WO2012151624A1

WO2012151624A1 - Drive system

Info

Publication number: WO2012151624A1
Application number: PCT/AU2012/000496
Authority: WO
Inventors: Steven CHANDLER; Maohu Matthew WANG
Original assignee: Yancoal Australia Ltd; Caterpillar Global Mining Europe Gmbh
Priority date: 2011-05-09
Filing date: 2012-05-09
Publication date: 2012-11-15
Also published as: AU2012253219B2; AU2012253219A1

Abstract

A drive system for driving a conveyor associated with long wall mining equipment, including: a drive frame with a cradle that supports a return shaft for driving a conveyor; a drive unit with a drive motor arranged substantially parallel to the conveyor and adjacent to the frame and a rotatable output member arrange to rotate about an axis of the motor, in a direction substantially orthogonal to the shaft; a gearbox for translating rotary movement transversely of the output member into rotary movement of an output gear about a second axis, parallel to the return shaft, the output gear being coupled to the shaft to drive the conveyor; wherein the drive unit is arranged in line with the drive frame and conveyor; and the output gear of the gearbox is coupled to the return shaft through a geared transmission to accommodate the in line arrangement of the drive unit and drive frame.

Description

DRIVE SYSTEM

Related Application

[0001] This application claims priority from Australian Patent Application No. 201 1901740 filed 9 May 201 1 , the contents of which are incorporated by reference.

Field of the Invention

10002] The present invention relates to drive system for use in driving a conveyor associated with a long wall top caving (LTCC) assembly.

Background of the Invention

[0003] Long wall top coal caving (LTCC) is a method used in coal mining for the extraction of coal from a long, generally thick coal seam. Referring to Figure 1 , there is shown a first example of a LTCC assembly (1) which is suitable for the LTCC method. This first example of a LTCC assembly (1) includes a beam stage load and crusher (4) which conveys coal out of the longwall and a coal extraction arm (5) arranged generally perpendicular to the beam stage load and crusher (4). The coal extraction arm (5) is located along the mine shaft adjacent to the coal seam which is to be extracted. A roadway shield (12) is provided at the transition between the coal extraction arm (5) and the beam stage loader and crusher (4) to provided support to the roof of the mine shaft.

[0004] The coal extraction arm (5) includes a main gate end (2), a tail gate end (3), a face side (8) and an opposing goaf side (9). Between the main gate end (2) and the tailgate end (3) there is provided a plurality of shields, including transition shields (6), run of face shield (14) and larger 6-legged end gate shields (7), which are utilised to support the roof of the mine shaft. [0005] The coal extraction arm (5) further includes a front armour face conveyer (AFC) (10) with a front pan line (15) located adjacent to the face side (8) and a rear AFC (1 1) with a rear pan line (16) located adjacent to the goaf side (9). The front AFC (10) is driven by a front AFC main gate drive (21) and a front AFC tail gate drive (22), located at the main gate end (2) and the tail gate end (3), respectively. The rear AFC (10) is driven by a rear AFC main gate drive (24) and a rear AFC tail gate drive (25), located at the main gate end (2) and the tail gate end (3), respectively. The front AFC (10) and the rear AFC (1 1) travel beneath the transition shields (6) and run of face shields (14). The front AFC main gate drive (21 ), the front AFC tail gate drive (22), the rear AFC main gate drive (24) and the rear AFC tail gate drive (25) are located beneath the larger 6-legged end gate shields (7).

[0006] In operation, the coal extraction arm (5) is advanced into the coal seam in the direction indicted by arrow (A) by cutting the coal seam along face side (8) and moving the shields (6, 7) towards the coal face. The cut coal is conveyed by the front AFC (10) to the beam stage load and crusher (4). Before the shields (6, 7) are moved towards the coal seam, the roof of the seam towards the goaf side (4) is allowed to collapse or "cave in". The shields (6) are configured to direct the collapsed coal to the rear AFC (1 1) which conveys the coal to the beam stage load and crusher (4). Importantly, the transition shields

(6) , run of face shield (14) and the 6-legged end gate shields (7) are required to operatively support the roof of the mine shaft whilst the coal extraction arm (5) proceeds into the coal seam.

