GB2084104A - Hoist beam with carriages which ore movable on an overhead track - Google Patents

Abstract

A hoist beam to be mounted on an overhead track has lifting devices at its opposite ends with the spacing apart being variable. Each lifting device includes a lifting chain (15) passing over a direction changing roller (16) and being coupled to an endless chain (10) which passes around a drivable chain wheel (21) and a direction changing change wheel. Independent drive means (25) comprising a motor (37) and a transmission (39) which locks against return movement may be provided for each endless chain (10) or a common drive and transmission may be used. The lifting chains (15) may each be coupled to a respective endless chain (10) or one endless chain may have two lifting chains (15) coupled thereto. <IMAGE>

Description

SPECIFICATION Hoist beam with carriages which are movable on an overhead track The invention relates to a hoist or lifting beam to be mounted by carriages so as to be movable on an overhead track, in particular, though not exclusively, for use in underground mining operations.

Most previously proposed hoist beams of this kind have at least two mechanically drivable lifting means, such as chains, which are each associated with a respective end of the hoist beam and which are movable in respect of their spacing apart by moving them longitudinally of the hoist beam, for moving a load. At their lower end each lifting means is provided with a load hook or other load suspension means for suspending a load or a container carrying a load. The lifting means are generally chains, for example calibrated link chains, and are referred to hereinater for convenience as "lifting chains" although it should be understood that this term is intended to include other similar means such as ropes, particularly wire ropes, or straps.

A drive for the lifting chains may comprise for example a rotationally driven chain drum or a winch apparatus.

Also known are drives using pressure fluid cylinders which extend parallel to the longitudinal extent of the hoist beam and which drive lifting chains directly or by way of rollers in the manner of pulley block devices. It is also known for the lifting chains to be driven by screw spindles which extend parallel to the longitudinal extent of the hoist beam and which are engaged with spindle nuts which, upon rotary movement of the spindles, move longitudinally of the hoist beam. The lifting chains are secured to the spindle nuts and each pass around a directionchanging roller, the chains being provided at the lower end with a load hook or load suspension means.

The known lifting chain drive arrangements suffer from a number of disadvantages, particularly in the case of greatly varying load hook spacings and where there are two lifting chains at each end of the hoist beam. In that case, it is not possible to use conventional chain drives with winches, in which the chain is wound onto a drum, for reasons of space.

When using pressure fluid cylinders or spindles as the drive for the lifting chains, the drive units occupy a relatively large amount of space, but the operating travel available is comparatively short. The result of this for example in the case of changes in load hook spacing is that a complicated conversion operation has to be carried out by fastening the lifting chains at a longer or shorter length, for example by changing the positions on the chains at which they are secured to the spindle nuts or by using a plurality of direction-changing rollers, this involving a considerable amount of work and therefore correspondingly long down times. In addition, the ends of the lifting chains which are free after shortening the length thereof possibly have to be stored in separate winding means, in order to avoid the risk of accident, and this gives rise to further work and cost.

According to the invention there is provided a hoist beam to be mounted by carriages so as to be movable on an overhead track and comprising at least two lifting devices each having a lifting chain guided over a respective direction-changing roller and provided with a load hook or other load suspension means, each of the devices being associated with a respective end of the hoist beam and the devices being variable in respect of the spacing apart of their load hooks longitudinally of the hoist beam, and drive means for the lifting devices, wherein the drive means includes at least one endless chain which extends around a drivable toothed chain wheel, parallel to the longitudinal axis of the hoist beam and around a direction-changing chain wheel, with the lifting chains of the lifting devices coupled to the endless chain or to a respective one of the endless chains.

Such a hoist beam can provide a relatively long working travel in respect of the lifting chains in order thereby to avoid hanging up the free ends of the lifting chains when altering the load hook spacing. It can have a space-saving and compact arrangement in respect of the drives and may include up to four independently actuable lifting chain drives in a constricted space in the hoist beam, without the drives impeding each other.

The drives can be simple in operation, uncomplicated and easy to maintain, and thereby suited to the rough working conditions encountered in underground operation.

The arrangement of an endless chain drive can have the advantages over both the known winchtype construction and also over stroke-movement cylinders or operating spindles, that the working travel of the lifting chains can correspond at least to the total extended length of the endless chain. When the two chain heels are designed with correspondingly high edges on the chain wheel rims, an even longer operating travel can possibly be made available, by winding the lifting chains around the chain wheels. This advantageously has the result that, even when there is a relatively small distance between the chain wheels and therefore the endless chain is of correspondingly short overall length, the operating travel of the lifting chain can be relatively long for the operating conditions of the hoist beam.

