GB2170166A - Portable power take-off device, particularly for extracting power from a belt conveyor; and a fines conveyor drivable by such power take-off device - Google Patents

Abstract

A portable power take-off device intended, in use, to extract power from a belt conveyor and to use such extracted power to operate secondary apparatus, comprises a drivable rotary means 9 adapted to make frictional, driving engagement with a portion 2 of a principal, belt conveyor 3, the resulting torque at the drivable rotary means 9 being employed to power the secondary apparatus 1. The portable power take-off device 8, may comprise a support frame 10 rotatably carrying at least two drivable rotary means 9, 12 having mutually spaced-apart peripheries contacting opposite sides of the belt 2, with means to adjust the relative position of at least one drivable rotary means 9 or 12 with respect to the support structure 10, and means 15, 16, 17 to transfer the resulting torque to power means to provide power to secondary apparatus 1. The secondary apparatus may be a fines conveyor 1 which may be an endless scraper chain conveyor or a pusher. <IMAGE>

Description

SPECIFICATION Portable power take-off device, particularly for extracting power from a belt conveyor; and a fines conveyor drivable by such power take-off device This invention relates to a portable power take-off device, suitable for use in extracting power from a belt conveyor to operate power-drivable secondary apparatus in circumstances or locations where a conventional source of power, such as electrical energy or hydraulic pressure fluid, is not normally available, but where a belt conveyor is in the vicinity where operation of power-drivable apparatus is required, for belt conveyors are known to extend over substantial distances, both above and below ground, being used extensively for the handling of bulk materials such as coal, iron ore, sand, clay etc.

The secondary apparatus may for instance be equipment such as a fines conveyor or a drilling machine; or tools such as a drill, a pump, bolt cutters, mine archway withdrawers etc. Another aspect of the invention also includes a fines conveyor incorporating such power take-off device.

Basically, a fines conveyor is a supplementary conveyor intended to be located beneath the discharge, head end of a principal, belt conveyor, so that fines temporarily adhering to the belt surface after the belt has been inverted into its bottom run, are deposited onto the fines conveyor, rather than the floor. Thus, a fines conveyor would be located beneath a short length length, e.g. 30ft., of the bottom run of the principal, belt conveyor.

Various forms of fines conveyors are known, requiring continuous or intermittent drive to discharge the collected fines from the fines conveyor onto a secondary conveyor. In detail, pusher drives are known whereby the fines conveyor is intermittently discharged by actuating one or more hydraulic rams to push scraper blades along a collecting surface of the fines conveyor towards a discharge end of that conveyor, while scraper chain drives are also known in which an endless chain(s) carrying a plurality of spaced apart flight or scraper bars is driven to empty the fines conveyor. it will be appreciated however, that a source of power is required to effect driving of the fines conveyor, irrespective of the construction of that conveyor.

Such power source usually comprises an electric motor and a speed reduction gearbox. It follows that an electric power supply line to the motor is also required. Furthermore, some control means e.g., a signalling/timing system of an automatic type, or alternatively a manually operated system, is also required if the fines conveyor is to be driven only when the principal conveyor is running.

Furthermore, in other underground locations, e.g.

along a roadway in which is housed a belt conveyor, it may be required to effect repair or maintenance workthatwould be assisted if a powertool could be employed, but usually no local power source is available, and the power take-off device in accordance with the invention would remedy this deficiency.

According to a first aspect of the present invention, there is provided a portable power take-off device intended, in use, to extract power from a belt conveyor and to use such extracted power to operate secondary apparatus, the device comprising a drivable rotary means adapted to make frictional, driving engagement with a portion of a principal, belt conveyor and the resulting torque at the drivable rotary means being employed to power the secondary apparatus.

According to a second aspect of the present invention, there is provided a portable power takeoff device, comprising a support frame rotatably carrying at least two drivable rotary means having mutually spaced-apart peripheries, with means to adjust the relative position of at least one drivable rotary means with respect to the support structure, the drivable rotary means being adapted, in use, to be brought into frictional drive relationship with opposite sides of the belt of a belt conveyor, and means to transfer the resulting torque to power means to provide power to secondary apparatus required to be driven.

According to a third aspect of the present invention, there is provided a fines conveyor on which is mounted a power take-off device in accordance with the first or second aspects of the invention, which device is operable to drive the fines conveyor.

