GB1573302A

GB1573302A - Conveying systems u

Info

Publication number: GB1573302A
Application number: GB139976A
Authority: GB
Original assignee: Carrier Drysys Ltd
Current assignee: Carrier Drysys Ltd
Priority date: 1977-02-14
Filing date: 1977-02-14
Publication date: 1980-08-20

Description

(54) IMPROVEMENTS IN CONVEYING SYSTEMS (71) We, CARRIER DRYSYS LI MITED, A British Company, of Carrier House, Warwick Row, London, SW1E 5EL, England, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to conveying systems, and more particularly to overhead track conveying systems.

The term "overhead track conveying system" is used herein to indicate a conveying system in which the load to be carried is normally suspended beneath the conveying track. It does not necessarily indicate that the track is above ground level.

While satisfactory for certain applications, known overhead conveying systems, such as chain conveyors, do not share the degree of flexibility inherent in conveying systems in which the load is carried on top of the conveying track. Despite their flexibility however these latter systems do suffer from disadvantages for certain applications, and it is an object of the invention to provide an overhead conveying system which has the same degree of adaptability of these systems with a minimum of the disadvantages of known overhead systems.

According to the present invention, there is provided a conveying system including a conveying track comprising a series of juxtaposed rollers, and a movable load-carrying member supported by the rollers for rolling movement therealong, the load-carrying member being adapted to carry a load beneath the conveying track.

The load-carrying member suitably comprises an elongate skid adapted for rolling contact with the rollers, and hanger means mounted on the skid for carrying a load beneath the conveying track.

The skid can be formed from any suitable shaped-section material and the rollers are preferably profiled in axial cross-section to locate the skid axially thereon. For example, in a preferred embodiment of the invention, the skid is formed from a length of circular-section tubular material and the rollers taper inwardly from each end to form a central groove which receives the skid.

Other arrangements are feasible, such as a skid formed from square-section tube received in a groove formed in cylindrical rollers or concave rollers which locate a skid of semi-circular shaped section.

The hanger means for the load-carrying member may comprise any suitable single or multiple suspension having a device such as a hook for connection to a load; in the preferred embodiment, the hanger means comprises a pair of spaced brackets connected to the skid and spaced from the opposite ends thereof. Each bracket includes a beam member extending transversely beneath the skid which is provided with load attachment points. Suitably, each bracket is of substantially inverted U-shape and has one arm shorter than the other, the end of the shorter arm being connected to the upper surface of the skid member and the end of the longer arm being connected to the upper surface of the beam member.

This arrangement allows the brackets sufficient clearance around the ends of the rollers in the conveying track. The configuration of the hanger means is such that the load-carrying member balances correctly on the rollers with the beam members lying in a generally horizontal plane beneath the skid.

Preferably two load attachment points are provided on each beam member, so that where two brackets are provided, a fourpoint suspension is achieved. The position and number of the load attachment points can be varied to suit the nature of the loads to be carried.

The conveying system according to the invention preferably includes drive means for driving the movable load-carrying member around the conveying track. These drive means may be fitted either to the conveying track or to individual load-carrying members.

In the preferred arrangement, in which the drive means are fitted to the conveying track, these are suitably adapted to rotate some or all of the rollers; these driven rollers are thus capable of frictionally driving a load-carrying member around the system. In the particular embodiment described, the shaped surfaces of the rollers co-operate with the skid to provide a proper rolling and friction driving path for the skid.

While the conveying track may comprise a continuous series of rollers mounted in any suitable support, in a particularly advantageous embodiment of the invention, the conveying track comprises one or more individually powered track sections which suitably comprise beams having rollers journalled at intervals along one side thereof in suitable bearings mounted in the walls. The track sections may be of standard, predetermined length or may be manufactured to any desired length to suit the plant for which the system is designed. Some or all of the rollers are provided with powered axles having chain sprockets at their free ends, and the drive means for each length of track suitably comprises an electric motor mounted on the hollow section adapted to drive the rollers through an endless chain extending over the sprockets.In an alternative embodiment, individual chains are used to drive all or a selected number of the rollers of each section.

