WO2009132400A1

WO2009132400A1 - An attachment apparatus for a choker chain

Info

Publication number: WO2009132400A1
Application number: PCT/AU2009/000551
Authority: WO
Inventors: Mark Andrew Stevens
Original assignee: Innovative Construction Techniques Pty Ltd
Priority date: 2008-05-02
Filing date: 2009-05-01
Publication date: 2009-11-05
Also published as: AU2008201955B1

Abstract

An attachment apparatus for a choker chain the apparatus including a body having at least one opening therethrough adapted to receive a portion of a chain, and a slide member, slidable relative to the body between a locking condition wherein the slide member engages a portion of the chain, locking in that portion relative to the body and a free condition wherein the slide member is free from the portion of the chain allowing the chain to move.

Description

AN ATTACHMENT APPARATUS FOR A CHOKER CHAIN Field of the Invention.

The present invention relates to choker chains such as those used by cranes to attach the load to the lifting cable. Background Art.

Choker chains are often used in conjunction with cranes and other heavy lifting apparatus to attach a load relative to the cable of the crane so that the load can be lifted.

There are other methods used to attach the choker chain to the load. Normally, the choker chain is attached at one end to the cable of the crane and the opposing end of the choker chain is provided with a hook which is passed under the load while the cable is slackened, and then attached through a link in the chain to secure the load. In this manner, the choker chain is normally attached directly to itself. Other mechanisms can be used such as passing a rod or bar through aligned links of chain once the chain has been passed about the load.

One problem with both of these methods is the lack of security in the attachment mechanism and also the difficulty in releasing the attachment mechanism as it once the crane applies the lifting force, the links of the choker chain tend to lock together and are difficult to release, especially if the load needs to be released quickly.

It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

Summary of the Invention. The present invention is directed to an attachment apparatus for a choker chain, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

With the foregoing in view, the present invention in one form, resides broadly in an attachment apparatus for a choker chain the apparatus including a body having at least one opening therethrough adapted to receive a portion of a chain, and a slide member, slidable relative to the body between a locking condition wherein the slide member engages a portion of the chain, locking in that portion relative to the body and a free condition wherein the slide member is free from the portion of the chain allowing the chain to move.

The attachment apparatus of the present invention is intended to provide a means by which a choker chain may be used and released, quickly and effectively, whilst providing a secure attachment for the chain. The attachment apparatus is adapted to be locked to an intermediate portion of the chain between the lifting mechanism and the free end of the chain, when not in use. This will assist in the location of the device and minimise the chance that the apparatus is lost or not conveniently at hand when required.

When in use, that is, when a load is to be lifted, the attachment apparatus is adapted to lock the free end of the chain and to allow the intermediate portion to move freely about the load, thereby creating the choker chain effect.

The attachment apparatus includes a body with at least one opening therethrough adapted to receive a portion of a chain. Normally, a pair of openings in the body will be provided. Preferably, the pair of openings will be spaced apart, and according to the most preferred embodiment, will be located at substantially opposite ends of the body. Typically, in use, the chain will extend downwardly through one of the openings, about the load, and then extend upwardly through the other of the openings.

According to the most preferred embodiment, the body includes a pair of parallel plate members attached to another in a spaced apart configuration. Normally, the plate members will be separated using spacing means. Typically, the plates will be connected/attached to one another using bolts (or any other suitable fastener). The spacing means will normally be or include rigid tubular members through which the connection/attachment bolts extend. Normally each end of the spacing means will abut an inner surface of each of the plate members. There may be other connection/attachment bolts provided in the apparatus without spacing members. Each of the plate members, also referred to as side plates, will typically be substantially T-shaped having a cross piece and a substantially perpendicular downcomer portion. The cross piece is typically substantially rectangular. In use, each cross piece will have an upper edge, a lower edge, and two end edges. Each cross piece of each side plate will preferably have a number of openings positioned such that the openings on respective side plates will be aligned in assembly. Preferably, each cross piece will have at least one, and normally a pair of guide openings to guide the slide member during movement thereof. Typically, one guide opening will be provided at each end of the cross piece. The guide openings will preferably be substantially in line and parallel with the upper edge of the cross piece. Each of the guide openings may be a slot opening where a slide plate is provided.

There will also typically be two pairs of openings extending through each cross piece, each pair located adjacent an end of the cross piece. Each of the openings will typically receive a fastener, normally a bolt with attendant spacing member and the respective bolts extending through each pair of bolt openings will typically define each of the chain openings for the chain.

