GB2060115A - Power Transmission for Scraper Chain Conveyor - Google Patents

Abstract

Motor shaft (6, 8) and output shaft (14) are interconnected by epicyclic gear unit (10) of which annulus (15) can be braked progressively so that power is transmitted gradually to the output shaft. The annulus can be braked, as shown, by a multiple-disc brake (18) engaged hydraulically; alternatively, the annulus may be coupled to a pump in circuit with a flow restrictor. A further brake (25) is associated with shaft (8). Hydraulic motor (29) can be used to drive shaft (8) via gearing (27, 28). When conveyor chain tensioning operations are carried out. <IMAGE>

Description

SPECIFICATION Power Transmission Apparatus This invention relates to power transmission apparatus, e.g. for use with conveyors, which may be of the belt or scraper chain type, as are used extensively for handling bulk materials; A scraper chain conveyor of the kind conventionally located along a mineral face, e.g. a coal face, is made up of a plurality of individual pans articulated together end-to-end and is provided at both the head end and the tail end of the conveyor with a sprocket with at least the head end sprockets driven by power transmission apparatus comprising an electric motor, a fluid coupling and a gearbox.A primary disadvantage of all scraper chain conveyors is the inherent friction between the moving chain or chains, the flight bars attached thereto and the stationary deck plate and sidewalls of the pans, as well as mineral fines and debris in the return run of the conveyor. This results in a demand for the use of electric motor of increased horse power, which often produce overheating or failure of the fluid coupling, with a consequent loss of production if longwall mining is involved. Furthermore, scraper chain conveyors conventionally incorporate no brake, even when operating on gradients of say 1 in 8, as their inherent friction resuits in their halting within a few feet after the electric motor is switched off.Also, although the gearbox is usually a speed reduction gearbox incorporating spur and/or bevel gears, a known gearbox incorporates an epicyclic gear unit with the annulus constituted by a portion of the gearbox casing.

According to the present invention power transmission apparatus comprises a power input shaft and a power output means, the input shaft and the output means being interconnected by an epicyclic gear unit and the apparatus further including means to slow progressively rotation of the annulus of the epicyclic gear unit, whereby the power applied at the input shaft is transmitted gradually to the output means.

The above defined apparatus provides the advantage that a fluid coupling may be omitted, with the resultant saving of installation and maintenance costs, as well as precluding the possibility of fluid coupling failure and consequential costs. Thus the electric motor may be connected directly to the power transmission apparatus, e.g. by a male element of the motor engaging a female element of the power transmission apparatus.

Preferably, the means to cause progressive slowing of the speed of rotation of the epicyclic annulus comprises a brake, e.g. of the multi-disc type. Alternatively, such means could be constituted by a hydraulic pump pumping through a flow restriction device, an element of the pump being displaced by rotation of the annulus.

Preferably, the power output means comprises a gear wheel mounted on a power output shaft coaxial with the power input shaft. The gear wheel may be of the spur or bevel type depending on whether the electric motor and power transmission apparatus are at right angles to the conveyor by having their axes of rotation parallel to those of the gears of the gearbox, or in line with the conveyor by having the axes of rotation of the electric motor and the power transmission apparatus extending laterally with respect to the axes of rotation of the gears of the gearbox.

In detail, the power input shaft may terminate in a gear end constituting the sun wheel of the epicyclic gear unit in mesh with planet wheels mounted on a carrier attached to the power output shaft, the planet wheels also being in mesh with the annulus, an extension of which preferably carries rotatable disc elements of the annulus brake. In this case, pads of the annulus brake are carried by a static part of the power transmission apparatus.