Thus, the energy to power the secondary apparatus, e.g. a fines conveyor, drill, pump etc., is extracted from the principal conveyor, by means of the drivable rotary means. This provides the advantage that no separate power source/drive means and attendant control means for the secondary apparatus is required. Furthermore, if the secondary apparatus is a fines conveyor, the latter is only operable, yet automatically operable, when the principal conveyor is running.

Thus, the or each drivable rotary means is preferably a roller although an endless belt arrangement of relatively short length is possible if contact over a greater area is required.

The power may be transferred from the drivable rotary means to the secondary apparatus by any convenient direct or indirect means.

A direct, mechanical drive may be effected by a propeller shaft or a flexible cable of the Bowden type.

In a preferred arrangement, of indirect transfer, the torque extracted from the principal conveyor by the drivable rotary means is employed to drive an hydraulic pump(s) and consequently an hydraulic motor is associated with the secondary apparatus to drive the latter, with suitable hydraulic fluid lines extending between the pump and motor. Thus, with a source of pressure fluid available from the pump(s), a single secondary apparatus, or a plurality of the same or different secondary apparatuses (if located in reasonable close proximity to one another), may be powered by running suitable hosing to second or third apparatuses. In another arrangement, of indirect transfer, the torque is employed to drive an electrical generator to drive through a suitable control arrangement, electrical secondary apparatus, e.g. a lighting system, an electrically powered drill, water pump etc.

The portion of the principal belt conveyor with which the drivable rotary means makes frictional contact may be the belt proper, or a drive or return roller of the principal convveyor. If power is extracted from the belt, this is preferably from the return run which is nottroughed and consequently the drivable rotary means is able to make frictional, driving engagement with the full width of the belt return run.

With the or each drivable rotary means in the form of a drivable roller, this is preferably either of a lagged kind i.e., provided with a felt or other covering, or having an outer (plain or ribbed) surface ortyre of a material such as rubber, synthetic plastics etc., that will achieve satisfactory friction drive having regard to the material of the portion of the principal belt conveyor with which frictional contact is made, and the nature and condition of the fines. It is usually desirable to have the, one, or each drivable roller adjustable in position with respect to the engaged portion ofthe principal conveyorto enable the energy extracted from the engaged portion to be varied to suit particular operating conditions e.g., the horse power required to drive a particular secondary apparatus whether the principal conveyor is in a wet or dry condition etc.It will be appreciated that forcing the or one drivable roller against the return run of the principal conveyor deflects the latter (this can be upwardly or downwardly) and this to some extent dictates the angle of lap of the belt around the periphery of the drivable roller and consequently the horse power that may be extracted from the engaged portion of the bottom run. If the belt is wet there is an increased possibility of slippage between the belt and the driven roller, and wet conditions would frequently be encountered if coal were being conveyed (due to the use of dust suppression water sprays etc.), and/or if the principal belt conveyor were located out doors e.g. at a power station or quarry.Hence, it is preferred to provide further control of the angle of lap of the device in accordance with the first aspect of the invention by locating an upstream and a downstream jockey roller to each side of the drivable roller. This three roller arrangement consequently avoids the need to put additional loading on, and consequent displacement of, the engaged portion of the return run than would be the case without the jockey rollers. With the three roller arrangement the drivable roller may be fixed in position, if the jockey rollers are adjustable, or the jockey rollers may be fixed in position if the drivable roller is adjustable, or all three rollers may be adjustable.

It will be appreciated that if the secondary apparatus requires more power than can be extracted by a single drivable rotary means, then second orfurther such rotary means may be provided to attain the necessary power output.

With the power take-off device in accordance with the second aspect of the invention a pair of drivable rollers are adapted to be located to opposite sides of the bottom run or return run of the belt of the principal belt conveyor, with the positional adjusting means activated to provide an adequate gripping action for the power extraction requirements and/or adequate angles of lap. It will be appreciated that when the edge portion of the belt is gripped or nipped between the pair of drivable rollers, then no disadvantageous deflection of the belt occurs with this second embodiment, whilst it is of course desirable to provide adequate anchoring means for the support frame.

If a single pair of drive roller is insufficient to extract the required power from the belt, then the support structure may be provided with multiple pairs. Alternatively, or in addition, multiple numbers of support structures may be ganged together to meet the power extraction requirements.

It is desirable of course that the device in accordance with the second aspect is of compact overall length such that it may be applied without difficulty to the lower/return/bottom run of the conveyor, in the gaps conventionally present between adjacent return idlers, with the latter located at conventional spacing.