[0007] Referring to Figures 2 and 3, there is shown an example 6-legged end gate shield

(7) which includes a ground engaging pontoon (30), hydraulic legs (31) and a canopy (32). The pontoon (30) supports the hydraulic legs (31 ) which in turn support the canopy (32). The canopy (32) includes a front canopy (33) and rear canopy (34). The front canopy (33) and rear canopy (34) are moveable to control the height and length of the canopy (32). In particular, the rear canopy (34) is able to protect the main gate and tail gate drives of rear AFC. [0008) The pontoon (30) is located between the front AFC tailgate drive (22) and the rear AFC tailgate drive (25). Due to the width of the front AFC tailgate drive (22) and the rear AFC tailgate drive (25), the pontoon (30) is of relatively narrow width in comparison to the width of the canopy (32), in order to provide space to accommodate the front AFC tailgate drive (22) and the rear AFC tailgate drive (25).

|0009] As such, the support base for the legs (31) is relatively small and the legs (31) are themselves of a restricted size, in order to fit between the two drives (22) and (25). This limits the ability of the legs (31) and thereby the rear canopy (34) to support the roof load, which can cause the rear canopy to collapse and become pressed against the rear AFC tailgate drive (25), which in turn may cause damage to the rear AFC tailgate drive (25) and/or the rear canopy (34). Moreover, this may result in an uncontrolled roof collapse in and around the rear AFC tailgate drive (25) which presents a danger to personnel as well as a disruption to operations.

[0010] Furthermore, referring to Figure 4, it may be appreciated that the front AFC tailgate drive (22) and the rear AFC tailgate drive (25) are spaced apart to accommodate the pontoon (30). As the coal extraction arm (5) is generally of a narrower width than the overall width defined by the shields (7) protecting the front AFC tailgate drive (22) and the rear AFC tailgate drive (25), the rear (AFC) is required to bend inwardly and is therefore not straight which may cause undue wear to the components of the rear AFC (1 1).

[00111 In an attempt to address the problems associated with this first described example of an LTCC assembly (1), a second LTCC assembly (50) was proposed, as illustrated in Figure 5. In this LTCC assembly (50), the 6-legged end gate shields (7) are moved in from the tailgate end (3), towards the main gate end (2), and replaced with 4- legged buttress shields (13), which are located immediately adjacent the tailgate end (3). This LTCC assembly (50) allows for the buttress shields (6), which are able to withstand a higher top loading than the 6-legged end gate shields (7), to support the roof above the tail gate end (3) of the LTCC assembly (50). The LTCC assembly (50) also includes 2-legged run of face shields (14) located between the 6-legged end gate shields (7) and the main gate end (2).

[0012] Referring additionally to Figures 6a and 6b, in this LTCC assembly (50), the front AFC tail gate drive (22) is located beneath the 4-legged buttress shields (13) and the rear AFC tailgate drive (25) is located beneath the 6-legged end gate shields (7). As such, the front AFC tail gate drive (22) has been longitudinally offset from the rear ARC tailgate driver (25). This allows for the lateral spacing between the front AFC tail gate drive (22) and rear AFC tailgate drive (25) to be reduced so that the front AFC (10) and the rear AFC (1 1 ) are generally straighter than the front AFC (10) and the rear (AFC) of the first LTCC assembly (1), as represented in Figures 6a and 6b.

[0013] A problem with this second proposed LTCC assembly (50) is that the use of the end gate shields (7) over the rear tailgate AFC drive (25) has still proved to be problematic. In particular, the size of the rear tailgate AFC drive (25) still requires use of the less well supported shields (7), such as illustrated in Figures 2 and 3, with a relatively narrow pontoon (30) and a poorly supported rear canopy (34). Therefore, similarly to the first example of the LTCC assembly (1 ), this LTCC assembly (50) also suffers from uncontrolled roof collapses in and around the rear AFC tailgate drive (25). The legs supporting the 6-legged end gate shields (7), the 4-legged buttress shields (13) and the 2- legged face shields (14), either side of the drive (25) also serve to obstruct removal of collapsed material, increasing the disruption to operations after such a collapse.

