GB2368623A

GB2368623A - Chain

Info

Publication number: GB2368623A
Application number: GB0026100A
Authority: GB
Inventors: Andrew Raymond Stone; Gary William Bromham
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-10-25
Filing date: 2000-10-25
Publication date: 2002-05-08
Also published as: GB0026100D0; WO2002035115A1; AU2001292115A1

Abstract

A chain having a link comprising a pair of mutually spaced side plates 16,17 removably mounted on opposite sides of a pair of elongate members 18,19 which are driven by a sprocket, in use. The elongate members 18,19 extend through the side plates 16,17 which are restrained against movement by removable fastening means, e.g. circlips 20. The chain may also comprise a bush 21 having a non-circular cross-section 22a to prevent rotation.

Description

CHAINS DESCRIPTION Technical Field This invention relates to chains and in particular to sprocket-drivable chains of the kind comprising an endless loop of interconnected links engaged by a sprocket drive wheel.

Background Art Conventionally, sprocket-drivable chains of the said kind are produced as a linear sequence of links. Each link comprises a pair of rods extending in parallel spaced-apart relation between a pair of side plates, end portions of the side plates of adjacent links overlap one another (either inwardly or outwardly), and the rods extend between these overlapping ends such that each rod has four side plate portions associated with it.

Generally, the two rods of each link are permanently and irremovably connected (e. g. as by welding) to one or both of the side plates.

To form a loop of desired dimensions, a suitable length is"cut"or detached from off the linear sequence of chain links, and the two ends of this length are then connected to one another by a special ends-connecting link.

If any other link of the chain becomes worn or damaged during-use, then the entire endless chain needs to be replaced-even if the damage or wear is to just one or two specific links (other than the end-connecting link). This is wasteful and gives rise to unnecessary maintenance expense.

Accordingly it is considered desirable to provide a sprocket-drivable chain of the said kind, and links therefor, that can avoid the above-mentioned and/or other disadvantages of the prior art.

Summary of the Invention According to a first aspect of this invention there is provided a link for a sprocketdrivable link chain of the said kind, the link comprising a pair of side plates mounted in mutually spaced-apart relation at the opposite ends of a pair of rods extending therethrough, the plates being restrained against movement apart by fastening means - preferably removable fastening means, e. g. circlip means-engaging the protruding ends of the rods.

Operation of the (removable) fastening means (to release said restraint) permits the two side plates and the two rods to be all wholly separable from one another.

Preferably the circlip means comprises four circlips, one per rod-end.

Advantageously the rods are encompassed by sleeve-like bushes that are mounted nonrotatably in apertures provided in the side plates. For example, each bush end may be provided with a non-circular cross-section to engage an aperture of mating crosssection in the associated side plate. Conveniently this non-circular cross-section may be provided by a flat portion in an otherwise arcuate perimeter of the bush end.

According to a second aspect of this invention there is provided a link for a sprocketdrivable link chain of the said kind, the link comprising a pair of mutually spaced-apart side plates removably mounted in mutually spaced relation on the opposite ends of a pair of elongate members in use drivable by a said sprocket.

Preferably said elongate members comprise sleeve-like bushes mounted non-rotatably in apertures provided in the side plates. For example, each bush end may be provided

with a non-circular cross-section to engage an aperture mating cross-section in the associated side plate. Conveniently this non-circular cross-section may be provided by a flat portion in an otherwise arcuate perimeter of the bush end.

According to the third aspect of this invention there is provided a sprocket-drivable chain of the said kind having every link thereof according to the said first or the said second aspect of this invention.

Brief Description of the Drawings By way of example, a sprocket-drivable chain of the said kind and according to the present invention will now be described with reference to the accompanying drawings of which: Figure 1 is a schematic perspective representation of part of one embodiment of this invention, and showing parts of one typical link (likewise according to the present invention) in separated out, exploded view; Figure 2 is a side view of a roller shown in Fig. 1 ; Figure 3 is a longitudinal cross-sectional view of a bush shown in Fig. 1; Figure 4 is a radial cross-sectional view of the bush shown in Fig. 3; and Figure 5 is a lateral elevation of a side plate shown in Fig. 1.

