GB2098645A - Mining machine - Google Patents

Abstract

A mining machine 1, particularly for coal winning operations, comprises an electric motor powering inter alia a water pump 17, a transmission 6, 7, 8, 12, 13, 14, 19, 20, 21 and 22, from the electric motor to at least one rotary cutting head, the transmission incorporating a clutch 18, and a water pressure sensing device 31 (not shown) controlling the clutch 18, whereby the latter may not be engaged in a drive condition until a predetermined water pressure as been obtained. <IMAGE>

Description

SPECIFICATION Mining machine This invention relates to a mining machine, par ticularlythough not exclusively for use in coal winning operations.

In the longwall mining technique, in contrast to the room and pillar technique, a mineral mining machine is reciprocated along a mineral face to remove a web of material. However, with whatever technique is involved, conventional mineral winning machines are provided with at least one rotary cutting head, provided with picks, the head being driven through a transmission, from an electric motor mounted in the machine body and the head usually being displaceable with respect to the machine e.g.

by being mounted on a ranging arm pivotally attached to the machine body, whereby undulations of the seam may be followed and/or roadway ripping operations may be effected at one or both ends of the mineral face. In principle, longwall machines are provided with one or two cutting heads dependent upon whether they are single-ended or doubleended machines, while continuous mining machines have at least one leading end cutting head.

In order to control and dilute methane etc.

released at the face, it is standard practice to ventilate the face by coursing an air supply along the face.

In addition a known technique, known as hollow shaft ventilation, is to force by means of a water pump, a high pressure water supply e.g. at 15002000 p.s.i., to the cutting head to convey diluting air along a hollow shaft on which the rotary cutting head is mounted, from the goaf side to the face side of the head, where of course methane etc. release occurs, but the jet or mist of water droplets serving additional dust suppression purposes. Such a system has proved generally satisfactory, even where fissures are encountered with the consequent release of large volumes of methane but requires a high pressure hose extending from the water pump which is conventionally located in a roadway at one end of the face, with further, low pressure hose to convey water e.g. at 300-400 p.s.i. for what is known as pick face flushing, for the main dust suppression effect.

According to the present invention, a mining machine particularly for coal winning operations comprises an electric motor powering inter alia a water pump, a transmission from the electric motor to at least one rotary cutting head comprising a clutch, and a water pressure sensing device controlling the clutch, whereby the latter may not be engaged in a drive condition until a predetermined water pressure has been obtained.

By providing the machine with a water pump, firstly, the high pressure hose and its roadway located pump may be dispensed with, and secondly, the controlling of the clutch by water pressure ensures in practice that rotation of the cutting head cannot be effected until a supply of water and hence entrained air has previously been supplied to the cutting head, to have at least some diluting effect, and hence serves in practice as a pre-start warning system to personnel in the vicinity of the machine.

The machine carried water pump in effect boosts the low pressure water e.g. at 300-400 p.s.i. available to the machine along the low pressure hose.

The clutch is conveniently of the friction type. Preferably, an additional safety feature in the form of a brake on the output side of the clutch is provided, to prevent chance rotation of the cutting head resulting from any clutch drag occurring upon clutch disengagement. It is also preferred for the machine to incorporate means whereby the drive to the cutting head is automatically engaged after a pre-set period of time, by putting the clutch into a drive condition, without the need to halt the electric motor. Additional and preferred safety features also include means to halt rotation of the cutting head if the water flow fails completely or falls below a predetermined threshold, or alternatively rises above a predetermined threshold indicating e.g. blocked water jet(s).

In detail, with a longwall mining machine, the clutch may be provided either in a gearhead of the machine or in a ranging arm containing transmission gearing, the arm carrying at one end a rotary cutting head and being pivotally mounted at the other end to the machine.

In detail, a single- or multi- plate clutch may be provided operable hydraulically under the control of the pressure sensing device.

The invention is particularly suitable for what is known as a buttock shearer where the supply of fresh air along the face does not always have an optimum diluting effect.

The invention will now be described in greater detail, by way of example, with reference to the accompanying schematic drawings, in which: Figure lisa diagrammatic plan view of a mining machine in accordance with the invention, with the contents of a gearbox of the machine indicated; and Figure 2 is a hydraulic circuit for the gearbox of Figure 1.

The mining machine 1 illustrated in the drawings is of the shearer type comprising a plurality of modules for different machine functions. Thus the machine comprises a module 2 housing an electric motor and supplying power to a module 3 in the form of a gearbox, which in turn supplies power to a module 4 of a cutting drive incorporating a ranging arm 5 pivotally attached to the cutting drive module 4 and carrying a rotary cutting head (not shown). If the machine is of the double-ended kind, then a second cutting drive module 4A with its ranging arm 5A is provided at the other end of the machine 1.