Two endless chains with their loops disposed end-to-end can be provided within the longitudinal extent of the hoist beam. This simple arrangement permits the left-hand or right-hand lifting chain to be raised or lowered independently as desired, whereby a load can be simply raised and lowered or tilted about an axis which extends transversely with respect to the longitudinal extent of the hoist beam.

Alternatively, two endless chains with their loops disposed side-by-side can be provided within the longitudinal extent of the hoist beam. Similarly as in the case of endless chains which have their loops disposed end-to-end, this arrangement gives the advantageous possibility of not only raising and lowering a load but also tilting it about an axis which extends transversely with respect to the longitudinal axis of the hoist beam.

Four endless chains can be disposed in respective pairs, with their loops disposed end-to-end and side-by-side. This arrangement which particularly emphasisesthe advantages of the invention, can be an uncomplicated way of affording the possibility of not only raising and lowering the load by suitably raising or lowering the individual lifting chains, but also tilting a load about an axis which extends transversely with respect to the longitudinal axis of the hoist beam, and about an axis which extends parallel to the longitudinal axis of the hoist beam.

Accordingly, this construction makes it possible for a suspended load to be moved into virtually any desired position.

When there is a single endless chain or two endless chains which are disposed with their loops end-to-end, the axes of the chain wheels are preferably arranged vertically, while when the chains are disposed with their loops side-by-side, the chain wheel axes are preferably arranged horizontally.

The various alternative possibilities advantageously permit a skilled man in the artto design and arrange the drive means selectively in the manner which best complies with the respective requirements in each individual situation. Thus for example, when the chain wheel axes are in a vertical position, the amount of space occupied by the endless chain is at a minimum in the height direction, which can be of advantage in a particular situation.

The endless chain can be formed as an open-link or flat-link chain with the drivable chain wheel appropriately toothed. A simple open-link chain has the advantage that it is capable of withstanding the loadings imposed by operation under rough conditions, virtually without maintenance, and represents an inexpensive and well-proven component, while a fiat-link chain is advantageously available for very high loadings, while being of relatively low inherent weight, at the expense of somewhat higher maintenance cost.

The direction-changing chain wheel can be provided with a preferably spring-loaded tensioning means. A tensioning means of this kind can serve advantageously not only for compensating for changes in length of the endless chain, which are caused by wear, but it also serves likewise for damping any shock loadings that may occur in the entire hoist beam, and is advantageous for that reason.

In order to be able to move the load in any desired direction, it is advantageous for the endless chains to be provided each with an individual drive and to be drivable individually, in pairs or in other desired groupings.

Braking means or locking means can be associated with each drive means, to block the drive in the unactuated condition and automatically to be taken out of action when the drive means is set in operation.

This can also be achieved in a very simple manner for example by a self-locking transmission, for example a worm gear transmission, being arranged between the drive motor and the drive chain wheel, as is known per se.

In another advantageous embodiment, there is provided a control block from which the functions of the chain drives are centrally controllable. Thus a drive system for at least two endless chains may comprise a compressed air motor coupled to a hydraulic pump as a central drive assembly and an individual drive unit, including a hydraulic motor with transmission block and the drivable chain wheel, for each endless chain, together with the corresponding actuating and control members.

In order to comply with safety requirements, safety limit switches may be provided which1 in operative combination with the endless chains and/ or the lifting chains, and with the control block (if provided), prevent a predetermined working travel being exceeded, by switching off the drives.

To produce a synchronous lifting or lowering movement of the two load hooks in the same direction, the lifting chains can be coupled one to each of the oppositely directed runs of the endless chain, and are guided in opposite directions each to extend over its respective direction-changing roller.

In this simplest kind of arrangement therefore, a load can be raised and lowered with a single endless chain and two lifting chains.

To produce synchronous lifting or lowering movement of the two load hooks in opposite directions, the lifting chains can be coupled to one and the same run of the endless chain and are guided in opposite directions each to extend over its respective direction-changing roller.

A man skilled in the art can thus combine sets or cycles of motions, as he freely choses.

For the purposes of tilting a load our a load container, two pairs of lifting chains which are each associated with a respective end of the hoist beam and with respective endlessd chains can be connected to form traction means runs or lines which are laid around approximately arcuate guide means which are associated with the load and the radius centre point of which is disposed approximately in the region of the centre of gravity of the load.