The bolts extending through each of the openings in the side plates, in addition to attaching the side plates together and maintaining them in a spaced apart configuration, will also preferably act to guide the chain when extending through the opening in the body. For this purpose, the spacing members used to define the openings in the body member may have a different configuration from the spacing members is simply used to space the plates apart. For example, the spacing members used to define the openings in the body may include a plastic portion, and most preferably include a tubular metal core with a tubular plastic overlay.

Where slot openings are provided in each of the side plates, it is preferred that a terminal end of the slot will extend to a region which is at least partially between the bolts defining the opening in the body.

The cross piece preferably also includes a central opening located adjacent the lower edge of the cross piece. The central opening is preferably adapted to mount a pivot bolt. The cross piece will typically be provided with rounded corners in order to prevent or minimise injury to users of the apparatus. Each side plate also includes a downcomer portion. Normally, each downcomer portion will be substantially rectangular. Each downcomer portion will also preferably have at least one substantially central opening for mounting an abutment bolt. The downcomer portion may be manufactured separately from the cross piece and attached thereto, or may be integrally formed with the cross piece.

According to a preferred embodiment, a base member is provided and attached to the downcomer of one of the side plates. Preferably, the base member will extend substantially perpendicularly from the downcomer. The base member will typically protect the mechanism of the apparatus when the apparatus is assembled. There is typically an opening provided in the base member through which a quick release actuator means will extend.

The apparatus of the present invention includes a slide member or according to a preferred embodiment, normally a slide plate. Other slide members may be provided in the alternative such as a slidable rod or bar in order to engage openings in links of the chain in order to fix the links relative to one another.

According to a more preferred embodiment, the present invention resides in an attachment apparatus for a choker chain, the apparatus including a body with at least one opening therethrough adapted to receive a portion of a chain, and a slide plate having at least one slot adapted to at least partially obscure the at least one opening in the body, the slide plate slidable relative to the body between a locking condition wherein the at least one slot engages a portion of the chain, locking it relative to the body and a free condition wherein the at least one slot is free from the chain allowing the chain to move.

The plate will typically be an elongate plate, dimensioned such that when one opening of the body which is adapted to receive the chain, is obscured, the other of the openings will not be obscured. Therefore, the plate will typically be approximately equal in length to the cross piece of the body less the dimension of one of the openings.

The plate will normally have guide flanges extending laterally from the plate to be received in the guide openings in the side plates of the body. In use, the flanges will also transfer the load exerted on the chain, to the body. Preferably, at least two flanges are provided extending from each side each of the plate, one flange extending on either side, at either end of the slide plate.

Typically, the slide plate is provided with an opening, normally a slot, at either end. The opening is typically dimensioned to correspond to the thickness of a link in the chain. In use, adjacent links in the chain will normally abut either side of the slide plate when a link is located in the opening. Each of the openings is substantially U-shaped with the link in the chain received through the open end.

It is preferred that the slot openings provided in the slide plate are shaped differently. One of the slot openings will typically be a slot having substantially parallel sides. The other of the slot openings will preferably have a divergent opening, widening as the slot extends away from the other slot opening.

The divergent opening will preferably assist with the self-location of the chain during engagement. The base of the divergent opening (as opposed to the widest point) will preferably be approximately as wide as the parallel sided slot and approximate the thickness of the chain. The divergent opening is preferably oriented towards the intermediate portion of the chain with the parallel sided slot oriented towards the free end of the chain when using the device.

The U-shaped slots give the ends of the side plates a pair of spaced apart tongues. The bolts which define the openings through which the chain extends provide additional support to the slide plate and the ends of the tongues.

The slide plate normally also includes a central opening through which an actuation means, normally an actuation lever extends.

The slide member/plate is preferably movable such that when one portion of a chain extending through one of the openings, is locked relative to the body, the other opening and any chain extending therethrough, is free. The slide member/plate is movable from end to end relative to the body in order to lock only one portion of the chain relative to the body at any one time.

The apparatus also preferably includes an actuation mechanism in order to move and control the movement of the slide member. Normally, the actuation mechanism is sandwiched between the side plates of the body and in this manner is protected from accidental damage. Typically, the actuation mechanism includes an actuation lever, biasing means to bias the actuation lever into a particular position, and quick release means.