As indicated in Figure 1, a motor output shaft 6 is connected to a gearbox input shaft 7 carrying a pinion 8 in mesh firstly with a gear wheel 9 which, via drive shaft 10, powers an oil pump 11, and secondly with a gear wheel 12 having a drive shaft 13 carrying a pinion 14 in mesh with a gear wheel 15 which, via a drive shaft 16, powers a water pump 17. The drive shaft 13, beyond the pinion 14 is drivably connected to first elements of a clutch 18, engageable hydraulically by means of oil supplied from the pump 11, and spring disengaged, as will be described in detail later. When the clutch is engaged, other clutch ele ments, connected to a clutch output shaft 19 serve to drive a pinion 20 in mesh with a gearwheel 21 car ried by a gearbox module output shaft 22.An exten sion 23 of the output shaft 22 carries an element 24 on which is operable a spring released, hydraulically engaged, brake 25. Power from the output shaft 22 is transmitted to the cutting drive module 4 (and 4A, if present via a transmission shaft which is not illustrated) and dependent upon the cutting conditions, further speed reduction may be effected in the transmission train, either in the module 4, 4A, or in the ranging arm 5, 5A.

As indicated in Figure 2, when the water pump 17 is being rotated by drive shaft 16, water, at whatever pressure it is supplied from a supply source to the machine 1, is boosted to the designed output pressure of the pump 17 and fed along delivery line 26 to one or more ventilation jets 27 which in addition to supplying a jet or mist of water in the vicinity of discharge, also entrains air, and in practice conveys air to the mineral face where, in the case of coal mining, methane is continuously being released in random quantities, whereby methane dilution to safe levels is achieved. Tapped into the line 26 is a line 28 leading to a relief valve 29 to relieve water pressure should the jet(s) 27 become blocked e.g. by coal dust, slurry etc.Also tapped into the line 26 is a line 30 to convey water to a pre-set pressure switch 31 with an output line 32 operable on one end 33 of a change-over valve 34 of an oil circuit 35 supplied with pressure fluid by the oil pump 11. The latter has an output line 36, incorporating a relief valve 37, and leading to the change-overvalve 34. Beyond the relief valve 37 is a line 38 leading to the clutch 18, for clutch cooling purposes with an adjustable throttling valve 39 in a line 40 leading to an oil reservoir 41.

The change-over valve 34 is connected via line 42 to the tank 41, via line 43 to the clutch 18 and via line 44 to the brake 25, the clutch 18 being disengaged by spring 45 which is overcome by oil pressure supplied to chamber 46, while the brake 25 is disengaged by spring 47 and engaged by oil pressure supplied to chamber 48.

in the relative positions of the components illustrated in Figure 2, no drive to the ranging arm 5, 5A and hence to the rotary cutting head carried thereby is taking place, the clutch 18 being disengaged, and the brake 25 being engaged. After a predetermined period of operating time of the water pump 17, water pressure will build up in the line 26 and exceed the predetermined setting of the pressure switch 31 thereby allowing water pressure to line 32 and hence changing over the valve 34 from the position illustrated where line 36 is connected to line 44 and line 43 is connected to line 42 and hence to the tank 41, to the changed over position where line 36 becomes connected to line 43 and line 44 becomes connected to line 42 and hence to the tank 41, whereupon the clutch 18 becomes engaged and the brake 25 simultaneously becomes disengaged and drive to the cutter drive module 4, 4A, takes place.

Claims (10)

1. Amining machine particularly for coal win ning operations comprising an electric motor power ing inter alia a water pump, a transmission from the electric motorto at least one rotary cutting head comprising a clutch, and a water pressure sensing device controlling the clutch, whereby the latter may not be engaged in a drive condition until a predetermined water pressure has been obtained.

2. A mining machine as claimed in Claim 1 wherein the clutch is ofthe friction type.

3. A mining machine as claimed in Claim 1 or Claim 2, comprising a brake on the output side of the clutch.

4. A mining machine as claimed in any preceding Claim, incorporating means whereby the drive to the cutting head is automatically engaged after a pre-set period of time, by putting the clutch into a drive condition, without the need to halt the electric motor.

5. A mining machine as claimed in any preceding Claim, comprising means to halt rotation of the cutting head if the water flow fails completely or falls below a predetermined threshold, or alternatively rises above a predetermined threshold.

6. A mining machine as claimed in any preceding Claim, in an embodiment where the machine is a longwall mining machine, wherein the clutch is provided in a gearhead ofthe machine.

7. A mining machine as claimed in any one of Claims 1 to 5, in an embodiment where the machine is a longwall mining machine, wherein the clutch is provided in a ranging arm containing transmission gearing, the arm carrying at one end a rotary cutting head and being pivotally mounted at the other end to the machine.

8. A mining machine as claimed in any preceding Claim, wherein the clutch is of the single- or multiplate kind.

9. A mining machine as claimed in any preceding Claim, wherein the clutch is operable hydraulically underthe control ofthe pressure sensing device.

10. A mining machine substantially as hereinbefore described with reference to the accompanying drawings.