Summary of the Invention

[0014] In accordance with the invention, there is provided a drive system for driving a conveyor associated with long wall mining equipment, including: a drive frame with a cradle that supports a return shaft for driving a conveyor; a drive unit with a drive motor arranged substantially parallel to the conveyor and adjacent to the frame and a rotatable output member arrange to rotate about an axis of the motor, in a direction substantially orthogonal to the shaft; a gearbox for translating rotary movement transversely of the output member into rotary movement of an output gear about a second axis, parallel to the return shaft, the output gear being coupled to the shaft to drive the conveyor; wherein the drive unit is arranged in line with the drive frame and conveyor; and the output gear of the gearbox is coupled to the return shaft through a geared transmission to accommodate the in line arrangement of the drive unit and drive frame.

(0015] In accordance with the invention, there is provided a drive system for driving a conveyer associated with a long wall top coal caving (LTCC) assembly, the drive system including a drive unit, a drive frame which is adapted to operatively support at least part of the conveyer and a transmission which is coupled between the drive frame and the drive unit so as to transfer drive from the drive unit to the conveyer, wherein the drive unit is arranged inline with the drive frame.

[0016] In another aspect, there is provided a transmission for connecting a drive unit with a drive frame of a long wall top coal caving system (LTCC) including a housing positioned laterally of a motor of the drive unit and a side of a drive frame which carries a conveyor to thereby enable the drive unit to drive the conveyor from a location in-line with the conveyor via the laterally positioned transmission.

(0017] In another aspect, there is provided a tailgate from an LTCC assembly including a drive system, as described above, positioned at an end of the tailgate, and a conveyor arranged whereby the drive unit and conveyor are in-line and drive is transferred from the drive unit to the conveyor via a transition gearbox located laterally of the drive unit and conveyor.

(0018] In yet another aspect, there is provided a long wall top coal caving assembly, including a drive system, as described above.

Brief Description of the Drawings

(0019] The invention is described, by way of non-limiting example only, by reference to the accompany drawings in which: Figure 1 is a perspective view of a first example of a LTCC assembly;

Figure 2 is an example of a 6 legged end gate shield located between a front AFC tailgate drive and the rear AFC tailgate drive;

Figure 3 is a side view of the 6 legged end gate shield of Figure 2;

Figure 4 is a top view of a tailgate end of the first LTCC layout shown in Figure 1 with shields removed to view a rear AFC tailgate drive and the front AFC tailgate drive- Figure 5 illustrates a perspective view of a second example of a LTCC assembly;

Figure 6a illustrates a top view of the tailgate of the second example of the LTCC assembly shown in Figure 5 with the shields present;

Figure 6b illustrates a top view of the tailgate of the second example of the LTCC assembly shown in Figure 5 with the shields removed to view a rear AFC tailgate drive and the front AFC tailgate drive;

Figure 7 is a perspective view of the inline rear AFC tailgate drive system showing a drive unit coupled by a transmission to a drive frame;

Figure 8 is a top view illustrating the inline rear AFC tailgate drive system as shown in Figure 7;

Figure 9 illustrates a top view a tailgate end of another example of a LTCC assembly, the inline rear AFC tailgate drive assembly is coupled to a rear AFC, and a front AFC drive is coupled to a front AFC; Figure 10 is a perspective view of the inline rear AFC tailgate drive system positioned beneath a series of shields;

Figure 1 1 is another perspective view of the inline rear AFC tailgate drive system positioned beneath a series of shields;

Figure 12 is another perspective view of inline rear AFC tailgate drive system positioned beneath a series of shields;

Figure 13 is another perspective view of the inline rear AFC tailgate drive system positioned beneath a series of shields;

Figure 14 is a perspective view of a transmission;

Figure 15 is a sectional view of the transmission;

Figure 16 is an exploded view of a drive system; and

Figure 17 is a perspective view of the assembled drive system of Figure 16.

Detailed Description of the Invention

[0020] Referring to Figures 7 and 8, there is shown an inline rear AFC tailgate drive system (100) for use in driving a conveyor (1 10), specifically in the form of a rear tailgate armoured face conveyor (AFC) associated with a long wall top coal caving (LTCC) assembly.

