AU2009281741A1 - Drill head and apparatus therefor - Google Patents

Description

WO 2010/019972 PCT/ZA2009/000074 -1 DRILL HEAD AND APPARATUS THEREFOR BACKGROUND OF THE INVENTION THIS invention relates to a drill head. More specifically, the invention relates to a wet drill head used for drilling applications in the mining industry. Even more specifically, the invention relates to a drill head which is convertible between a wet and dry drill head. Wet drill heads as depicted in figure 1 and figure 2 of the accompanying illustrations are generally known. Typically, the drill heads are part of a drill head assembly 200 comprising a drill head 210, a hydraulic motor 220 and an adapter plate 230 for connecting the drill head to the motor. For use, the drill head assembly 200 is mounted on a mounting bracket 240 to enable attachment thereof to a drilling rig for underground drilling, particularly for roof bolting and sidewall bolting applications. Existing wet drill heads comprise a housing 250, a shaft 260 rotatably mounted on a pair of taper roller bearings 270, 272 within the housing 250 and shaft seals 274, 276 on either end of the housing 250 to prevent the ingress of dirt into the housing and into the bearings 270, 272. The shaft 260 is typically adapted to engage the motor at one end and to receive a drill rod at an opposite end. Generally, the shaft 260 further defines a channel (not shown) extending between an inlet aperture, defined on a radial outer surface of the shaft, and the drill rod receiving end, through which water can flow. The water flowing though the channel serves two purposes, namely cooling the shaft and supplying water to the drilling surface to flush away drilling debris.