This arrangement gives advantages in particular when the hoist beam is provided with four endless chains which are preferably arranged in respective pairs, one side-by-side and one end-to-end, and, when the hoist beam is provided with endless chains that can be driven individually, in pairs or in any desired groupings, whereby a load can be moved into any desired position.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which: Figure 1 shows a side view of one embodiment of a hoist beam according to the invention; Figure 2 shows a side view of a part of an endless chain with individual drive of the hoist beam of Figure 1; Figure 3 shows a plan view of an endless chain with a lifting chain secured thereto, in accordance with the invention, Figure 4 shows a plan view of another embodiment of a hoist beam according to the invention and having four endless chains; and Figure 5 shows a block circuit diagram of a drive system for four endless chains with a central drive unit and individual drive units for a hoist beam according to another embodiment of the invention.

Referring to the drawings, a hoist beam comprises a plurality of longitudinal webs 1,2,3 and 4 which are disposed in spaced parallel relationship to one another and are connected together in their upper regions by plates 5 and by a plurality of cross members 6 and 6' to form a substantially downwardly open box profile. Carriages 8 and 8' which are movable on an overhead rail 9 are pivotally mounted on the cross members 6 and 6', by means of connector pins 7 and 7'. The beam is thus suspended below the overhead rail 9 and can be moved along the overhead rail 9.

In the embodiment illustrated in Figure 1, the hoist beam is provided with four endless chains 10, 11, 12 and 13 which each have side portions of the loops which they form extending parallel to the longitudinal extent of the hoist beam. In the embodiment illustrated in Figure 4, the endless chains 10to 13 are positioned in pairs 10,11 and 12, 13 with the chains of each pair side-by-side and end-to-end with the other pair. Traction means in the form of lifting chains 15 and 15' are secured to the endless chains 10 to 13 by means of shackles 14 or like chain fasteners, and pass over direction-changing rollers 16,17,18 and 19 so that their free ends hang downwardly.Secured to each of the free ends of the lifting chains 15, 15' are respective lifting hooks 20 and 20' which are preferably rotationally movable, as is conventional in hoisting apparatus. However, other load suspension means of transportation containers suitable for transporting bulk or loose materials could be secured to the downwardly hanging ends of the lifting chains 15 and 15', if desired. The endless chains 10 to 13 pass around drivable toothed chain wheels 21,22,23 and 24 and are in form-locking or other non-slip arrangement therewith.The drivable chain wheels 21 to 24 can be driven by motor transmission units, which can comprise individual drives 25, 25'; 26, 26' for each endless chain 10 to 13 as shown in Fiure 5, or for example a central common drive block for all chains, as is indicated in Figure 4 by a group transmission assembly 27 with a single compressed air motor 28 with clutch means and braking means for the individual drivable chain wheels 21 to 24.

Each endless chain 21 to 24 also passes around a respective direction-changing wheel 29,30, 31 and 32 biassed away from the respective chain wheel 21 to 24 by tensioning means 33, 34, 35 and 36, for example strong springs with adjusting members (not shown), whereby a suitable resiliency effect of varying degrees of hardness can be obtained.

The individual drives 25, 25'; 26, 26' may comprise motors 37,37'; 38,38' (Figures 1,2 and 5) which drive transmission assemblies 39,39'; 51, 51' interposed between the motors 37, 37'; 38,38' and the respective toothed chain wheels 21 to 24. The transmission assemblies 39,39'; 51,51' are selflocking worm gear transmission assemblies.

In the embodiment of Figure 4, the motor 28 drives all four chain wheels 21 to 24 by way of the group transmission assembly 27 and a central transmission unit 39" which is provided with automatically operating braking means or locking means (not shown) whereby, when the motor 28 is stopped, return motion of the endless chains 10 to 13 and thus downward movement of the load is prevented. To permit individual drives, the central transmission unit 39 is so arranged that the endless chains 10 to 13 can be driven individually, in pairs or in any desired grouping. Provided for control purposes is a central control block 40 which includes the necessary control and switching members and which is provided with an operating panel 41, by means of which movements of the lifting chains 15 and 15' can be controlled.

The panel 41 includes switching knobs or buttons 42 for the individual 'LIFT' and 'LOWER' functions of an 'emergency off' knob or button 43.

The motors 37,37'; 38,38' can be compressed air motors but the drive system shown in Figure 5 represents a further development wherein a central compressed air motor 44 drives a hydraulic pump 45 flange-connected thereto. The pump 45 supplies a switching and control unit 46 from which a system of hydraulic lines 47,47'; 48,48' leads to the individual motors 37,37'; 38,38' provided as hydraulic motors.