[00211 The drive system (100) includes a drive unit (106) including a motor (104), a main gear box (1 12) and a drive frame (102) which is adapted to support at least part of the conveyor (1 10). The drive system (100) further includes a transmission (1 14) which is coupled between the drive frame (102) and the drive unit (106) so as to transfer drive from the drive unit (106) to the conveyor (1 10).

[0022] The transmission (1 14) couples the drive unit (106) in an end-to-end relationship with drive frame (102). As such, a longitudinal axis of the drive unit (106) is able to be substantially aligned with the longitudinally axis of the rear tailgate AFC (1 10).

[0023] The drive system (100) includes a flange plate (1 16) supported by the drive frame (102). The flange plate (1 16) is located between the transmission (1 14) and the main gear box (1 12) thereby interconnecting the transmission (1 14) and the main gear box (1 12) relative to the drive frame (102).

[0024] The drive frame (102) includes an elongate body (120) with laterally spaced apart walls (122, 124), a top face (126) and a bedplate (128). A cradle (130) of the drive frame includes aligned bores (132) through the first and second opposing sides (122, 124) which defines a space (135) therebetween in which a horizontally disposed return shaft (155) (shown in Figure 8) is in use positioned to drive a chain and flight bar conveying mechanism (not shown) of the rear AFC.

[0025] The top face (126) of the drive frame (102) includes a ramped portion (134) to guide the aforementioned chain and flight bar conveying mechanism in relation to the horizontally disposed return shaft (155).

[0026] In one form, the bedplate (128) is configured to extend beneath the motor (104) and drive unit (106) thereby allowing the motor (104) and drive unit (106) to be seated on the bedplate (128) and/or at least a flanged rim (140) associated with the bedplate (128). This is envisaged to assist to better integrally couple the drive unit (106) with the drive frame (102).

[0027] The transmission (1 14) includes a housing (150) which houses an input gear (152) and an output (154). The input gear (152) is coupled to an output gear (156) associated with the main gearbox (1 12) and the output gear (154) is coupled to the horizontally disposed shaft (155) mounted through the axial bores (132) of the drive frame (102). The input gear (152) and the output gear (154) each include a sprocket (not shown) which are coupled, either directly or by a chain drive, such that the input gear (152) and the output gear (154) turn synchronously. Overall, the gear ratio of the transmission (1 14) is 1 :1. However, this may be varied by, for example, adjusting the diameter of the sprocket associated with one or both of the input gear (152) or the output gear (154).

[0028] In one form, the main gearbox (1 12) and motor (104) have a weight of about 20 tonnes. The longitudinal length of the main gear box (1 12) and motor (104) is in the order of 4.5 meters. The drive frame (102) weight is about 35 tonnes and the length of the drive frame is in the order of 5.5 meters. The overall length of drive system (100) will then be in the order of 10.5 meters, have an overall height of about 1.5 meters and an overall width of approximately 2.3 meters. It is envisaged the width of the transmission (1 14) will be less than approximately 0.5 m. The main gear box (1 12) may be a P45/65 type and have an auto-chain tension stroke of 1 m.

[0029] Referring to Figures 9 to 13, the inline rear AFC tailgate drive system (100) is able to be installed at a tailgate end (3) of an LTCC assembly (160).

[00301 Advantageously, due to the inline positioning of the drive unit (6) and the drive frame (102) the rear AFC tailgate drive system (100) has significantly less width than the rear AFC tailgate drive (25) associated with the first and second LTCC assemblies (1 , 50). Therefore, the inline rear AFC tailgate drive system (100) is able to be placed generally on an opposite side of a pontoon (162) of a shield (164) from a front AFC tailgate drive (166) without needing to be longitudinally offset from the front AFC tailgate drive (166), as is the case in the second example of the LTCC assembly (50). Moreover, the reduced width of the inline rear AFC tailgate drive system (100) allows the inline rear AFC tailgate drive system (100) to be located relatively closer to the front AFC tailgate drive (166). This allows the front AFC (168) and rear AFC (170) to be substantially parallel, as may be best appreciated from Figure 9, thereby reducing the wear on conveyor components, such as the flight bars, caused by pan lines (172, 174) of the respective front and rear AFC's (168, 170) not being substantially straight such, as in the arrangements of Figures 1 to 6.