The lengths of individual track sections are just sufficient to accommodate one load-carrying member, and these track sections may be laid end-to-end to provide an extended or endless path for the loadcarrying members.

It is not essential for every track section to be individually powered, and indeed it may be necessary in some systems for some sections to include only idler rollers. This might be the case, for example, where the conveying track is downwardly inclined and the load-carrying members can move freely over it without drive means.

The arrangement of individually powered lengths of track section allows the conveyor system to be arranged such that power is fed to a section only when movement of a load-carrying member over that section is required. This is achieved by control means enabling sequential switching of the drive means for the track sections as a loadcarrying member passes around the conveying track. The control means is suitably activated by sensors provided either on the conveying track or on the load-carrying members themselves, or both. These sensors may comprise for example proximity switches, pneumatic switches, mechanically operated switches, or light-sensitive cells.

The arrangement whereby power is fed to a section only as a load-carrying member approaches and passes over that section has substantial advantages over e.g. a continuously operating chain conveyor, particularly as regards noise, pollution and power consumption.

Advantageously, the free ends of the skid are shaped to facilitate smooth transfer over the rollers, for example they may be tapered or upwardly-inclined, and in addition the ends may be provided with buffers so that they can contact fixed stops or other loadcarrying members travelling around the system without damage. Each load-carrying member may also be provided with one or more upwardly-extending stirrups which act as connections for hooks of a conventional overhead chain conveyor system; these stirrups are suitably located on the uPper surfaces of the brackets. The ability of the load-carrying member to be transferred onto a conventional chain conveyor substantially increases the flexibility of the system according to the invention.

The arrangement of individually powered track sections means that loads can be moved around the system over different sections at different speeds. Where required, the sections may be made individually movable to provide the system with great flexibility. For example, one track section may be mounted on a liftable and lowerable support to enable a load on that section to be moved from one length of conveying track to another length of track at a different height. In another embodiment, a track section may be movable in a horizontal plane to allow communication of loads between a single track section and two or more other sections which it serves. Further examples of such modified track sections which can be achieved with a system according to the present invention will be found in the description which follows hereinafter.

As stated, it is envisaged that the drive means for the load-carrying members could be mounted on the members themselves.

This could be achieved for example by the use of a linear induction motor the "armature" of which is mounted on the loadcarrying member and the field coils of which are arranged along individual track sections.

Alternatively, the field coils may be mounted on the load-carrying member and the individual track section provided with a continuous length of metal flange material acting as the armature.

In order that the invention may be more fully understood, embodiments in accordance therewith will now be described by way of example with reference to the accom panying drawings in which: Figure 1 shows a perspective view of a load-carrying member for use in a conveying system according to the invention; Figure 2 shows a perspective view of a length of track section; Figure 3 shows a perspective view of part of a conveying system showing a liftable and lowerable track section; Figure 4 shows a perspective view of part of a conveying system which is provided with a liftable and lowerable track section similar to that shown in Figure 3, but which is additionally rotatable about a horizontal axis; Figure 5 shows a perspective view of part of a conveying system illustrating a horizontally movable track section;; Figure 6 shows a vertical sectional view through part of a conveying system according to the invention passing through a paint drying oven; Figure 7 shows a view similar to that shown in Figure 6 with the system passing through a paint spraying booth and illustrating a different arrangement of drive means for the conveying system; Figure 8 is a diagrammatic elevation view showing an arrangement for transferring loads carried by a conveying system according to the invention onto a conventional chain conveyor.

Figure 9 is a vertical cross-sectional view of a section of conveying track used in the arrangement of Figure 8 but incorporating a minor modification; and Figure 10 shows two views of a modified arrangement of skid and hanger adapted for longitudinal and transverse movements.

Referring to the drawing, Figures 1 and 2 show the basic elements for an overhead conveying system adapted for transporting loads such as vehicle bodies around e.g. a paint finishing plant. These elements comprise a load-carrying member 10 (Figure 1), and a track section 12 (Figure 2).