Adjustment of the position of the or each drivable roller of the device in accordance with the second aspect of the invention, with respect to the support structure, is preferably effected mechanically, e.g. by a screw arrangement. Thus, the force with which the drivable rollers grip the bottom run is adjusted by the screw arrangement. Alternatively, if more than two rollers are involve, then positional adjustment of the roller(s) varies the angle of lap irrespective of whether a gripping action is involved between adjacent roller peripheries, and hence varies the torque that can be frictionally transmitted to the rollers by the bottom run. It will be appreciated that the gripping forces and angles of lap will need to be adjusted to suit particular operating conditions, e.g.

depending on whether the material being handled by the conveyor is wet or dry. Increased torque can of course be accommodated by increasing the width of the roller, if necessary until the full width of the bottom run is engaged, in contrast to the preferably of clamping only to an edge portion of the bottom run.

With a two roller arrangement adapted to grip the bottom run, torque may be extracted at one or both rollers, and in the latter case both rollers could drive individual hydraulic pumps. However, with whatever roller system is involved, the rollers are preferably spring mounted so that the conventionally-provided fastening hooks of the belt may readily pass between the rollers.

The support frame is preferably of relatively lightweight construction to ease portability and may be provided with wheels or skids or carried by the user. The support frame may be floor-mounted and attached to the conventional belt conveyor support structure or stringers, by a torque arm. Alternatively, the support frame may be readily attachable to, and detachable from, the conveyor support structure, e.g. by screw clamps.

With the secondary apparatus in the form of a fines conveyor, this may be of a kind employing an endless circulatory conveying means and a rotary drive means for such conveying means, e.g. by being of a scraper chain kind, or of a belt kind; or alternatively may be a pusher kind.

If of the scraper chain kind, the fines conveyor may further comprise at least one endless chain, a plurality of flight bars attached, at spaced intervals, to the chain(s), a chain drive sprocket provided at one end of the fines conveyor and a chain return sprocket provided at the other end of the fines conveyor. The employment of a fines conveyor of the scraper chain type also introduces the possibility of employment of another feature, of independent significance, in accordance with which some of the scraper elements are in scraping engagement with a length of the surface of the belt of the return run of the principal belt conveyor, from which surface fines are to be detached, and are drivable by the drive means at a different speed to that of the return run thereby constituting a combined fines conveyor/belt scraper.A portion of the endless, circulatory conveying means thereof may be displaced or deflected into engagement with a corresponding portion of the return run. Alternatively, a portion of the return run may be displaced or deflected into engagement with a corresponding portion of the endless circulatory conveying means of the fines conveyor. Yet again, both portions intended to be brought into scraping relationship may be displaced or deflected into mutual engagement. The scraper elements of the fines conveyor/belt scraper may take the form of flight bars or scraper bars of a chain conveyor, the bars engaging the belt surface from which fines are to be detatched, while if such means takes the form of a belt conveyor, the latter is preferably provided with a plurality of linearly spaced apart, transversely extending, projecting ribs to engage the belt surface of the principal conveyor.

Displacement or deflection is conveniently effected by a pair of rotary members e.g., rollers or sprocket barrels spaced apart from one another by a distance dictated by the length of engagement/ scraper portion required. The rotary members are preferably adjustable in position so that the contact, scraping pressure between the abutting portions may be varied to suit particular operating conditions.

Also the rotary members may be resiliently mounted e.g., by the use of springs, rubber blocks etc.

The fines conveyor/belt scraper is preferably driven in the same direction as the bottom run of the principal conveyor, with speed differential achieved by driving the fines conveyor/belt scraper at a slower speed e.g., at 5% to 50% of the belt speed.

If of the belt kind, the fines conveyor may comprise an endless belt, a belt drive roller provided at one end of the fines conveyor and a belt return roller provided at the other end of the fines conveyor.

Intermediate, idler rollers may also be required.

If of the pusher kind, the fines conveyor may comprise a fixed position, elongate, fines-catching surface and at least one scraper bar displacable along the surface by means of at least one doubleacting, hydraulic ram, to push fines from the discharge end of the fines conveyor.

With the secondary apparatus constituted by a fines conveyor incorporating a rotary drive means in the form of a sprocket barrel or a belt drive roller, an hydraulic drive motor of the fines conveyor may be connected to the rotary drive means Such via a step up or step down gearbox. For a fines conveyor incorporating a linear drive member e.g. a hydraulic ram, the hydraulic pump is connected to the ram via suitable valving. Alternatively, in a first embodiment of direct transfer to a rotary drive means, the drivable roller may be connected mechanically to the rotatary drive means, by a propeller shaft. In a second embodiment, the mechanical connection may be a geared drive.