WO 2010/019972 PCT/ZA2009/000074 -2 A water chamber 278, located between the bearings 270, 272, is defined between the housing 250 and a pair of high pressure seals 280, 282 which prevent water entering the water chamber 278 through inlet port 284 from impinging on the bearings 270, 272. The inlet aperture (not shown) of the shaft 260 is located within the water chamber 278 such that pressurised water entering the water chamber 278 can be communicated into the inlet aperture, through the channel and out of the drill rod receiving end of the shaft 260. A disadvantage of the existing drill heads is that failure of the high pressure seals 280, 282 causes the water in the water chamber 278 to flow into the housing 250 thereby contaminating the grease in the housing 250 and causing premature failure of the bearings 270, 272. Without any visual indication that the seals 280, 282 have failed, the drill head assembly 200 is operated until the bearings 270, 272 are damaged and/or seize. At this point, drilling operations must be suspended to disassemble the drill head assembly 200 so as to replace the drill head 210. Often, replacement drill heads are not available on site and accordingly, drilling can only resume once a new or refurbished drill head is sourced, causing substantial down time and massive financial losses to the mine. It is an object of the present invention to provide a wet drill head that addresses the abovementioned disadvantages. SUMMARY OF THE INVENTION According to the invention there is provided a drill head including: a shaft comprising a drive means engagement end and a drill rod receiving end, the shaft further defining an inlet aperture, an outlet aperture and a channel extending between the inlet and outlet apertures; a shaft housing for housing at least a portion of the shaft; a fluid chamber for receiving a fluid, the fluid chamber being in fluid communication with the portion of the shaft defining the inlet aperture; WO 2010/019972 PCT/ZA2009/000074 -3 means for rotatably mounting the shaft within the shaft housing; one or more internal seals for preventing the ingress of fluid from the fluid chamber into the portion of the shaft housing in which the mounting means are located; and at least one fluid exhaust passageway for, in the event of the one or more internal seals failing, exhausting the fluid from the fluid chamber; such that in the event of the one or more internal seals failing, the fluid in the fluid chamber is exhausted therefrom via the fluid exhaust passageway thereby providing a visual indication of the failure of the one or more internal seals. The shaft may be a stepped shaft comprising a plurality of diametrically different sized sections, some of which having radially outer surfaces sized for receiving the radially inner surfaces of the mounting means and/or the seals. Typically, the shaft defines the inlet aperture on the radial outer surface of at least one of its sections and the outlet aperture near the drill rod receiving end thereof. Generally, the drill rod receiving end of the shaft defines an axial bore sized and shaped to receive the drill rod therein, the outlet aperture terminating in the axial bore thereby communicating fluid entering the inlet aperture and through the channel into the axial bore. The axial bore may have any cross-sectional shape for receiving interchangeable adaptors for holding various attachments. The shaft defined channel may be made up of a plurality of communicating channel bores plugged at specific locations by one or more plugs so as to direct fluid entering the inlet aperture to and out of the outlet aperture. Typically, the plurality of channel bores are, in relation to the shaft, two axial channel bores and two tangentially perpendicular channel bores in fluid communication with one another. The shaft may further define a dry drilling channel bore, extending between the axial bore defined at the drill rod receiving end of the shaft and a secondary axial bore defined at the engagement end of the shaft, the dry drilling channel bore being pluggable for wet drilling applications and opened for dry drilling applications so as to allow debris from dry drilling to WO 2010/019972 PCT/ZA2009/000074 -4 pass there through, thereby enabling the drill head to be convertible between a wet and dry drill head. Typically, the dry drilling channel bore is at least one of the channel bores defining the channel through which pressurised fluid is introducible to the fluid chamber. Preferably, a means of suction pulls the debris generated during dry drilling through the dry drilling channel bore, through a hollow drive shaft of the drive means coupled to the engagement end of the shaft and towards the suction means where the debris is collected or discarded. Preferably, the shaft housing comprises a first end beyond which the engagement end of the shaft extends, a second end beyond which the drill rod receiving end of the shaft extends and further defines a shaft housing cavity having diametrically different sized sections, some of which having radially inner surfaces sized for receiving the radially outer surfaces of the mounting means and/or seals, and/or for accommodating corresponding sections of the shaft. More preferably, the out side of the shaft housing is cylindrically shaped. The drill head may include