In accordance with a further feature, the input shaft also carries elements of a further brake adapted to serve as a conveyor brake when the electric motor is switched off. Preferably, this further brake is again of the multi-disc type, the elements carried by the input shaft being the discs, with the pads carried by a normally stationary member. If the power transmission apparatus is intended to drive a scraper chain conveyor, the normally stationary member may conveniently be constituted as a worm wheel in mesh with a worm, the latter being drivable at relatively slow speed by an auxiliary motor, e.g. of the hydraulic type, and serving to effect chain tensioning operations when the main drive from the electric motor is switched off.

If the means for slowing progressively the annulus comprises a multi-disc brake, this is preferably operated hydraulically, as is the conveyor brake.

The invention also includes a gearbox for a conveyor provided with power transmission apparatus as defined above, and also a scraper chain conveyor provided with such a gearbox.

The invention will now be further described, in greater detail, by way of example, with reference to the accompanying sectional drawing which shows a power transmission apparatus, gearbox and scraper chain conveyor in accordance with the invention.

In the drawing, a power transmission apparatus is indicated at 1, a speed reduction gearbox at 2 and an armoured scraper chain conveyor at 3. Only a head end 4 of the conveyor 3 is illustrated, the conveyor 3 being driven via the apparatus 1 and the gearbox 2 from an electric motor 5, The motor 5 is provided with an externally splined, male power output element 6 engaging an internally splined female element 7 extending from a power input shaft 8 of the apparatus 1.

The power input shaft 8 terminates in a geared end 9 constituting the sun wheel of an epicyclic gear unit 10, the geared end 9 being in mesh with planet wheels 11 rotatably carried on pins 12 extending across a carrier 13 attached to a power output shaft 14, the planet wheels 11 also being in mesh with an annulus 1 5. The latter is provided with an extension 16 carrying a plurality of discs 17 of a multi disc brake 18, with pads 19 of the brake 18 carried by a static part 20 of the apparatus 1, the brake 18 being operable by supplying hydraulic fluid via a port 21 to an annular chamber 22 sealed by a piston ring 23.

The input shaft 8 also carries discs 24 of a multidisc conveyor brake 25, with pads 26 of the conveyor brake 25 carried by a normally stationary worm wheel 27 in mesh with a worm 28 drivable by a hydraulic motor 29. Again the conveyor brake 25 is hydraulically actuable by supplying pressure fluid to an annular chamber 30 sealed by a piston ring 31.

The apparatus 1 further comprises power output means 32 comprising a bevel gear 33 in mesh with a bevel gear 34 and constituting a first stage speed reduction of the gearbox 2. The bevel gear 34 is carried by a shaft 35 which also carries a spur gear 36 in mesh with a spur gear 37 to constitute a second stage speed reduction. The spur gear 37 is carried by a gearbox output shaft 38 attached to one half 39 of a coupling 40, the other half 41 being attached to a sprocket shaft 42 which carries a sprocket barrel 43 having two spaced apart sprockets 44 each to engage one of the twin outboard drive chains of the conveyor as the chains pass from the upper, conveying run to the lower return run in the conventional manner.

For clarity, the chains and their flight bars are not shown but the chain centre lines are illustrated at 45.

Starting of the conveyor is as follows. The electric motor 5 is switched on, the power input shaft 8 rotates, as does the annulus 15 of the epicyclic gear unit 10 and hence the output shaft 14 remains stationary. After a pre-set time, determined by a timer (not shown) to allow build up of fluid pressure for operating the hydraulic brakes 18,25 from a hydraulic pump (not shown) driven by the electric motor, pressure fluid is fed to the annulus brake 18 so that the annulus 1 5 is progressively brought to rest and simultaneously the output shaft 14 begins to rotate, reaching its maximum speed when the annulus 1 5 is halted, thereby driving the conveyor 3 thrugh the gearbox 2.

To stop the conveyor the electric motor 5 is switched off, fluid pressure being maintained on the annulus brake 1 8 until the motor 5 stops and hence the associated hydraulic pump stops. At the same time as the electric motor 5 is switched off, pressure fluid is diverted to the conveyor brake 25 so that the worm wheel 27, via the worm 28, halts rotation of the power input shaft 8 and hence brakes the conveyor 3.