The load-carrying member 10 comprises a skid 15 formed from a single length of tubular steel of approximately 5.5 m length.

Hanger means for connecting a load to the skid are provided and comprise a pair of generally U-shaped brackets 16 each of which terminate in a transverse beam 17 of tubular steel material located below the skid 15. The brackets 16 are formed from plate material, and as will be seen from Figure 1, each bracket has one arm longer than the other with the shorter arm 18 welded at 19 to the upper surface of the skid. The longer arm 20 is welded at 21 to the upper surface of its corresponding beam 17, and the dimensions and positioning of the skid, the brackets and the beams are such that the load-carrying member will balance in the position shown in Figure 1 with the beams 17 located below the skid 15 in a horizontal plane.

Ears 22 are secured to the underside of the beams 17, and these are provided with holes 23 which form pickup points for a load. In this case the pickup points form a four-point suspension for a stirrup for a vehicle body (not shown). The upper ends of the brackets 16 are provided with eyes 25 which enable the load-carrying member 10 to be picked up by the hooks 26 of an overhead chain conveyor 27, the path of which is shown in broken lines in Figures 1.

The skid 15 of the load-carrying member 10 is received within the central groove of a series of double-tapered rollers 30 which together define the path along which the load-carrying member travels. These rollers comprise the conveying track for the system which in this case is made up of a series of the individually-powered track lengths 12 shown in Figure 2, these lengths being mounted end-to-end where the conveyor is to have a straight run. As will be seen from the cross-section of track shown in Figures 6 and 7, the central groove of the rollers cooperates with the outer surface of the skid 15 to provide a rolling and friction driving surface for individual load-carrying members. The rollers may be made of any suitable material such as metal or plastics material.

The track length 12 shown in Figure 2 comprises a box-section supporting beam 32 of e.g. 6 m length to which is welded mounting brackets 33 by which the beam may be suspended from a supporting structure. The double tapered rollers 30 are equally spaced along the beam and are mounted on powered axles journalled in suitable bearings mounted in the walls of the box section, and these axles are provided with sprockets 34 over which passes an endless chain 35 maintained at the correct tension by tensioners 38. The chain 35 is driven through an electric brake motor 36 driving through a reduction gear box 37.

In the example shown in Figure 2, all the rollers in the track section are driven. In some applications however individual rollers only may be driven, and in circumstances where other means for moving the load-carrying member are provided, entire lengths of track may be undriven, the rollers acting as idler rollers only. For most applications however, powered track sections are required.

The direction of drive of the rollers is usually uni-directional but drive can be in either direction if required, and may be of fixed or variable speed. In addition, and by for example suitable arrangement of sprockets, some of the rollers in any one section may have a different speed from the others to assist for example in transfer between adjacent sections running at different speeds.

The length of each powered track section 12 is sufficient to accommodate completely a load-carrying member 10 and where track sections are aligned one behind the other, proximity switches or other suitable sensors are provided so that power is only applied to a section as a load approaches and passes over it. Other switches may be arranged to control the movement of load-carrying members around the system; for example control devices may be arranged to operate the drive means for a track section only when the track length immediately in front is free of a load-carrying member.

As will be apparent from Figure 1, the ends 28 of the skid 15 are shaped to allow smooth transfer of the skid over the grooved rollers of the track, and in addition these may be formed from a resilient material to act as buffers to prevent damage in the eventuality of contact with fixed stops or between two load-carrying members. In a further safety measure to prevent damage to loads such as car bodies mounted on the load-carrying members, the ends of the skid extend well beyond the position of the brackets 16 so that contact between loads cannot occur even if load-carrying members collide. Sensors may also be incorporated into the ends of the skids if required.

Although the track sections are primarily intended for straight-line movement of loads between horizontal set points, with suitable design of the rollers it is possible for a load-carrying member to negotiate limited inclines, declines and curves. The ability of a load-carrying member to negotiate curved sections can be improved by articulating the load-carrying member 10 in a horizontal plane into two or possibly more pivotally interconnected skids. In this case modification must be made to the hanger means for a load by pivotally mounting the brackets 16 on the respective skid 15 and providing a tie bar arrangement to maintain the beams 17 spaced and substantially parallel at all times.