a flinger, having an outer periphery greater than the out side periphery of one of the ends of the shaft housing, preferably the second end, so as to during use, deflect debris away from the shaft housing. Preferably, the flinger is substantially disc shaped. Typically, the mounting means is at least first and second bushes or bearings on which the shaft is rotatably supported in the shaft housing, the first bush or bearing being located nearer the first end of the shaft housing and the second bush or bearing being located nearer the second end of the shaft housing. Preferably, the bearings are taper roller bearings. The fluid chamber is preferably positioned between the first end of the shaft housing and the first bush or bearing, or between the second end of the shaft housing and the second bush or bearing, but not between the first and second bushes or bearings. In one embodiment, the fluid chamber may be defined by and integral with the shaft housing. In an alternative embodiment, the fluid chamber may be defined by a fluid chamber housing being releasably attachable to the shaft housing so as to enable easy replacement of the fluid chamber housing and/or seals therein without having to disassemble the shaft housing. Generally, the shaft housing or fluid chamber housing define a fluid chamber inlet for WO 2010/019972 PCT/ZA2009/000074 -5 introducing pressurised fluid into the fluid chamber. Typically, the fluid exhaust passageway is an exhaust channel extending between an exhaust inlet aperture and an exhaust outlet aperture, the exhaust inlet aperture being defined by an inner surface of the shaft housing, the fluid chamber housing or the shaft housing and fluid chamber housing jointly and the exhaust outlet aperture being defined by the out side surface of the shaft housing, the fluid chamber housing or the shaft housing and fluid chamber housing jointly. Alternatively, the fluid exhaust passageway may be an exhaust gap defined between contact surfaces of attached shaft and the fluid chamber housings. Preferably, the out side of the fluid chamber housing is cylindrically shaped. The one or more internal seals may be at least one first seal and at least one second seal, the first seal for preventing water and/or debris from contacting the mounting means and being located nearer the second bush or bearing than the second seal, and the second seal for sealing one end of the fluid chamber and being located nearer the fluid chamber than the first seal, such that the exhaust inlet aperture of the exhaust channel or the exhaust gap is located between the first and second seals. Preferably, the drill head further comprises at least one third seal and at least one fourth seal, the third seal for preventing water and/or debris from contacting the mounting means and being located nearer the first end of the shaft housing than any of the other seals, and the fourth seal for sealing the end of the fluid chamber opposite the end at which the second seal is located. More preferably, any one or more of the at least one first, second, third and fourth seals are a pair of first, second, third and fourth seals, the respective pair of seals being spaced apart from one another to define a lubrication chamber for receiving a lubricant therein. Most preferably, the lubricant is a grease or oil lubricant. The drill head may include a means for driving the shaft of the drill head. Preferably, the drive means is an electric, pneumatic, hydraulic or any other type of drive motor. More preferably, the drill head further includes an adaptor plate for releasably coupling the drill head to the drive means. Most preferably, the drill head further includes a means for mounting the drill head and drive means to a drilling rig. Even more preferably, the mounting means is a mounting bracket. According to a second aspect of the invention, there is provided a fluid chamber housing, WO 2010/019972 PCT/ZA2009/000074 -6 defining an inner cavity for housing that section of a drill head shaft defining a fluid inlet aperture including: seal receiving formations at or near each end of the fluid chamber housing, wherein co operation between the inner side of the fluid chamber housing and seals received in the seal receiving formations define a fluid chamber; a fluid chamber inlet for introducing fluid into the fluid chamber; and means for releasably attaching the fluid chamber housing to the drill head. The fluid chamber housing may be attachable to the drill head with a plurality of bolts, studs and/or nuts. Generally, a fluid exhaust passageway is defined by the fluid chamber housing, the drill head or the fluid chamber housing and drill head jointly so as to, in the event of seal failure, exhausting fluid therefrom thereby providing a visual indication of seal failure. BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a sectioned side view of an existing drill head assembly currently available in the art; Figure 2 shows an isometric view of the existing drill head assembly of figure 1; Figure 3 shows a sectioned side view of the drill head and fluid chamber housing combination in accordance with the present invention; Figure 4 shows a sectioned side view of the drill head assembly in accordance with the present invention; and Figure 5 shows an isometric view of the drill head assembly of figure 4.