Detailed Description of Example (s) of the Invention Figure 1 shows five sequential links 11-15 of a sprocket-drivable chain 10 that are parts of an endless loop of interconnected such links so as to be sequentially and continuingly engaged by one or more sprocket drive wheels (not shown). All the links of the endless loop are identical to one another and each link is wholly separable into its individual constituent parts. To this end, each link-see in particular the separated out, exploded view of link 15-comprises a pair of side cheeks or side plates 16,17 mounted in mutually spaced-apart relation at the opposite ends of a pair of rods 18,19 that extend therethrough. The side plates 16,17 are restrained against movement apart by removable circlip means constituted (in this embodiment) by four individual circlips

20, one at each rod end. The circlips 20 engage in grooves 20a in the laterally protruding ends of the rods 18, 19 (Fig 2) and abut against the outwardly facing surfaces of side plates 16,17 to provide said restraint against movement apart of the side plates 16,17.

In one particularly preferred arrangement, the rods 18,19 are of EN24T steel, are 17.9mm in diameter and 60.5mm in length, with the circlip grooves 20a being 55.25mm apart and each 1.3mm wide with a depth diameter of 17. 0mm.

The illustrated rods 18,19 of this embodiment are encompassed by sleeve-like bushes 21 that are mounted non-rotatably in apertures 25 provided in the side plates 16,17.

For example, each bush 21 may be provided at each end with a non-circular crosssection to engage an aperture 25 of mating cross-section in the associated side plates 16,17. Conveniently (see Figs 3 and 4) this non-circular cross-section may be provided by a flat portion 22a in an otherwise arcuate perimeter band 22 of bush 21, this band 22 protruding as a step-down perimetral band from a shoulder 23 that abuts against the inward-facing surfaces of the respectively adjacent side plates 16,17. These shoulders 23 thereby serve to maintain a minimum set spacing between the pair of side plates 16,17 of the link. The aperture 25 is provided with a mating or corresponding "D"shape to accomodate fittingly the perimetral band 22 (see Fig 5).

In said one particularly preferred arrangement, for example, the bush 21 may be of like steel material with a through bore of 20. 0mm to receive a rod 18,19 therein. The bush of this particularly preferred arrangement is provided with a perimeter band 22 of nominal 23. 0mm diameter taken parallel to the flat portion 22a but a width of only

22. 3mm taken normal to the flat portion 22a. Preferably, in this arrangement, each end perimeter band 22 has a width of 5. 9mm and the distance between them (i. e. the unshouldered length of bush 21) is 31.25mm. The side plates 16,17 of this particularly preferred arrangement are preferably of 6mm thick EN43A steel, with the holes 25 at 50.5mm (or 2 inch) pitch or spacing between hole centres. The kidney-shape of the

side plates 16, 17 of this particularly preferred arrangement may be formed to provide a length of 91. 7mm (3. 61 inches) and a maximum width of 40. 9mm (1. 61 inches).

It will be apparent that each bush 21 of the illustrated embodiment extends between a pair of side plates 16,17 and this bush 21 encompasses a rod 18,19. Each tubular steel bush 21 is a so-called D-U bush and has a layer of bearing material on its cylindrical interior. This bearing layer within each bush 21 allows for relative arcuate motion between the bush 21 and the rotatably free rod 18 (or 19) that extends therethrough, and also allows for some lateral motion of the link itself relative to the sprocket (in a direction parallel to the sprocket's rotational axis) as each link in uses traverses around the chain's drive sprocket and/or along the chain's endless looped path.

Furthermore, to minimise clatter and other noise resulting in use inter alia from the metal-to-metal engagement between steel bushes 21 and the drive sprocket, each bush 21 may support an outer sleeve 27 of plastics material, e. g. a high density polythene (such as that known under the trade mark"PERPLAS"). It is generally these plastics material sleeves 27 that suffer the most wear and a need for replacement (and which, in the past, meant that the chain was irreparable and had to be entirely replaced).