Where downward or upward inclines are to be negotiated, the load-carrying member may be run onto a horizontal but inclinable track section which is then tilted for alignment with an inclined track section which may include free running idler rollers. In the case of a downward incline, the loadcarrying members may run freely down this section (providing that some form of speed control or braking means is employed).

With an upward incline, a booster drive may be added which engages the load-carrying member (for example by means of dogs or hooks engaging the brackets 16). The loadcarrying member may then run onto a section which can be moved into a horizontal position for final transfer of the member onto a fixed and level track section.

Figures 3, 4 and 5 illustrate various arrangements of movable track lengths which enable loads to be transferred between horizontally or vertically displaced sections of track.

In Figure 3, the movable track length 40 is mounted on the cantilevered arms 41 and 42 of a lifting frame 43 which is vertically displaceable in the direction of arrows 44.

The lifting frame is guided by means of vertical I-section guides 45 and rollers 46 and 47 which engage within the section 48.

The lifting frame 43 is suspended at 50 from a driving chain 49 which passes over the sprocket 51 and which is driven through a reduction gearbox by an electric brake motor (not shown), although the lifting frame may be operated hydraulically or pneumatically if required. The lifting frame may additionally be counterbalanced to conserve power.

Fixed stops 52 and 53 are provided on adjacent lengths of powered track 54 and 55 to ensure correct vertical location of the track length 40 in its uppermost position.

This arrangement enables the track length 40 to function as a lift section which can be used to transfer loads to one or more lower levels of conveyor track. It may be utilised for example to serve a series of superposed storage lines or simply to transfer loads from one track level to another. The control system for the lifting frame drive suitably includes devices which ensure the correct alignment of the track length 40 with the fixed sections.

Figure 4 shows a similar arrangement to that of Figure 3 but with the additional feature of the track section 58 being pivotable about a horizontal axis, i.e. in the direction of the arrows 59. This movement is used to effect for example drainage of the load after a paint-dipping operation.

In this embodiment the lifting frame 60 is, like the frame 43, movable along vertical guides in the direction of arrow 61, but has arms 62 which in this case terminate in a trunnion bearing 63. The track section 58 carries a tubular support 64 for an axle journalled in the bearing 63, and this support is provided with a crank arm 66. The piston rod 67 of a hydraulic or pneumatic cylinder 68 is pivotally attached to the crank arm 66, and the cylinder is in turn pivotally mounted to a support 69 fixed to an arm 62.

Activation of the hydraulic cylinder 68 causes a pivotal movement of the track section 58 about its horizontal axis, the direction of this pivotal movement depending on whether the piston rod 67 is pushed out of or retracted into the cylinder 68.

Rotation of the track section may also be carried out by an electro-magnetic thruster or a lead screw device.

In order to prevent a load-carrying member from running off the track section 58 during this pivotal movement, a locking device 70 is provided on the upper surface of the beam 57. This comprises a plate 71 pivotally mounted on the beam and movable by a pneumatic or hydraulic cylinder 72 between an open position shown in Figure 4 in which the plate lies substantially at right angles to the upper surface of the beam 57, and a locking position in which the plate lies substantially parallel to this upper surface.

In the locking position a slot 73 formed in the plate engages over the shorter arm 18 of one of the brackets 16 of a load-carrying member 10 to positively arrest the loadcarrying member on the track section.

The combination of lifting and tilting movements for the track section 58 is particularly useful in a paint dipping operation. In such an operation, a load-carrying member supporting for example a car body is driven onto the section 58 and locked in position by the locking device 70. The lifting frame is then operated to lower the body into the paint bath; after a predetermined interval, the track section is lifted and then rocked about its axis to drain the body of excess paint, the section is then raised to its uppermost position and the load-carrying member driven off onto the fixed conveyor track.