WO 2010/019972 PCT/ZA2009/000074 -7 DETAILED DESCRIPTION OF THE DRAWINGS A drill head according to a preferred embodiment of the invention is designated generally with reference numeral 10 in figure 3. The drill head 10 comprises a shaft housing 12, a fluid chamber housing 14 and a shaft 16 passing through the shaft housing 12 and the fluid chamber housing 14. The shaft housing 12 has a cylindrical out side surface 18 and an inner stepper surface 20 defining a cavity having diametrically different sized sections for receiving mounting means 26, 28, seals 22, 24 and at least a portion of the shaft 16. The seals 22, 24 are low, normal or high pressure seals, or any combination of the aforementioned, and prevent dirt, debris and/or water from entering that portion of the shaft housing in which the mounting means 26, 28 are housed so as to inhibit damaging or seizing the mounting means 26, 28. Typically, the mounting means are bearings 26, 28, preferably taper roller bearings. The fluid chamber housing 14 also has a cylindrical an out side surface 30 and an inner surface 32 defining a cavity having diametrically different sized sections for receiving seals 34, 36 and at least a portion of the shaft 16. Although the seals 34, 36 may be low, normal or high pressure seals, or any combination of the aforementioned, it is preferable that the seals 34, 36 are high pressure seals. Although not shown in the illustrations, any one or more of the seals 22, 24, 34, 36 may be a pair of seals, the respective pair of seals being spaced apart from one another to define a lubrication chamber for receiving a grease, oil or other type of lubricant therein. Once assembled, a fluid chamber 37 is defined between the seals 34, 36, the inner surface 32 of the fluid chamber housing 14 and the shaft 16. Fluid, preferably pressurized water, is deliverable into the fluid chamber 37 via an inlet port 38. Further, the fluid chamber housing 14 is releasbaly attachable to the shaft housing 12 so as to enable replacement of the seals 34, 36 sealing the fluid chamber 37 without having to dismantle the shaft housing 12 as is the case with existing wet type drill heads. The shaft 16 is a stepped shaft having a plurality of diametrically different sized sections for receiving the mounting means 26, 28 and the seals 22, 24, 34, 36 thereon. With reference also to figure 4, the shaft 16 further comprises an engagement end 16A and a drill rod receiving end 16B. The engagement end 16A of the shaft 16 defines an axial bore 40 and keyway 42 for WO 2010/019972 PCT/ZA2009/000074 -8 securely receiving a corresponding drive shaft 44 and key 46 from a drive means 48. Although the drive means 48 could be a hydraulic, pneumatic or electric motor, it is preferable that the drive means 48 is a hydraulic motor. The drill rod receiving end 16B of the shaft 16 also defines an axial bore 50 sized and shaped to securely receive the receiving end of a drill rod (not shown). Preferably, the cross sectional shape of the axial bore 50 is hexagonal, but may be any other shape for receiving interchangeable adaptors for holding various attachments. The shaft 16 further defines an inlet aperture 52, and outlet aperture 54 and a channel 56 extending between the inlet aperture 52 and outlet aperture 54. The inlet aperture 52 is defined on a radially outer surface of the shaft 16 and the outlet aperture 54 is defined at the blind end of the axial bore 50. Preferably, the channel 56 is made up of, in relation to the shaft 16, at least two axial channel bores and two tangentially perpendicular channel bores plugged at specific locations by plugs 58, 60 so as to ensure that water entering the inlet aperture 52 passes through the channel 56 and out of the outlet aperture 54. Although not shown, the shaft may further define a dry drilling channel bore (not shown), extending between the axial bore 50 defined at the drill rod receiving end 16B of the shaft 16 and the axial bore 40 defined at the engagement end 16A of the shaft 16, the dry drilling channel bore being pluggable for wet drilling applications and opened for dry drilling applications so as to allow debris from dry drilling to pass there through, thereby enabling the drill head to be convertible between a wet and dry drill head. Preferably, the dry drilling channel bore is the axial channel bore having the outlet aperture 54 located thereon, but extended all the way through to the axial bore 40 defined at the engagement end 16A of the shaft 16 so as to place the axial bore 40 in fluid communication with the axial bore 50 defined at the drill rod receiving end 16B of the shaft 16. The dry drilling channel bore, being an extended version of the aforementioned axial channel bore, is pluggable between axial bores 40, 50 for wet drilling applications and opened for dry drilling applications. Further, a means of suction (not shown) may be used to pull the debris generated during dry drilling through the dry drilling channel bore, through a hollow drive shaft of a dry drilling drive means (not shown) coupled to the engagement end of the shaft and towards the suction means where the debris may be collected or discarded.