As a further development of the invention, the power take-off device may also be employed to drive a rotary belt wiper, intended to dislodge fines that had not fallen from the surface of a principal, belt conveyor upon that surface being inverted into the return run, but still adhering to the belt surface.

Conveniently, with the drivable rotary means constituted by a drivable roller, the torque to drive one secondary apparatus is extracted from one end of the drivable roller, while torque to drive the belt wiper is extracted from the other end of the drivable roller. The drive between the drivable roller and the belt wiper may conveniently be a geared drive, which may be of a step up or step down kind. In detail, the belt wiper conveniently has an axis of rotation parallel to that of the drivable roller. In this case, the belt wiper may be of a corkscrew kind or alternatively wire brush kind.

The invention will now be described in greater detail, by way of examples, with reference to the accompanying drawings in which: Figure 1 is a diagrammatic perspective view of a first embodiment of portable power take-off device in accordance with a first aspect of the invention, and an embodiment of fines conveyor in accordance with the second aspect of the invention; and Figure 2 is a diagrammatic side elevation of a second embodiment of portable power take-off device in accordance with a first aspect of the invention, and an embodiment of fines conveyor in accordance with the second aspect of the invention.

In both embodiments, like components are accorded like reference numerals.

In the drawings is illustrated a secondary apparatus in the form of a fines conveyor 1 located beneath a return run 2 of a principal, belt conveyor 3 at the discharge, head end thereof, where conveying run 4 of the belt conveyor 3 passes round a return roll 5 into the bottom run 2, material such as coal, iron ore, sand etc., being discharged from the conveying run 4 at the head end onto a receiving conveyor 7, e.g. of the belt type, located slightly beyond, and beneath, the head end of the belt conveyor 3.

In the embodiment of Figure 1, a portable power take-off device 8 is shown mounted on the fines conveyor 1, the power take-off device 8 comprising a drivable roller 9 rotatably supported on a pair of support arms 10 bolted to the fines conveyor 1, for rotatation of the roller 9 about an axis 11, parallel to the axis 6, the periphery of the drivable roller 9 making frictional, driving engagement with a portion of the adjacent surface of the return run 2. Upstream and downstream of the roller 9 are a pair of jockey rollers 12 rotatable about axes 13 parallel to the axis 6, the jockey rollers 12 being adjustable in position as indicated by the arrows 14 so that the angle of lap of the return run 2 about the periphery of the drivable roller 9 may be varied to suit particular operating conditions.

The embodiment of fines conveyor 1 illustrated in Figure 1 is also of a direct drive kind, in that the drivable roller 9 is connected to a first bevel gearbox (not shown) with a vertical output shaft 15 of this gearbox extending to a second bevel gearbox 16, with a horizontal output shaft 17 thereof extending to a third bevel gearbox (not shown), an output shaft of which drives a drive sprocket barrel 18 of the fines conveyor 1, the latter being of the scraper chain type, comprising a plurality of transverse scraper bars 19 connected at their outer ends to a pair of spacedapart, endless, round link chains 20 passing around sprockets 21 of the drive sprocket barrel 18 and sprockets 22 of a return sprocket barrel 23. The sprocket barrels 18 and 23 are rotatably supported across parellel side walls 24 of a rigid, rectanguiar structure 25 which includes a deck plate 26 to separate the upper, conveying run 27 from a lower, return run 28.

In the embodiment of Figure 2 the fines conveyor 1 is also of the scraper chain type, but apart from collecting fines, is additionally employed as a scraperfor the return run 2. Thus, beyond the second jockey pulley 12 is located a pulley 29 to define a horizontal section 30 of the return run 2, while a horizontal section 31 of the chains 20, and consequentlyflight bars 19 is elevated into scraping engagement with the horizontal section 30 by means of additional, non-driven sprocket barrels 32, 33 spaced apart by the length of the horizontal section 31 and further non-driven sprocket barrels 34 for chain guidance/tensioning purposes.

Claims (57)

1. A portable powertake-off device intended, in use, to extract power from a belt conveyor and to use such extracted power to operate secondary apparatus, the device comprising a drivable rotary means adapted to make frictional, driving engagement with a portion of a principal, belt conveyor and the resulting torque at the drivable rotary means being employed to power the secondary apparatus.

