms; and a lower link arm connecting lower arms of the first and second pairs of arms, said link arm being rotatably connected to said lower arms, wherein each link arm is rotatably connected to the drive assembly at a point intermediate its ends.
3. 6. A guiding assembly according to claim 5 further including: a third pair of vertically spaced substantially parallel arms rotatably R{ g mounted on the first support structure and being horizontally spaced from and substantially parallel to the first pair of arms; ~-a~mr~arsa~ tI\%7lIjKIII2 S 13 a fourth pair of vertically spaced substantially parallel arms rotatably mounted on the second support structure and being horizontally spaced from. and substantially parallel to the second pair of arms; an upper link arm connecting upper arms of the third and fourth pairs of arms, said link ar'n being rotatably connected to said upper arms; and a lower link arm connecting lower arms of the third and fourth pairs of arms, said link arm being rotatably connected to said lower arms; wherein each link arm is rotatably connected to the drive assembly at a point intermediate its ends. :o 7. A guiding assembly according to claim 5 or claim 6 wherein the two ends of each link arm are rotatably connected to ends of respective parallel arms.
4. 8. A guiding assembly according to claim 6 or claim 7 wherein the upper arms of the o first and third pairs of arms are connected by a supporting brace and the second and ~fourth pairs of arms are also connected by a supporting brace. S.. 15 9. A rotary drive lifting assembly including: a rotary drive assembly having a rotary drive unit in operational engagement with a drive shaft; lifting means adapted to raise and lower the rotary drive assembly; and i a guiding assembly according to any one of claims i to 9. S 20 10. A rotary drive lifting assembly according to claim 9, wherein the rotary drive •"assembly further includes a support frame to which the rotary drive unit is fastened.
5. 11. A rotary drive lifting assembly according to claim 10, wherein the support frame has a substantially "L"-shaped cross-section, the drive unit being fastened to a substantially horizonta section of the frame. S@ 25 12. A rotary drive lifting assembly according to claim 10 or claim 11, wherein the rotatable connections between the drive assembly and the substantially parallel arms of the guiding assembly are located on a substantially vertical section of the support frame.
6. 13. A rotary drive lifting assembly according to any one of claims 10 to 13, wherein the lifting means includes: a nut adjacent the support frame and a nut housing for inhibiting removal of the nut from the support frame; and i 1~--18I 14 a substantially vertical screw mounted on a base structure adapted to be received by and to co-operate with the nut; whereby rotation of the nut relative to the screw causes the support frame to move vertically with the nut.
7. 14. A rotary drive lifting assembly, for mixing a liquid or slurry, including: a rotary drive assembly having a rotary drive unit in operational engagement with a drive cage; lifting means adapted to raise and lower the rotary drive assembly; and a guiding assembly according to any one of claims 1 to 4; wherein: the support structure, to which the substantially parallel arms of the guiding assembly are rotatably mounted, includes a central column; (ii) the rotatable mounting is located adjacent the top of the central column; and (iii) the drive cage is adapted to rotate about a longitudinal axis of the central column. A rotary drive lifting assembly according to claim 14, wherein the rotary drive assembly further includes a support frame to which the rotary drive unit is fastened.
8. 16. A rotary drive lifting assembly according to claim 15, wherein the support frame has a substantially "L"-shaped cross-section, the drive unit being fastened to a substantially horizontal section of the frame.
9. 17. A rotary drive lifting assembly according to claim 15 or claim 16, wherein the rotatable connections between the drive assembly and the substantially parallel arms of the guiding assembly are located on a substantially vertical section of the support frame. S
10. 18. A rotary drive lifting assembly according to any one of claims 15 to 17, wherein the lifting means includes: a nut adjacent the support frame and a nut housing for inhibiting removal of the nut from the support frame; and a substantially vertical screw, mounted on the central column, adapted to be received by and to co-operate with the nut; RV whereby rotation of the nut relative to the screw causes the support frame to ,If move vertically with the nut. I,'1?711WIl2 S
11. 19. A guiding assembly, for maintaining a rotary drive assembly in a desired orientation while raising or lowering the drive assembly, substantially as hereinbefore described with reference to any one of Figures 1 to 7. A rotary drive lifting assembly substantially as hereinbefore described with reference to any one of Figures 1 and 4 to 7. Baker Hughes Incorporated By their registered Patent Attorneys So FREEHILLS PATENT ATTORNEYS 18 April, 1997 0g *0 p 00 *8 0 *00 S 000 *0 0 0S* 0000 *0 001 0* OP rarus ABSTRACT A guiding assembly for maintaining a rotary drive assembly in a predetermined orientation whilst raising or lowering the drive assembly, said guiding assembly comprising at least one pair of vei.cally spaced substantially parallel arms rotatably mounted on a support structure and rotatably connected to the drive assembly (31). S*