WO 2010/019972 PCT/ZA2009/000074 -9 Assembly of the drill head 10 generally starts with positioning of bearing 28 onto the shaft 16. The shaft 16 is then fitted through the end of the shaft housing 16 to which the fluid chamber will be connected such that the outer surface of the bearing 28 engages with the relevant stepped inner surface 20 of the shaft housing 12. In this position, the engagement end 16A of the shaft 16 extends beyond the end of the shaft housing 12. Bearing 26 is then pushed over the engagement end 16A of the shaft 16 and into position such that the outer surface of the bearing 26 engages with the relevant stepped inner surface 20 of the shaft housing 12. With the bearings 26, 28 and shaft 16 in place, the shaft 16 is rotatably mounted in the shaft housing 12. Thereafter, the seals 22, 24 are fitted into the relevant stepped sections of the shaft housing 12 so as to seal off the portion of the shaft housing 12 housing the bearings 26, 28. In this manner the. seals 22, 24 prevent the ingress of grit, dirt and /or water into the housing thereby preventing damage to the bearings 26, 28. The fluid chamber housing 14 is then assembled. High pressure seals 34, 36 are fitted into position at either end of the fluid chamber housing such that the outer surfaces of the high pressure seals 34, 36 engage with the inner surface 32 of the fluid chamber housing 14. The assembled fluid chamber housing 14 is then pushed over the drill rod receiving end 16B of the shaft 16 and into contact with the shaft housing 12. Generally, the fluid chamber housing 14 is attached to the shaft housing 12 with bolts (not shown) passing through apertures (not shown) in the fluid chamber housing 14 and into threaded engagement with threaded apertures (not shown) in the shaft housing 12. Alternatively, the fluid chamber housing 14 is attached to the shaft housing 12 with threaded studs (not shown) extending from the shaft housing 12 and through apertures (not shown) in the fluid chamber housing 14 and into threaded engagement with nuts (not shown) tightened on the end of the fluid chamber housing 14 opposite to the end in contact with the shaft housing 12. In this position, the inlet aperture 52 defined in the shaft 16 is located in the fluid chamber 37. The contact surfaces of the attached shaft housing 12 and fluid chamber housing 14 are generally not water tight thereby defining a fluid exhaust passageway in the form of an exhaust gap 62. Alternatively, the fluid exhaust passageway is an exhaust channel (not shown) extending between an exhaust inlet aperture (not shown) and an exhaust outlet aperture (not WO 2010/019972 PCT/ZA2009/000074 -10 shown), where the exhaust inlet and outlet apertures are respectively defined on the inner surface and out side surface of the shaft housing 12, the fluid chamber housing 14 or the shaft housing 12 and fluid chamber housing 14 jointly. The exhaust gap 62, or the exhaust inlet aperture of the alternative embodiment, is located between seal 24 and seal 34 so that in the event of seal 34 failing, water from the fluid chamber 37 is exhaustible through exhaust gap 62 thereby providing a visual indication of seal failure, and further minimizing the likelihood of the bearings 22, 24 from being contacted with the water due to the water taking the path of least resistance, that is through the exhaust gap 62. Referring now specifically to figure 4 and figure 5, an adaptor plate 64 is connected to the end of the shaft housing 12 beyond which the engagement end 16A of the shaft 16 extends. The drive means 48 is then connected to the adaptor plate 64 such that the drive shaft 44 and key 46 are securely received within the axial bore 40 and keyway 42 defined by the engagement end 16A of the shaft 16. The drive means 48, adaptor plate 64, drill head 12 and fluid chamber housing 14 are then fixed to a mounting bracket so as to enable the entire assembly to be mounted to a drill rig for drilling operations, particularly for rock bolt and side wall bolt drilling operations in the mining industry. In use, high pressure fluid such as water is delivered into the fluid chamber 37 via the inlet port 38 defined in the fluid chamber housing 14. Water from the fluid chamber 37 is communicated into the inlet aperture 52, through the channel 56 and into the axial bore 50 defined in the drill rod receiving end 16B of the shaft 16 via the outlet aperture 54. The water serves two purposes, namely to provide a cooling effect to the shaft 16 and to wash away and clear debris at the drilling surface. In the event of either of high pressure seals 34, 36 failing, water may be exhausted from the fluid chamber 37 via damaged seal 36 or through damaged seal 34 which in turn causes the water to be exhausted through the exhaust gap 62. This provides an operator with a visual indication of failure of internal seal 34. Having moved the fluid chamber 37 to a position not between the mounting means 26, 28 enables quick repair or replacement of seals 34, 36 and prevents a damaged drill head from being operated to the point of damaging or seizing the WO 2010/019972 PCT/ZA2009/000074 -11 mounting means 26, 28. Accordingly, reduced downtimes for repair lead to reduced financial losses associated with drilling operations. Although the invention has been described above with reference to a preferred embodiment, it will be appreciated that many modifications or variations of the invention are possible without departing from the spirit or scope of the invention. For example, the fluid chamber 37 could be integral with the shaft housing and preferably located at a position not between the mounting means and on an end of the shaft housing opposite the end to which the drive means is attachable.