In said one particularly preferred arrangement, the outer sleeve 27 of plastics material has a length of 31. 0mm and inner and outer diameters of respectively 24. 1mm and 29mm.

It will be appreciated that a linear sequence of interconnecting links (such as the illustrated links 11-15) can be produced of considerable length and, in accord with any particular requirement, a line of such interconnected links of appropriate predetermined length can be removed from the end of the linear sequence and that removed line then formed directly into an endless loop by fitting the side plates 16,17 from the end link at one extreme end of the line to the rods 18,19 of the end link at the other extreme end of the line. If any link of the thus-formed endless loop becomes worn or damaged

in use (e. g. by wear or damage to the outer plastics material sleeve 27), that one individual link can be readily replaced by removing the circlips 20 holding one side plate 16 or 17 in place, removing that side plate and replacing any damaged part before re-connecting the link parts to the remaining, and still utilisable, Jinks of the endless loop.

In a modification, only one of the plates (16 or 17) is provided with the D-shaped holes 25, the other side plate (17 or 16) being provided with a fully circular hole 25.

Optionally in that case, the associated end of the bush 21 may omit the flat 22a.

Other modifications and embodiments of the invention, which will be readily apparent to those skilled in this art, are to be deemed within the ambit and scope of the invention, and the particular embodiment (s) hereinbefore described may be varied in construction and detail, e. g. interchanging (where appropriate or desired) different features of each, without departing from the scope of the patent monopoly hereby sought. For example, one pair of rods 18,19 maybe extended laterally outwards of the chain 10-such as is shown for link 12-and these rod extensions 28,29 may have an arm or other fixture mounted thereto to provide a specific function (e. g. actuate a counter or other device) for each full revolution of the endless chain. Also, for example, the side plates 16,17 may be other than the usual"kidney"shape or"figure- of-eight"shape illustrated.

Claims

CLAIMS 1. A link for a sprocket-drivable link chain of the kind comprising an endless loop of interconnected links, the said link comprising a pair of side plates mounted in mutually spaced-apart relation at the opposite ends of a pair of rods extending therethrough, the plates being restrained against movement apart by fastening means engaging the protruding ends of the rods.
2. A link according to Claim 1, wherein said fastening means comprise removable fastening means.
3. A link according to Claim 2, wherein said removable fastening means comprises circlip means.
4. A link according to Claim 2 or Claim 3, wherein said removable fastening means comprises four circlips, one per rod end.
5. A link according to any one of the preceding Claims, wherein the rods are encompassed by sleeve-like bushes that are mounted non-rotatably in apertures provided in the side plates.
6. A link according to Claim 5, wherein at least one end of each bush is provided with a non-circular cross-section to engage an aperture of mating cross-section in the adjacent side plate.
7. A link according to Claim 5 or Claim 6, wherein each bush end is provided with a non-circular cross-section to engage an aperture of mating cross-section in the associated side plate.
8. A link according to Claim 7 wherein said non-circular cross-section is provided by a flat portion in an otherwise arcuate perimeter of the bush end.
9. A link for a sprocket-drivable link chain of the kind comprising an endless loop of interconnected links, the said link comprising a pair of mutually spaced-apart side plates removably mounted in mutually spaced relation on the opposite ends of a pair of elongate members in use drivable by a said sprocket.
10. A link according to Claim 9, wherein said elongate members comprise sleevelike bushes mounted non-rotatably in apertures provided in the side plates.
11. A link according to Claim 10, wherein at least one end of each bush is provided with a non-circular cross-section to engage an aperture of mating cross-section in the adjacent side plate.
12. A link according to Claim 10 or Claim 11, wherein each bush end is provided with a non-circular cross-section to engage an aperture of mating cross-section in the associated side plate.
13. A link according to Claim 12 wherein said non-circular cross-section is provided by a flat portion in an otherwise arcuate perimeter of the bush end.
14. A sprocket-drivable chain of the kind comprising an endless loop of interconnected links and having every link thereof according to any one of Claims 1 to 8.
15. A sprocket-drivable chain of the kind comprising an endless loop of interconnected links and having every link thereof according to any one of Claims 9 to 13.