The central control block 40 is connected to the switching and control unit 46 by a cable 49 and is in turn connected to the panel 41 by an actuating cable 50. Safety limit switches 52 and 52' ensure that the arrangement is prevented from exceeding predetermined operating travel movements, whether in respect of the endless chains 10 to 13 or the lifting chains 15 and 15', the limit switches, upon operation thereof, intervening into the control assembly in such a way that all drives are switched off and braking means or locking means are switched on.

The chain wheels 16, 17, 18 and 19 are, as indicated in Figures 1 and 2, each movable in position in directions longitudinally of the beam by engaging the spindle of the chain wheel in a selected one of a plurality of mounting recesses provided at spaced apart positions longitudinally of the beam.

Claims (16)

1. A hoist beam to be mounted by carriages so as to be movable on an overhead track and comprising at least two lifting devices each having a lifting chain guided over a respective direction-changing roller and provided with a load hook or other load suspension means, each of the devices being associated with a respective end of the hoist beam and the devices being variable in respect of the spacing apart of their load hooks longitudinally of the hoist beam, and drive means for the lifting devices, wherein the drive means includes at least one endless chain which extends around a drivable toothed chain wheel, parallel to the longitudinal axis of the hoist beam and around a direction-changing chain wheel, with the lifting chains of the lifting devices coupled to the endless chain or to a respective one of the endless chains.

2. A hoist beam according to claim 1, in which there are two endless chains with their loops disposed end-to-end within the longitudinal extent of the hoist beam.

3. A hoist beam according to claim 1, in which there are two endless chains with their loops disposed side-by-side within the longitudinal extent of the hoist beam.

4. A hoist beam according to any one of claims 1 to 3, in which there are four endless chains with their loops disposed in respective pairs end-to-end and side-by-side.

5. A hoist beam according to any one of claims 1 to 4, in which when there is a single endless chain or two endless chains disposed with their loops end-toend, the axes of the chain wheels are disposed vertically, and when there are endless chains with their loops disposed side-by-side the axes of the chain wheel are disposed horizontally.

6. A hoist beam according to any one of claims 1 to 5, in which the endless chains are open-link or flat-link chains and the drivable chain wheels are appropriately toothed.

7. A hoist beam according to any one of claims 1 to 6, in which the or each direction-changing chain wheel is acted upon bytensioning means which tension the or the respective endless chain.

8. A hoist beam according to any one of claims 1 to 7, in which the endless chains are drivable individually, in pairs or in other desired groupings, and are each provided with an individual drive.

9. A hoist beam according to any one of claims 1 to 8, including associated with each drive means braking means or locking means which blocks the drive in the unactuated condition, and which is automatically taken out of action when the drive means is set in operation.

10. A hoist beam according to any one of claims 1 to 9, including a control block from which the functions of the drive means are centrally controllable.

11. A hoist beam according to any one of claims 1 to 10, including a drive system for at least two endless chains, comprising a compressed air motor which is coupled to a hydraulic pump to form a central drive assembly, and an individual drive unit, including a hydraulic motor with transmission block and the drivable chain wheel for each endless chain together with the corresponding actuating and control members and safety devices.

12. A hoist beam according to any one of claims 1 to 11, including safety limit switches which, in operative combination with the endless chains and/ or the lifting chain prevent a predetermined working travel being exceeded by switching off the drive means.

13. A hoist beam according to claim 1, in which, to produce a synchronous lifting or lowering movement of the two load hooks in the same direction, the lifting chains are coupled one to each of the oppositely directed runs of the endless chain and are guided in opposite directions each to extend over its respective direction-changing roller.

14. A hoist beam according to claim 1, in which, to produce a synchronous lifting or lowering move mentofthetwo load hooks in opposite directions, the lifting chains are coupled to one and the same run of the endless chain and are guided in opposite directions each to extend over its respective direction-changing roller.

15. A hoist beam according to one of claims 1 to 14, for the purposes of tilting a load or a load container, two pairs of lifting chains which are each associated with a respective end of the hoist beam and respective endless chains are connected to form traction means runs or lines which are laid around approximately arcuate guide means which are associated with the load and the radius centre point of which is disposed approximately in the region of she centre of gravity of the load.

16. A hoist beam substantially as hereinbefore described and illustrated with reference to the accompanying drawings.