2. A portable powertake-off device, comprising a support frame rotatably carrying at least two drivable rotary means having mutually spaced-apart peripheries, with means to adjust the relative position of at least one drivable rotary means with respect to the support structure, the drivable rotary means being adapted, in use, to be brought into frictional drive relationship with opposite sides of the belt of a belt conveyor, and means to transfer the resulting torque to power means to provide power to secondary apparatus required to be driven.

3. A power take-off device as claimed in Claim 1 or Claims 2, wherein the drivable rotary means is a roller.

4. A power take-off device as claimed in Claim 1 or Claim 2, wherein the drivable rotary means is an endless belt arrangement, of relatively short length.

5. A power take-off device as claimed in any preceding Claim, wherein the power is transferred from the drivable rotary means to the secondary apparatus by direct means.

6. A power take-off device as claimed in any one of Claims 1 to 4, wherein the power is transferred from the drivable rotary means to the secondary apparatus by indirect means.

7. A power take-off device as claimed in Claim 6, wherein the torque extracted from the principal conveyor by the drivable rotary means is employed to drive an hydraulic pump(s) and consequently an hydraulic motor is associated with the secondary apparatus to drive the latter, with suitable hydraulic fluid iines extending between the pump and motor.

8. A power take-off device as claimed in Claim 6, wherein the torque is employed to drive an electrical generatorto drive through a suitable control arrangement, electrical secondary apparatus.

9. A power take-off device as claimed in any preceding Claim, wherein the portion of the principal belt conveyor with which the drivable rotary means makes frictional contact is the belt proper.

10. A power take-off device as claimed in any one of Claims 1 to 8, wherein the portion of the principal belt conveyor with which the drivable rotary means makes frictional contact is a drive or return roller.

11. A power take-off device as claimed in Claim 3, and any Claim appendant thereto, wherein the drivable roller is of a lagged kind.

12. A power take-off device as claimed in Claim 3, and any one of Claims 5 to 10, wherein the or each drivable roller has an outer surface of rubber or synthetic plastics material.

13. A power take-off device as claimed in Claim 12, wherein the outer surface of the or each drivable roller is plain.

14. A power take-off as claimed in Claim 12, wherein the outer surface of the or each drivable roller is ribbed.

15. A power take-off device as claimed in any preceding Claim, wherein the, one, or each drivable roller is adjustable in position with respect to the engaged portion of the principal conveyor.

16. A power take-off device as claimed in Claim 15, comprising an upstream and a downstream jockey roller located on to each side of the drivable roller, the roller being rotatable about parallel axes.

17. A power take-off device as claimed in Claim 16, wherein the drivable roller(s) is adjustable in position with respect to the jockey rollers.

18. A power take-off device as claimed in Claim 16 or Claim 17, wherein the jockey rollers are adjustable in position with respect to the drivable roller.

19, A power take-off device as claimed in any preceding Claim, comprising a plurality of drivable rotary means.

20. A power take-off device as claimed in Claim 5, and any Claim appendant thereto, wherein the drivable rotary means is connected mechanically to the rotary drive means by a propeller shaft.

21. A power take-off device as claimed in Claim 5, and any one of Claims 9 to 19, wherein the drivable rotary means is connected by a gear drive to the rotary drive means.

22. A power take-off device as claimed in Claim 5, and any one of Claims 9 to 19, wherein the drivable rotary means is connected by a flexible cable to the rotary drive means.

23. A power take-off device as claimed in any preceding Claim, wherein the drivable rotary means is also employed to drive a rotary belt wiper.

24. A power take-off device as claimed in Claim 17, comprising a geared drive between the drivable rotary means and the rotary belt wiper.

25. A power take-off device as claimed in Claim 24, wherein the geared drive is of the step-up or step-down kind.

26. A power take-off device as claimed in any one of Claims 23 to 25, wherein the belt wiper has an axis of rotation parallel to that of the drivable rotary means.

27. A power take-off device as claimed in any one of Claims 23 to 26, wherein the belt wiper is of the corkscrew kind.

28. A power take-off device as claimed in any one of Claims 23 to 26, wherein the belt wiper is of the wire brush kind.

29. Afines conveyor on which is mounted a power take-off device in accordance with any pre ceding Claim, which device is operable to drive the fines conveyor.

30. Afines conveyor as claimed in Claim 29, wherein the portion of the principal belt conveyor with which the drivable rotary means makes friction al contact is the return run of the principal conveyor.