Claims (37)

1. A drill head including: a shaft comprising a drive means engagement end and a drill rod receiving end, the shaft further defining an inlet aperture, an outlet aperture and a channel extending between the inlet and outlet apertures; a shaft housing for housing at least a portion of the shaft; a fluid chamber for receiving a fluid, the fluid chamber being in fluid communication with the portion of the shaft defining the inlet aperture; means for rotatably mounting the shaft within the shaft housing; one or more internal seals for preventing the ingress of fluid from the fluid chamber into the portion of the shaft housing in which the mounting means are located; and at least one fluid exhaust passageway for, in the event of the one or more internal seals failing, exhausting the fluid from the fluid chamber; such that in the event of the one or more internal seals failing, the fluid in the fluid chamber is exhausted therefrom via the fluid exhaust passageway thereby providing a visual indication of the failure of the one or more internal seals.

2. A drill head according to claim 1, wherein the shaft is a stepped shaft comprising a plurality of diametrically different sized sections, some of which having radially outer surfaces sized for receiving the radially inner surfaces of the mounting means and/or the seals.

3. A drill head according to claim 2, wherein the shaft defines the inlet aperture on the radial outer surface of at least one of its sections and the outlet aperture near the drill rod receiving end thereof.

4. A drill head according to claim 1, claim 2 or claim 3, wherein the drill rod receiving end of the WO 2010/019972 PCT/ZA2009/000074 -13 shaft defines an axial bore sized and shaped to receive the drill rod therein, the outlet aperture terminating in the axial bore thereby communicating fluid entering the inlet aperture and through the channel into the axial bore.

5. A drill head according to claim 4, wherein the axial bore has any cross-sectional shape for receiving interchangeable adaptors for holding various attachments.

6. A drill head according to any one of the preceding claims, wherein the shaft defined channel is made up of a plurality of communicating channel bores plugged at specific locations by one or more plugs so as to direct fluid entering the inlet aperture to and out of the outlet aperture.

7. A drill head according to claim 6, wherein the plurality of channel bores are, in relation to the shaft, two axial channel bores and two tangentially perpendicular channel bores in fluid communication with one another.

8. A drill head according to claim 6, wherein the shaft further defines a dry drilling channel bore, extending between the axial bore defined at the drill rod receiving end of the shaft and a secondary axial bore defined at the engagement end of the shaft, the dry drilling channel bore being pluggable for wet drilling applications and opened for dry drilling applications so as to allow debris from dry drilling to pass there through, thereby enabling the drill head to be convertible between a wet and dry drill head.

9. A drill head according to claim 7, wherein the dry drilling channel bore is at least one of the channel bores defining the channel through which pressurised fluid is introducible to the fluid chamber.

10. A drill head according to claim 6 or claim 7, wherein a means of suction pulls the debris generated during dry drilling through the dry drilling channel bore, through a hollow drive shaft of a dry drilling drive means coupled to the engagement end of the shaft and towards the suction means where the debris is collected or discarded.

11. A drill head according to any one of the preceding claims, wherein the shaft housing comprises a first end beyond which the engagement end of the shaft extends, a second end WO 2010/019972 PCT/ZA2009/000074 -14 beyond which the drill rod receiving end of the shaft extends and further defines a shaft housing cavity having diametrically different sized sections, some of which having radially inner surfaces sized for receiving the radially outer surfaces of the mounting means and/or seals, and/or for accommodating corresponding sections of the shaft.

12. A drill head according to any one of the preceding claims, wherein the out side of the shaft housing is cylindrically shaped.

13. A drill head according to any one of the preceding claims, wherein the drill head includes a flinger, having an outer periphery greater than the out side periphery of the end near which it is attachable, for during use, deflecting debris away from the shaft housing.

14. A drill head according to claim 13, wherein the flinger is substantially disc shaped.

15. A drill head according to any one of the preceding claims, wherein the mounting means is at least first and second bushes or bearings on which the shaft is rotatably supported in the shaft housing, the first bush or bearing being located nearer the first end of the shaft housing and the second bush or bearing being located nearer the second end of the shaft housing.

16. A drill head according to claim 15, wherein the bearings are taper roller bearings.

17. A drill head according to claim 15 or claim 16, wherein the fluid chamber is positioned between the first end of the shaft housing and the first bush or bearing, or between the second end of the shaft housing and the second bush or bearing, but not between the first and second bushes or bearings.

18. A drill head according to any one of the preceding claims, wherein the fluid chamber is defined by and integral with the shaft housing, the portion of the shaft housing defining the fluid chamber further defines a fluid chamber inlet for introducing pressurised fluid into the fluid chamber.