Figure 5 shows a track section 72 which is mounted as a travelling bridge section to effect transfer of a load between laterallydisplaced track sections, one of which is shown at 73.

The section 72 is provided with powered bogies 74 having wheels 75 which engage rails 76 formed by the lowermost flange of parallel I-section beams 77. The bogies are driven by geared electric brake motor units 78 which receive power from a conventional pick-up system. Other forms of drive means, such as a linear induction motor utilising the rail flange as the armature equivalent may be used for the bogies 74.

A powered locking device 80 is provided for effecting positive alignment of the movable bridge section with the fixed track section 73. This comprises a pivotal plate 81 which engages an indented lateral plate 82 mounted on the fixed section 73.

As stated, the travelling bridge section allows transfer of a load between laterallydisplaced storage lines. With suitable alterations however, a much greater range of movements can be achieved using the bridge section. For example, the bridge section may be constructed to enable both horizontal and vertical displacement of its associated track section to allow a large number of horizontally and vertically displaced storage lines to be served by the bridge section. The movements between lines may be computercontrolled to enable items to be recalled automatically from the storage lines.

More than one powered length of track section may be carried by the bogies 74, so that a tandem arrangement can be provided for supply of parallel fixed tracks. In addition, the track section may be mounted on a turntable on the bogies to allow rotary displacement of a load in a horizontal plane.

Such a turntable may also be provided independently of a bridge section.

Figure 6 shows a cross-section through a process compartment comprising a drying oven 84 through which vehicle bodies are carried on a conveying system according to the invention. The double-tapered or grooved rollers are shown at 85, a skid at 86, a hanger bracket at 87, a beam at 88 and the vehicle body stirrup at 89.

With such process booths, it is most important that the drive means for the conveyor system is separately housed in order to avoid damage from the hostile environment and to avoid contamination of the goods being carried. This is achieved in this embodiment by mounting the driving roller axle bearings 90 and sprockets 91, together with all the drive gear, within an insulated compartment 92; a suitable seal 93 is provided where the roller axle 94 passes through the wall of the compartment 92.

In this embodiment, the rollers are supported by beams 95 carried by the side walls and roof of the booth 84. In Figure 7, the compartment comprises a paint spraying booth 96. The booth is symmetrical internally, and the rollers are carried in bearings bolted to a beam 97 carried by the roof structure of the booth. In the Figure 7 embodiment, a tray 98 is provided beneath the rollers 99 to further ensure that no contamination of the booth takes place.

This is most important where e.g. car bodies are being painted. The separation of the conveyor drive from the booths in addition results in substantially lower servicing costs.

Figures 8 and 9 show an arrangement by which a load-carrying member travelling on an overhead track constructed in accordance with the invention can be transferred to or from a conventional chain conveyor.

In this construction, the load-carrying member 110 passed from a fixed length of track 112 onto a powered track section 113 which is suspended from links 114, 115 pivotally connected at one end to the section 113 and at the other end to fixed supports 116, 117 respectively. The link 114 is connected to a hydraulic cylinder arrangement 118 which, by retraction of its piston, can raise the track section 113 so that the eyes 125 of the load-carrying member 110 are moved into the path of the hooks 119 of a conventional overhead chain conveyor 120. These hooks then pick up the load-carrying member 110 with its load 121, and the powered track section 113 is then moved back to its position adjacent the section 112 ready for the next load. The speed of the loadcarrying member on the section 113 may be varied to assist transfer from or to the chain conveyor.

In the construction shown in Figure 9, an endless belt 123 extends around the rollers 122 of the track lengths 112 and 113 and the skid of the load-carrying member rests on the upper surface of this belt rather than on the upper surface of the rollers. This method of drive for the load-carrying members is an alternative to the friction drive of the rollers and the skid; for example in the track of which the section shown in Figure 8 forms a part, the load-carrying members are carried around the system on endless belts similar to the belt 123.

Other alternatives and variations are possible to the system according to the invention other than those already described. For example, the drive means for the loadcarrying members may be by a linear induction motor with the plate-like armature fixed to individual load-carrying members and the field windings fixed to the track sections. These may be required only at intervals, acting as "boosters" to propel loads around the system.