31. A fines conveyor as claimed in Claim 29, wherein the portion of the principal belt conveyor with which the drivable rotary means makes frictional contact is a drive or return roller of the principal conveyor.

32. Afines conveyor as claimed in any one of Claims 29 to 31, of a kind employing an endless circulatory conveying means.

33. Afines conveyor as claimed in Claim 32, wherein the conveying means is a scraper chain.

34. A fines conveyor as claimed in Claim 32, wherein the conveying means is a belt.

35. Afines conveyor as claimed in Claim 32, having a conveying means in the form of a pusher.

36. Afines conveyor as claimed in Claim 33, comprising at least one endless chain, a plurality of flight bars attached, at spaced intervals, to the chain(s) a chain drive sprocket provided at one end of the fines conveyor and a chain return sprocket provided at the other end of the fines conveyor.

37. A fines conveyor as claimed in Claim 36, wherein the scraper elements are drivable by the drive means at a different speed to that of the return run of a principal, belt conveyor, with a portion of the endless, circulatory conveying means of the fines conveyor in scraping relationship with a portion of the surface of the belt of the return run from which surface fines are to be detached.

38. A fines conveyor as claimed in Claim 37, when appendant to Claim 32, wherein a portion of the endless, circulatory conveying means thereof is displaced or deflected into engagement with a corresponding portion of the return run.

39. A fines conveyor as claimed in Claim 37, when appendant to Claim 32, wherein a portion of the return run of the principal conveyor is displaced or deflected into engagement with a corresponding portion of the endless circulatory conveying means of the fines conveyor.

40. Afines conveyor as claimed in Claim 37, when appendantto Claim 32, wherein both portions intended to be brought into scraping relationship are displaced or deflected into mutual engagement.

41. A fines conveyor as claimed in Claim 33, and any Claim appendant thereto, wherein the scraper elements of the fines conveyor take the form of flight bars or scraper bars of a chain conveyor, the bars engaging the belt surface from which fines are to be detached.

42. A fines conveyor as claimed in Claim 34, and any one Claim appendant thereto, wherein the scraper elements of the fines conveyor take the form of a plurality of linearly spaced apart, transversely extending, projecting ribs provided on the belt of the fines conveyor, to engage the belt surface of the principal conveyor.

43. Afines conveyor as claimed in any one of Claims 38 to 42, wherein displacement or deflection is effected by a pair of rotary members.

44. A fines conveyor as claimed in Claim 43, when appendantto Claim 33, wherein the rotary members are sprocket barrels.

45. A fines conveyor as claimed in Claim 43, when appendant to Claim 34, wherein the rotary members are rollers.

46. A fines conveyor as claimed in any one of Claims 43 to 45, wherein the rotary members are adjustable in position so that the contact, scraping pressure between the abutting portions may be varied to suit particular operating conditions.

47. A fines conveyor as claimed in any one of Claims 43 to 46, wherein the rotary members are resiliently mounted.

48. Afines conveyor as claimed in Claim 47, wherein resilient mounting is effected by springs.

49. Afines conveyor as claimed in Claim 47, wherein resilient mounting is effected by rubber blocks.

50. Afines conveyor as claimed in any one of Claims 37 to 49, driven in the same direction as the bottom run of the principal conveyor, with speed differential achieved by driving the fines conveyor/ belt scraper at a slower speed.

51. Afines conveyor as claimed in Claim 50, wherein the slower speed is 5% to 50% of the belt speed of the principal conveyor.

52. A fines conveyor as claimed in Claim 34, wherein a belt drive roller is provided at one end of the fines conveyor and a belt return roller provided at the other end of the fines conveyor.

53. A fines conveyor as claimed in Claim 52, wherein intermediate, idler rollers are provided between the drive roller and the return rollers.

54. A fines conveyor as claimed in Claim 35, comprising a fixed position, elongate, fines-catching surface and at least one scraper displaceable along the surface by means of at least one double-acting, hydraulic ram, to push fines from the discharge end of the fines conveyor.

55. Afines conveyor as claimed in Claim 35, comprising displacement means for the pusher in the form of a hydraulic ram, with an hydraulic pump of the rotary drive means connected to the ram via suitable valving.

56. A power take-off device, substantially as hereinbefore described with reference to the accompanying drawings.

57. A fines conveyor substantially as hereinbefore described with reference to the accompanying drawings.