19. A drill head according to any one claims 1 to 17 wherein the fluid chamber is defined by a fluid chamber housing, the fluid chamber housing being releasably attachable to the shaft WO 2010/019972 PCT/ZA2009/000074 -15 housing so as to enable easy replacement of the fluid chamber housing and/or seals therein without having to disassemble the shaft housing.

20. A drill head according to claim 19, wherein the fluid chamber housing defines a fluid chamber inlet for introducing pressurised fluid into the fluid chamber.

21. A drill head according to claim 18, claim 19 or claim 20, wherein the fluid exhaust passageway is an exhaust channel extending between an exhaust inlet aperture and an exhaust outlet aperture, the exhaust inlet aperture being defined by an inner surface of the shaft housing, the fluid chamber housing or the shaft housing and fluid chamber housing jointly, and the exhaust outlet aperture being defined by the out side surface of the shaft housing, the fluid chamber housing or the shaft housing and fluid chamber housing jointly.

22. A drill head according to claim 19 or claim 20, wherein the fluid exhaust passageway is an exhaust gap defined between the contact surfaces of attached shaft and the fluid chamber housings.

23. A drill head according to any one of claims 19 to 22, wherein the out side of the fluid chamber housing is cylindrically shaped.

24. A drill head according to claim 21 or claim 22 read together with claim 15, wherein the one or more internal seals are at least one first seal and one second seal, the first seal for preventing water and/or debris from contacting the mounting means and being located nearer the second bush or bearing than the second seal, and the second seal for sealing one end of the fluid chamber and being located nearer the fluid chamber than the first seal, such that the exhaust inlet aperture of the exhaust channel or the exhaust gap is located between the first and second seals.

25. A drill head according to claim 24, wherein the drill head further comprises at least one third seal and one fourth seal, the third seal for preventing water and/or debris from contacting the mounting means and being located nearer the first end of the shaft housing than any of the other seals, and the fourth seal for sealing the end of the fluid chamber opposite the end at which the second seal is located. WO 2010/019972 PCT/ZA2009/000074 -16

26. A drill head according to claim 25, wherein any one or more of the at least one first, second, third and fourth seals are a pair of first, second, third and fourth seals, the respective pair of seals being spaced apart from one another to define a lubrication chamber for receiving a lubricant therein.

27. A drill head according to claim 26, wherein the lubricant is from a group including grease or oil lubricants.

28. A drill head according to any one of the preceding claims wherein the drill head further includes a means for driving the shaft of the drill head.

29. A drill head according to claim 28, wherein the drive means is an electric, pneumatic, hydraulic or any other type of drive motor.

30. A drill head according to claim 28 or claim 29, wherein the drill head further includes an adaptor plate for releasably coupling the drill head to the drive means.

31. A drill head according to claim 28, claim 29 or claim 30, wherein the drill head further includes a means for mounting the drill head and drive means to a drilling rig.

32. A drill head according to claim 31, wherein the mounting means is a mounting bracket.

33. A fluid chamber housing for a drill head, the fluid chamber housing defining an inner cavity for housing at least a portion of the drill head shaft and including: seal receiving formations, wherein co-operation between the inner side of the fluid chamber housing and seals received in the seal receiving formations define a fluid chamber; a fluid chamber inlet for introducing pressurised fluid into the fluid chamber; and means for releasably attaching the fluid chamber housing to the drill head.

34. A fluid chamber housing according to claim 33, wherein the fluid chamber housing is WO 2010/019972 PCT/ZA2009/000074 -17 attachable to the drill head with a plurality of bolts, studs and/or nuts.

35. A fluid chamber housing according to claim 33 or claim 34, wherein a fluid exhaust passageway is defined by the fluid chamber housing, the drill head or the fluid chamber housing and drill head jointly so as to, in the event of seal failure, exhausting fluid therefrom thereby providing a visual indication of seal failure.

36. A drill head substantially as herein described and illustrated.

37. A fluid chamber housing substantially as herein described and illustrated.