To effect chain tensioning, the supply of pressure fluid is maintained, e.g. by a separate hand pump, to both the annulus brake 18 and the conveyor brake 25, and using a furather supply of pressure fluid from an external source, e.g. from the hydraulic power lines to mine roof supports if the conveyor involved is a mine face conveyor, the hydraulic motor 29 is operated to rotate the worm 28 and hence rotate the worm wheel 27, causing the conveyor 3 to run at slower speed suitable for chain tensioning operations.

Conveniently a common lubricating oil supply is provided for both the power transmission apparatus 1 and the speed reduction gearbox 2.

Preferably, the apparatus incorporates various safety devices. For instance a sensor is preferably provided to sense that the fluid pressure of the conveyor brake 25 is zero before the electric motor 5 may start up. Also, a temperature sensor may provide for shut-down upon a predetermined temperature level being reached. Finally, a wear indicator may be provided for the pads of the conveyor brake 25.

Claims (21)

Claims

1. Power transmission apparatus comprising a power input shaft and a power output means, the input shaft and the output means being interconnected by an epicyclic gear unit and the apparatus further including means to slow progressively rotation of the annulus of the epicyclic gear unit, whereby the power applied at the input shaft is transmitted gradually to the output means.

2. Apparatus as claimed in Claim 1, wherein the means to cause progressive slowing of the speed of rotation of the epicyclic annulus comprises a brake.

3. Apparatus as claimed in Claim 2, wherein the brake is of the multi-disc type.

4. Apparatus as claimed in Claim 1, wherein the means to cause progressive slowing of the speed of rotation of the eyicyclic annulus comprises a hydraulic pump pumping through a flow restriction device, an element of the pump being displaced by rotation of the annulus.

5. Apparatus as claimed in any preceding Claim, wherein the power output means comprises a gearwheel mounted on a power output shaft coaxial with the power input shaft.

6. Apparatus as claimed in Claim 5, wherein the gear wheel is of the spur type.

7. Apparatus as claimed in Claim 5, wherein the gear wheel is a bevel gear.

8. Apparatus as claimed in Claim 5 and any claim appendant thereto, wherein the power input shaft terminates in a geared and constituting the sun wheel of the epicyclic gear unit in mesh with planet wheels mounted on a carrier attached to the power output shaft, the planet wheels also being in mesh with the annulus.

9. Apparatus as claimed in Claim 8, wherein an extension of the annulus carries rotatable disc elements of the annulus brake.

10. Apparatus as claimed in Claim 8, wherein pads of the annulus brake are carried by a static part of the apparatus.

11. Apparatus as claimed in Claim 5 and any Claim appendant thereto, wherein the input shaft also carries elements of a further brake adapted to serve as a conveyor brake when the electric motor is switched off.

12. Apparatus as claimed in Claim 11, wherein the further brake is of the multi-disc type, the elements carried by the input shaft being the discs, with the pads carried by a normally stationary member.

13. Apparatus as claimed in Claim 12, wherein the normally stationary member is constituted as a worm wheel in mesh with a worm, the latter being drivable at relatively slow speed by an auxiliary motor.

14. Apparatus as claimed in Claim 13, wherein the auxiliary motor is of the hydraulic type.

1 5. Apparatus as claimed in Claim 3, wherein the brake is hydraulically operated.

1 6. Apparatus as claimed in Claim 11, wherein the further brake is hydraulically operated.

1 7. Power transmission apparatus substantially as hereinbefore described with reference to the accompanying drawing.

18. A gearbox provided with power transmission apparatus as defined in any preceding Claim.

1 9. A gearbox substantially as hereinbefore described with reference to the accompanying drawing.

20. A scraper chain conveyor provided with a gearbox as defined above.

21. A scraper chain conveyor substantially as hereinbefore described with reference to the accompanying drawing.