{0031] Moreover, as the overall width of the inline rear AFC tailgate drive system (100) has been reduced, an increase in the width of the pontoon (164) can be accommodated. This allows for an increased support base to support a comparatively longer pontoon (164) in comparison to the canopy (176).

[0032] In particular, the drive system (100), by allowing a wider pontoon (164), allows the canopy support cylinders (176) to be more widely spaced and therefore provide a more direct load path to the canopy (176), in particular, the rear canopy (178) to thereby provide greater support to the roof. Furthermore, the rear canopy (178) is able to be shortened thereby reducing the moment forces which the rear canopy (178) is exposed to in use. This can help reduce uncontrolled collapse at the trailing end (9) and assist in preventing the rear canopy (178) from becoming overloaded and/or becoming forced against the drive system (100).

(0033] It should also be appreciated that since the drive system (100) and the front tailgate drive (166) are able to be located adjacent one another and at the end of the tail gate (3), unobstructed access to the drive system (100) is provided, which allows for clearing away of collapsed material and/or general maintenance, without needing to navigate past support legs of adjacent shields, such as required in relation to the second example of the LTCC system (50).

[0034] Referring now to Figure 14, an alternative form of a geared transmission (200) is shown as including an elongate, rectangular shaped housing (201) that houses a input gear (202) and an output gear (203) arranged to rotate about parallel axes.

[0035] The transmission (200) has a front torque support (204) and a rear torque support (205). The front torque support (204) is in the form of an elongate extension of the housing (201). The rear torque support is in the form of a lateral projection (206). [0036] As shown in Figure 15, the input gear (202) and output gear (203) are arranged in alignment and are interconnected by a third gear (207), so that the input and output gears (202) and (203) can rotate in unison, in the same direction with a gear ration of 1 : 1. In the example shown, the first and second gears (202) and (203) each have 41 teeth and the third gear (207) has 42 teeth. However, any suitable number of teeth or drive configuration can be adopted, as required, provided the transmission (200) is capable of transferring rotational input into adjacent and laterally offset rotational output.

[0037] Also, the dimensions of the transmission (200) can be varied to suit, however, in the example shown, the length dimension is of the order of 4720mm, the height dimension is in the order of 1060mm, and the width dimension is in the order of 620mm. The weight load of the transmission (200) is preferably about 1 1,000 kg with a required oil capacity of 220 litres.

(0038) Vibration sensors can be fitted to the transmission but any vibration or torque movement generated by cantilevered transfer of forces through the geared transmission is preferably absorbed by the torque supports (204) and (205).

[0039] The transmission (200) also includes ports (208) that connect to internal heat exchange circuits that may be water cooled with a water supply of 25 litres per minute at about 30 bar, in order to maintain the oil temperature within the transmission (200) at sufficiently reduced temperatures.

[0040] Referring now to Figure 16, an exploded view of a drive system (210) is illustrated. The system (210) includes a drive frame (21 1) mounted on a bedplate (212). The bedplate (212) provides a substructure to carry all the components of the drive system (210) and helps to distribute the weight evenly onto a supporting floor surface. Skids (209) are provided on the underside of the bedplate to facilitate sideways shunting of the system (210), which is needed as the rear AFC conveyor is advanced after a coal caving cycle. (0041) The frame (21 1) is formed of a conveyor support section (213) and a cradle (214) that carries a return shaft (215), for driving a conveyor. The cradle can be moved a total distance of about l m relative to the conveyor support section (213) by piston actuators (216) in order to vary the tension applied from the drive shaft (215) to a chain of the conveyor.

(0042) A baffle plate (217) is arranged to fit on a rear of the cradle (214) and includes a ratchet pawl that is used to lock a drive sprocket of the shaft (215) when the AFC chain needs to be removed for maintenance or adjustment.

[0043] The system (210) also includes a drive unit (218) that has a three phase drive motor (219) and is connected via drive connection (220) to a gearbox (221 ). Both the gearbox (221) and the drive unit (218) are arranged in-line with the drive frame (21 1 ). In that configuration, the transmission (200) allows drive to be transmitted from the drive unit (218) to the shaft (215), via the gearbox (221).