Where articulated, i.e. pivotally interconnected skids are provided, they may be fitted with modified brackets to permit the skids to rotate through 90" for the transverse travel of the load.

Such an arrangement is shown in Figure 10, where the load-carrying member 128 comprises two skids (one shown 130) pivotally mounted at opposite ends of a connecting link 131. Hangers (one shown 132) are also mounted on the connecting link at opposite ends. The left-hand drawing in Figure 10 shows the load-carrying member in its normal travel mode with the skids 130 extending parallel to the connecting link 131 and the hanger 132 suspending a load from the beam member 133, which extends at right angles to its associated skid.

In the right-hand drawing in Figure 10, the part of the track section which includes rollers 134 has rotated through 90 , at the same time turning skid 130 so that it lies normal to the connecting link 131. The hangers 132 are shaped as shown to clear the ends of the skids as they rotate, and these hangers remain in the same position relative to the connecting link. The rotation of the skids enables the load-carrying member to be moved of onto a double track for transverse storage of the goods. If required entire track sections may be mounted on turntables to allow a transverse change of direction for the load-carrying members.

WHAT WE CLAIM IS: 1. A conveying system including a conveying track comprising a series of juxtaposed rollers, and a movable load-carrying member supported by the rollers for rolling movement therealong, the load-carrying member being adapted to carry a load beneath the conveying track.

2. A conveying system as claimed in Claim 1, wherein said load-carrying member comprises an elongate skid adapted for rolling contact with said rollers, and hanger means mounted on said skid for carrying a load beneath the conveying track.

3. A conveying system as claimed in Claim 2, wherein the rollers are profiled in axial cross-section to locate the skid thereon.

4. A conveying system as claimed in Claim 3, wherein in axial cross-section the rollers taper inwardly from each end, and the skid comprises a length of circular section material.

5. A conveying system as claimed in any of Claims 2 to 4, wherein the hanger means comprises two spaced brackets mounted on the skid at points spaced from opposite free ends thereof, each bracket being provided with a beam member connected to the lower end thereof which beam member extends transversely beneath the skid and is provided with load attachment points.

6. A conveying system as claimed in Claim 5, wherein each bracket is of substantially inverted U-shape with one arm of the U-shape shorter than the other, the end of the shorter arm being connected to the upper surface of the skid and the end of the longer arm being connected to the beam member.

7. A conveying system as claimed in any of Claims 1 to 6, including drive means for driving the load-carrying member along the conveying track.

8. A conveying system as claimed in Claim 7, wherein said drive means comprises means for rotating some or all of said rollers, whereby said load-carrying member is driven along the conveying track by frictional engagement therewith.

9. A conveying system as claimed in Claim 8, wherein said conveying track comprises one or more lengths of track section each provided with a respective drive means.

10. A conveying system as claimed in Claim 9, wherein said track sections each comprise a beam having rollers journalled at intervals along one side thereof, and at least some of said rollers are provided with axles having chain sprockets at their free ends, and said drive means comprises an electric motor mounted on the beam adapted to drive said sprockets by means of an endless chain.

