GB1571498A

GB1571498A - Overhead conveyor systems

Info

Publication number: GB1571498A
Application number: GB2962676A
Authority: GB
Original assignee: Davies Pritchard & Richmond Lt
Current assignee: Davies Pritchard & Richmond Lt
Priority date: 1977-07-14
Filing date: 1977-07-14
Publication date: 1980-07-16

Description

(54) OVERHEAD CONVEYOR SYSTEMS (71) We. DAVIES PRITCHARD and RICHMOND Limited. British Company of Banks Lane. Liverpool Airport, Liverpool L24 8QR. 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 overhead conveyor systems of the kind in which load bearing trolleys running on a guide rail are driven there along by drive dogs carried by a drive means.One overhead conveyor system of the kind to which the invention is applicable is described in our prior Patent No. 1.373.759 and broadly comprises an overhead conveyor rail, trolleys supported by said rail each having a retractable dog, and drive means, e.g. a drive chain, from which project a succession of drive dogs for driving engagement with said retractable dogs of the trolleys.

Such systems frequently include, in addition to the main conveyor rail, a secondary rail or rails. e.g. leading to storage areas, onto which trolleys may be diverted by switch means. In such circumstances a secondary drive chain or chains is or are required carrying drive dogs for engaging the retractable dogs of the trolleys to maintain drive along the secondary rail. One of the difficulties of such a system is the necessity for maintaning drive at the switching points where it becomes necessary to disengage from the dogs of the main drive and pick up from the dogs of the secondary drive chain.

Conventionally this necessitates a careful synchronising of the speeds of the main and secondary drive chains and a matching of the pitch of the respective chains and drive dogs in order to avoid interference and possible damage to adjacently moving parts.

The present invention has for its object to simplify the switching arrangement and more particularly the chainge over from main drive to secondary drive whereby the need for synchronising speeds and matching chain pitches and drive dogs as referred to is obviated.

Broadly, according to the invention, an overhead conveyor system comprises load bearing trolleys running on a main guide rail being driven therealong by drive dogs carried by drive means, a secondary guide rail or rails onto which trolleys from the main guide rail may be diverted by switch means, secondary drive means carrying drive dogs to maintain drive along the secondary guide rail, wherein the trolleys of the system are connected in tandem assemblies of at least two, the first trolley (hereinafter usually referred to as a 'primary' trolley) of each assembly comprises a normally extended dog for being engaged by a drive dog of the main drive, and a second trolley (hereinafter usually referred to as a 'secondary' trolley) of the assembly has a normally retracted dog which is projectable for temporary engagement with a drive dog of the main drive chan when the primary trolley is disengaged from the main drive means by being switched from the main conveyor rail to a secondary conveyor rail, said normally retracted dog of the secondary trolley being displaceable vertically through the medium of one or more arms pivoted to the trolley and engaged with a spindle of the dog, said arm or arms carrying a roller or rollers which normally run on a flange of the main guide rail, and cam elements on said flange are located at a suitable distance (as dictated by the length of a trolley) before each switch point of the system and onto which cam elements said roller or rollers can run to cause operative displacement of the normally retracted drive dog.

By this means, drive to the trolley assembly is maintained during the switching of the assembly from the main conveyor rail to a secondary conveyor rail, and this without the need, as is usual, for matching the speeds of the various drive chains and the pitch of said chains and the drive dogs.

The invention is further described with the aid of the explanatory drawings accompanying the Provisional Specificalion which illustrate by way of example one embodiment.

In said drawings Figure I is a scheinitic plan view of part of an overhead conveyor system incorporating a secondary corivcyor rail.

Figure 2 is a lransverse sectional view of the main conveyor and drive drawn to an enlarged scale ns compared with the preceding view aud including a secondary trolley.

Figztr e 3 is an elevation depicting an assembly of two. primary and secondary, trollics connected in tandem.

Figtere 4 is an elevation of the secondary trolley showing schematically the mechanism for actuating its normally retracted dog.

Referring to snid drawings, A (Figure 1) generally denotes the main conveyor guide rail of an overhead conveyor system having a main drive chain B, and C a secondary or branch conveyor guide rail with a secondary drive chain 1). A switching tongue E is provided or diverting trolley assemblies from the main rail A to the secondary rail C.