(0044) More specifically, as shown in Figure 17, the transmission (200) is fitted between the drive unit (218) and the drive frame (21 1) by being bolted to the gearbox (221) so that the rear torque support is engaged with the gearbox (21 1) and the output gear of the gearbox (21 1) is connected directly to the input gear of the transmission (200). The transmission (200) extends along a lateral side of the drive frame (21 1) and connects directly to a support plate (222) of the cradle (214) so that the output gear (203) fits with and drives the shaft (215) while the front torque support (204) is bolted to plate (222) to absorb any torque generated by the cantilever configuration of the transmission. The torque support (204) thereby serves to reduce wear on the working gears and bearings of the system (210).

[0045] In relation to the gearbox (221), this is preferably in the form of a standard KP65 Gearbox. This type of gearbox was conventionally placed in side-by-side relation to the drive frame (21 1) so as to drive the shaft (215) directly. As such, in the side-by-side configuration, the gearbox was bolted directly to the drive frame and no torque support was required. However, in that arrangement, the gearbox contributed to the extra width dimension of the drive system and resulted in all the various attendant problems of the prior art.

(00461 In the present configuration, the gearbox (221) provides a similar function in so far as the gearbox (221) translates drive laterally of the drive unit (218). However, instead of being plugged directly onto the shaft (218), the rotational output of the gearbox is instead fed into the transmission (200) that translates it laterally to the shaft (215). More particularly, an output member of the drive unit is connected directly to an input gear of the gearbox so that rotary movement of the output member about an axis of the unit (218) causes corresponding rotation of the output gear of the gearbox about a transverse second axis. The second axis is substantially parallel to the shaft (215) and the transmission (200) provides the bridging force transmission so as to allow functional co-operation between the drive unit (218) and drive frame, despite the inline configuration.

(0047] It should be appreciated that the addition of the transmission (200) into the drive system (210) actually increases the complexity and required component parts of the system (210), relative a conventional drive system. However, the advantages resulting from such an arrangement are considerable from a point of view of allowing increased pontoon dimensions and support capacity for the shields, as well as allowing the rear AFC tailgate drive to be located at and end of line position, opposite the front AFC tailgate drive, thereby provided easy access for maintenance and coal clearing operations.

[0048] Many modifications and varieties may be made to the above described drive system and component parts without departing from the spirit and scope of the present invention.

J0049J The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0050] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

List of Parts

1. Long wall top caving assembly

2. Main gate end

3. Tail gate end

4. Beam stage load and crusher

5. Coal extraction arm

6. Transition shield

7. 6-legged end gate shield

8. Face side

9. Goaf side

10. Front armoured face conveyor (AFC)

1 1. Rear AFC

12. Roadway shield

13. 4-legged buttress shield

14. 2-legged face shield - not mark on drawing.

15. Front pane line

16 Rear pan line

21. Front AFC main gate drive

22. Front AFC tail gate drive

24. Rear AFC main gate drive

25. Rear AFC tail gate drive

30. Pontoon

31. Legs

32. Canopy

34. Rear canopy

50. LTCC assembly

100. Drive system

102. Drive frame

104. Motor

106. Motorised mechanism

1 10. Rear AFC 1 12. Main gearbox

1 14. Transmission

1 16. Flange plate

120. Elongate body

122. Wall

124. Wall

126. Top face

128. Bedplate

130. Cradle

132. Bores

134. Ramped portion

135. Space

140. Flanged rim

150. Housing

152. Input gear

154. Output gear

155. Drive shaft

156. Output gear

160. LTCC assembly

162. Pontoon

164. Shield

166. Front tailgate AFC drive

168. Front AFC

170. Rear AFC

172. Front pan line

174. Rear pan line

176. Canopy

178. Rear canopy

200. Transmission

201. Housing

202. Input gear 203. Output gear

204. Front torque support

205. Rear torque support

206. Later projection

207. Gear

208. Skids

210. Drive system

21 1. Drive frame

212. Bedplate

213. Conveyor support section

214. Cradle

215. Shaft

216. Actuators

217. Baffle plate

218. Drive unit

219. Motor

220. Connection

221. Gearbox

222. Plate

Claims

CLAIMS:

1. A drive system for driving a conveyor associated with long wall mining equipment, including:

a drive frame with a cradle that supports a return shaft for driving a conveyor; a drive unit with a drive motor arranged substantially parallel to the conveyor and adjacent to the frame and a rotatable output member arrange to rotate about an axis of the motor, in a direction substantially orthogonal to the shaft;

a gearbox for translating rotary movement transversely of the output member into rotary movement of an output gear about a second axis, parallel to the return shaft, the output gear being coupled to the shaft to drive the conveyor; wherein

the drive unit is arranged in line with the drive frame and conveyor; and the output gear of the gearbox is coupled to the return shaft through a geared transmission to accommodate the in line arrangement of the drive unit and drive frame.

2. The drive system of claim 1 , wherein the transmission has a housing that is adapted to be fitted laterally of the drive frame and the gearbox.

3. The drive system of claim 2, wherein the transmission has front and rear torque supports for connection to the frame and drive unit, respectively.

4. The drive system, of claim 3, wherein the front torque support is in the form of an elongate extension of the housing, arranged to couple to a side of the cradle.

5. The drive system of claim 4, wherein the rear torque support is in the form of lateral projections arranged to bolt to the gearbox adjacent the drive unit.

6. The drive system of claim 1, wherein the transmission includes a series of aligned gears, to provide a 1 : 1 drive ratio.

7. The drive system of claim 1 or 2, wherein the transmission includes three aligned gears, so that input and output gears of the transmission rotate in the same direction.

8. The drive system of any one of claims 1 to 7, wherein the transmission includes heat exchange circuits.

9. The drive system of claim Γ, further including a bedplate to support and distribute the combined weight load of the drive frame, drive unit, gearbox and transmission.

10. The drive system of claim 6, wherein the bedplate includes skids to facilitate sideward shunting of the system.

1 1. A long wall top coal caving assembly, including the drive system of claim 1.

12. A drive system for driving a conveyer associated with a long wall top coal caving assembly (LTCC), the drive system including a drive unit, a drive frame which is adapted to operatively support at least part of the conveyer and a transmission which is coupled between the drive frame and the drive unit so as to transfer drive from the drive unit to the conveyer, wherein the drive unit is arranged inline with the drive frame.

13. The drive system according to claim 12, wherein the longitudinal axis of drive unit is able to be substantially aligned with the longitudinal axis of drive frame.

14. The drive system according to claims 12 or 13, wherein the transmission is located to one side of the drive unit and the drive frame.

15. The drive system according to any one of claims 12 to 14, further including a flange plate located substantially along one side of the transmission, the flange plate extending between the drive frame and the drive unit so as to support the transmission relative to the drive frame and the drive unit.

16. The drive system according to any one of claims 12 to 15, wherein the drive unit includes a motor and the system further includes a gearbox with an input gear coupled to an output member of the drive unit and an output gear coupled to the transmission.

17. The drive system according to claim 16, wherein the motor is located at a first end of drive unit and the gearbox is connected to a second end of the drive unit.

18. The drive system according to claim 17, wherein the gearbox is located at least partially adjacent to the transmission.

19. The drive system according to claims 17 or 18, wherein the gearbox is directly connected to a housing of the transmission.

20. The drive system according to any one of claims 12 to 19, wherein the system includes a bedplate to support the drive unit, frame and transmission.

21. The drive system according to any one of claims 12 to 20, wherein the transmission has a drive ratio of 1 : 1.

22. A transmission for connecting a drive unit with a drive frame of a long wall top coal caving system (LTCC) including a housing positioned laterally of a motor of the drive unit and a side of a drive frame which carries a conveyor to thereby enable the drive unit to drive the conveyor from a location in-line with the conveyor via the laterally positioned transmission.

23. A tailgate of a long wall top coat caving assembly (LTCC), including a drive system as claimed in claims 1 or 12, positioned at an end of the tailgate, and a conveyor arranged whereby the drive unit and conveyor are in-line and drive is transferred from the drive unit to the conveyor via a transition gearbox located laterally of the drive unit and conveyor.

24. A drive system substantially as described herein with reference to the drawings and/or examples.

25. A transmission, substantially as described with reference to the drawings and/or examples.

26. A tailgate, substantially as described with reference to the drawings and/or examples.