11. A conveying system as claimed in

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. with its load 121, and the powered track section 113 is then moved back to its position adjacent the section 112 ready for the next load. The speed of the loadcarrying member on the section 113 may be varied to assist transfer from or to the chain conveyor. In the construction shown in Figure 9, an endless belt 123 extends around the rollers 122 of the track lengths 112 and 113 and the skid of the load-carrying member rests on the upper surface of this belt rather than on the upper surface of the rollers. This method of drive for the load-carrying members is an alternative to the friction drive of the rollers and the skid; for example in the track of which the section shown in Figure 8 forms a part, the load-carrying members are carried around the system on endless belts similar to the belt 123. Other alternatives and variations are possible to the system according to the invention other than those already described. For example, the drive means for the loadcarrying members may be by a linear induction motor with the plate-like armature fixed to individual load-carrying members and the field windings fixed to the track sections. These may be required only at intervals, acting as "boosters" to propel loads around the system. Where articulated, i.e. pivotally interconnected skids are provided, they may be fitted with modified brackets to permit the skids to rotate through 90" for the transverse travel of the load. Such an arrangement is shown in Figure 10, where the load-carrying member 128 comprises two skids (one shown 130) pivotally mounted at opposite ends of a connecting link 131. Hangers (one shown 132) are also mounted on the connecting link at opposite ends. The left-hand drawing in Figure 10 shows the load-carrying member in its normal travel mode with the skids 130 extending parallel to the connecting link 131 and the hanger 132 suspending a load from the beam member 133, which extends at right angles to its associated skid. In the right-hand drawing in Figure 10, the part of the track section which includes rollers 134 has rotated through 90 , at the same time turning skid 130 so that it lies normal to the connecting link 131. The hangers 132 are shaped as shown to clear the ends of the skids as they rotate, and these hangers remain in the same position relative to the connecting link. The rotation of the skids enables the load-carrying member to be moved of onto a double track for transverse storage of the goods. If required entire track sections may be mounted on turntables to allow a transverse change of direction for the load-carrying members. WHAT WE CLAIM IS:

1. A conveying system including a conveying track comprising a series of juxtaposed rollers, and a movable load-carrying member supported by the rollers for rolling movement therealong, the load-carrying member being adapted to carry a load beneath the conveying track.

11. A conveying system as claimed in

Claim 9 or Claim 10, wherein said conveying track comprises a plurality of said track sections laid end-to-end providing an extended or endless path for said load-carrying member, and each track section is longer than or substantially the same length as said load-carrying member.

12. A conveying system as claimed in Claim 11, wherein control means are provided operable to activate the drive means of successive track sections sequentially as said load-carrying member passes over the track sections, said control means including sensing devices capable of sensing the position of the load-carrying member on the conveying track.

13. A conveying system as claimed in any of Claims 9 to 12, wherein said conveying track includes one or more lengths of unpowered track section.

14. A conveying system as claimed in any of Claims 9 to 13, wherein at last one of the track sections is individually movable.

15. A conveying system as claimed in Claim 14, wherein said movable track section is mounted on liftable and lowerable support means, and said conveying track comprises track sections at different levels, said movable track section being liftable and lowerable to connect individually with the ends of the track sections.

16. A conveying system as claimed in Claim 15, wherein said movable track section is in addition mounted for pivotal movement about a horizontal axis, and locking means are provided operable to engage said load-carrying member to prevent movement thereof during a pivotal movement of the track section.

17. A conveying system as claimed in Claim 14, wherein said movable track section is mounted on liftably and lowerably support means, and said support means is adapted to raise said track section so that a load-carrying member thereon can be engaged by a conventional overhead chain conveyor.

18. A conveying system as claimed in any of the preceding claims, wherein the or each load-carrying member is provided with one or more upwardly-extending stirrups adapted for connection to carrying hooks forming part of a conventional overhead chain conveyor.

19. A conveying system as claimed in Claim 14, wherein said movable track section is mounted on horizontally displaceable support means and said conveying track comprises track sections terminating at two or more points on the same level, said movable track section being displaceable to connect individually with the ends of said sections.

20. A conveying system as claimed in Claim 14, wherein said movable track sec tion is mounted on turntable means adapted to rotate the track section about a vertical axis.

21. A conveying system as claimed in Claim 1, wherein said load-carrying member comprises a pair of pivotally interconnected skids adapted for rolling contact with said rollers, and hanger means pivotally mounted on each said skid for carrying a load beneath the conveying track, each said hanger means including a beam member extending transversely beneath the respective skid, and tie bars being provided between the hanger means to retain said beam members in substantially mutually parallel positions.

22. A conveying system as claimed in any of the preceding claims, including a plurality of said load-carrying members.

23. A conveying system, substantally as hereinbefore described with reference to Figures 1 and 2 or Figure 1 and 2 as modified by Figures 3 to 10 of the accompanying drawings.