The trolley assembly shown in Figure 3 comprises a primary (leading) trolley 10, and a secondary trolley 11. The two trolleys 10. 11 are connected by a load beam 12 from which loads to be conveyed can be suspended. Each trolley comprises at each side wheels or rollers 13 which are rotatable about transverse horizontal axes 14, and central wheels or rollers 15 rotatable about vertical axes. The guide rail A (as also the conveyor rail C) comprises two facing channel member 16 (Figure 2) the rollers 13 of the trolleys running on the internal lower flanges 16n of said channels and the rollers 15 running between the edges of said lower flanges 16a.The main driving chain B, (as also the secondary driving chain D) is suspended from and guided by an 'I' section rail 20 bv means of rollers 21 and carries at spaced intervals therealong driving dogs 22.

The primary trolley 10. comprises a retractable dog 17 for engaging with a drive dog 2' of a driving chain. and a flip dog 18 which prevents the trolley from overrunning the drive dog 22. A feeler 19 linked to the retractable dog 17 provides for the retraction of the dog 17 to disengage the drive when displaced upwardly, e.g. when engaging the ramped abuttment 23 of another trolley or a provided displaceable abuttment associated with the guide rail.

The secondary trolley 11 has no retractable driving dog as 17. but is provided with a normally retracted dog 24 which, being suitably guided, is displaceable vertically upwards from the position shown in full lines in Figures 4 to the position shown in broken lines. Upward movement of the dog 24 is effected through the medium of a pair (in this instance) of arms 25 which are pivoted one at each side of the trolley 11 on an axis 26. Said arms 25 have elongated apertures 27 at their ends remote from the axis 26 which apertures 27 are engaged with the ends of a spindle 28 of the dog 24. Each arm 25 carries on a stub shaft 29 a roller 30, said rollers normally running (as shown in Figure 2) on the upper flange 16b of the channels 16 which constitute the conveyor guide rail A (or C).Located at a suitable distance (as dictated by the length of a trolley assembly) before each switch point of the system on the upper flanges 16b of the guide rail A are cam elements 31 onto which the rollers 30 are arranged to run thereby to cause upward displacement of the dog 24 of a secondary trolley 11.

It will be seen that actuation of the switch tongue E to divert a trolley assembly from the main conveyor rail A to the rail C will cause the dog 17 of the primary trolley 10 to become disengaged from the drive dog 22 as it moves along the initial curve of the rail C.

At this time, the rollers 30 associated with the dog 24 of secondary trolley 11 run up and along the cam elements 31 whereby the dog 24 is projected upwardly to become drivingly engaged by a drive dog 22 of the main conveyor chain B. The trolley assembly is thus moved far enough along the secondary rail C for a dog 22 of the drive chain D to become engaged with the dog 17 of the primary trolley 10.

While the invention has been described more specifically in relation to trolley assemblies of two, the invention is not so restricted, as more than two trolleys may be included in an assembly, the essential fea ture being that one of the secondary trolleys includes a normally retracted dog which can be projected upwardly to take up and maintain drive to the assembly from the main drive chain until such time as the primary, i.e. leading, trolley is in a position to pick up drive from the drive chain of a secondary conveyor rail onto which the trolley assembly has been diverted.

WHAT WE CLAIM IS: 1. An overhead conveyor system comprising load bearing trolleys running on a main guide rail being driven therealong by drive dogs carried by drive means, and including a secondary guide rail onto which trolleys from the main guide rail may be diverted by switch means, secondary drive means carrying drive dogs being to maintain drive along the secondary guide rail, wherein the trollies of the system are connected in tandem assemblies of at least two, the

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. secondary conveyor rail, and this without the need, as is usual, for matching the speeds of the various drive chains and the pitch of said chains and the drive dogs. The invention is further described with the aid of the explanatory drawings accompanying the Provisional Specificalion which illustrate by way of example one embodiment. In said drawings Figure I is a scheinitic plan view of part of an overhead conveyor system incorporating a secondary corivcyor rail. Figure 2 is a lransverse sectional view of the main conveyor and drive drawn to an enlarged scale ns compared with the preceding view aud including a secondary trolley. Figztr e 3 is an elevation depicting an assembly of two. primary and secondary, trollics connected in tandem. Figtere 4 is an elevation of the secondary trolley showing schematically the mechanism for actuating its normally retracted dog. Referring to snid drawings, A (Figure 1) generally denotes the main conveyor guide rail of an overhead conveyor system having a main drive chain B, and C a secondary or branch conveyor guide rail with a secondary drive chain 1). A switching tongue E is provided or diverting trolley assemblies from the main rail A to the secondary rail C. The trolley assembly shown in Figure 3 comprises a primary (leading) trolley 10, and a secondary trolley 11. The two trolleys 10. 11 are connected by a load beam 12 from which loads to be conveyed can be suspended. Each trolley comprises at each side wheels or rollers 13 which are rotatable about transverse horizontal axes 14, and central wheels or rollers 15 rotatable about vertical axes. The guide rail A (as also the conveyor rail C) comprises two facing channel member 16 (Figure 2) the rollers 13 of the trolleys running on the internal lower flanges 16n of said channels and the rollers 15 running between the edges of said lower flanges 16a.The main driving chain B, (as also the secondary driving chain D) is suspended from and guided by an 'I' section rail 20 bv means of rollers 21 and carries at spaced intervals therealong driving dogs 22. The primary trolley 10. comprises a retractable dog 17 for engaging with a drive dog 2' of a driving chain. and a flip dog 18 which prevents the trolley from overrunning the drive dog 22. A feeler 19 linked to the retractable dog 17 provides for the retraction of the dog 17 to disengage the drive when displaced upwardly, e.g. when engaging the ramped abuttment 23 of another trolley or a provided displaceable abuttment associated with the guide rail. The secondary trolley 11 has no retractable driving dog as 17. but is provided with a normally retracted dog 24 which, being suitably guided, is displaceable vertically upwards from the position shown in full lines in Figures 4 to the position shown in broken lines. Upward movement of the dog 24 is effected through the medium of a pair (in this instance) of arms 25 which are pivoted one at each side of the trolley 11 on an axis 26. Said arms 25 have elongated apertures 27 at their ends remote from the axis 26 which apertures 27 are engaged with the ends of a spindle 28 of the dog 24. Each arm 25 carries on a stub shaft 29 a roller 30, said rollers normally running (as shown in Figure 2) on the upper flange 16b of the channels 16 which constitute the conveyor guide rail A (or C).Located at a suitable distance (as dictated by the length of a trolley assembly) before each switch point of the system on the upper flanges 16b of the guide rail A are cam elements 31 onto which the rollers 30 are arranged to run thereby to cause upward displacement of the dog 24 of a secondary trolley 11. It will be seen that actuation of the switch tongue E to divert a trolley assembly from the main conveyor rail A to the rail C will cause the dog 17 of the primary trolley 10 to become disengaged from the drive dog 22 as it moves along the initial curve of the rail C. At this time, the rollers 30 associated with the dog 24 of secondary trolley 11 run up and along the cam elements 31 whereby the dog 24 is projected upwardly to become drivingly engaged by a drive dog 22 of the main conveyor chain B. The trolley assembly is thus moved far enough along the secondary rail C for a dog 22 of the drive chain D to become engaged with the dog 17 of the primary trolley 10. While the invention has been described more specifically in relation to trolley assemblies of two, the invention is not so restricted, as more than two trolleys may be included in an assembly, the essential fea ture being that one of the secondary trolleys includes a normally retracted dog which can be projected upwardly to take up and maintain drive to the assembly from the main drive chain until such time as the primary, i.e. leading, trolley is in a position to pick up drive from the drive chain of a secondary conveyor rail onto which the trolley assembly has been diverted. WHAT WE CLAIM IS:

1. An overhead conveyor system comprising load bearing trolleys running on a main guide rail being driven therealong by drive dogs carried by drive means, and including a secondary guide rail onto which trolleys from the main guide rail may be diverted by switch means, secondary drive means carrying drive dogs being to maintain drive along the secondary guide rail, wherein the trollies of the system are connected in tandem assemblies of at least two, the

primary trolley of each trolley assembly comprises a normally extended dog for being engaged by a drive dog of the main drive, and a secondary trolley of the assembly has a normally retracted dog which is projectable for temporary engagement with a drive dog of the main drive when the primary trolley becomes disengagcd from the main drive means by being switched from the main guide rail to the secondary guide rail. said normally retracted drive dog of the secondary trolley being displaceable vertically through the medium of one or more arms pivoted to the trolley and engaged with a spindle of the dog, said arm or arms carrying a roller or rollers which normally run on a flange of the main guide rail, and cam elements on said flange are located at a suitable distance (as dictated by the length of a trolley) before each switch point of the system and onto which cam elements said roller or rollers can run to cause operative displacement of said nor mally retracted drive dog.

2. An overhead conveyor system, as claimed in claim 1, wherein the trollies of an assembly of trollies are connected by a load beam wherefrom loads to be conveyed are suspended.

3. An overhead conveyor system substantially as hercin described with reference to the drawings accompanying the Provisional Specification.