The actuation lever typically extends through the central opening in the slide plate. The actuation lever typically abuts the edges of the opening such that movement of the lever will move the slide plate. The actuation lever preferably has a pair of openings to receive pins or connectors, and an elongate slot in order to receive a pivot bolt. Normally, the slot extends parallel to the length of the lever in a position towards the lower end of the lever, with an opening positioned above the slot and the second opening positioned below the slot. Typically, the actuation lever extends downwardly into the body to a location between the downcomers of the side plates, and there abuts the abutment bolt which restricts movement of the actuation lever from end to end, thereby restricting movement of the slide plate.

The slot opening which receives the pivot bolt allows the actuation lever to be drawn in a direction perpendicular to the slide plate, to clear the abutment bolt, which then allows movement of the lever (and the slide plate) from end to end in order to operate the apparatus.

The actuation lever is preferably biased into the locking condition relative to one of the openings in the body adapted to receive the chain. The opening above the slot opening in the actuation lever preferably receives a connector used to connect resilient or biasing means, typically springs in order to bias the movement of the actuation lever. The biasing means may be connected or attached to the body or another component in order to provide the biasing effect. The opening located below the slot opening in the actuation lever is preferably used to connect the actuation lever to an over centre cam which is mounted for rotation about the abutment bolt. A quick release actuation means extending through the opening in the base member, preferably engages with the cam such that upon actuation of the quick release actuation means, the cam rotates, lifting the actuation lever above the abutment bolt and allowing movement of the actuation lever, typically under the biasing effect. The quick release actuation means may be remote or physically attached to the lever. For example, the quick release means may be a remotely actuable device which is operable for example from the cab of a vehicle.

According to the preferred embodiment, even in circumstances where the biasing means breaks and the biasing force on the actuation lever is lost, the quick release mechanism will typically not release the chain until determined movement of the lever is applied to clear the abutment bolt. A depression or similar provided in the edge of the lever into which the abutment bolt can rest may assist with this location. This increases the safety aspect of the device.

Normally, the actuation lever is biased to lock an intermediate portion of the chain.

Brief Description of the Drawings.

Various embodiments of the invention will be described with reference to the following drawings, in which:

Figure 1 is a front elevation view of an apparatus according to a preferred embodiment of the present invention with a chain in the "load attached condition".

Figure 2 is a view from above of the apparatus as illustrated in Figure 1.

Figure 3 is a front elevation view of an apparatus according to a preferred embodiment with a chain in the "load released condition".

Figure 4 is a view from above of the apparatus as illustrated in Figure 3.

Figure 5 is a schematic view of the components of an apparatus according to a preferred embodiment of the present invention. Figure 6 is a view from below of an apparatus according to a preferred embodiment of the present invention showing part of the mechanism.

Figure 7 is an alternative view from below of an apparatus according to a preferred embodiment also showing part of the mechanism.

Figure 8 is another alternative view from below of an apparatus according to a preferred embodiment also showing part of the mechanism.

Figure 9 is a view from above of the apparatus illustrated in Figure 3, with the chain removed. Figure 10 is a view from above of the apparatus illustrated in Figure 1, with the chain removed.

Detailed Description of the Preferred Embodiment.

According to a preferred embodiment of the present invention, an attachment apparatus for a choker chain.

The attachment apparatus 10 illustrated is referred to as a "quick release hitch" and includes a body 11 with a pair of chain openings 12 therethrough adapted to receive a portion of a chain 13. The body 11 mounts a slide plate 14 having a pair of slots 15 adapted to partially obscure one of the chain openings 12 in the body 11. The slide plate 14 is an elongate plate, dimensioned such that when one chain openings 12 of the body 11, is obscured, the other of the chain openings 12 will not be obscured such as is illustrated in Figures 9 and 10 in particular.

The slide plate 14 is slidable relative to the body 11 between a locking condition wherein one of the slots 15 in the slide plate 14 engages the chain 13, locking it relative to the body 11 and a free condition wherein the slot is free from the chain 13 allowing the chain 13 to move.

The quick release hitch illustrated is adapted to be locked to an intermediate portion 40 of the chain 13 between a lifting mechanism and the free end 41 of the chain 13, when not in use. This will assist in the location of the device and minimise the chance that the apparatus is lost or not convenient when required.

When in use, that is when a load is to be lifted, the quick release hitch is adapted to lock the free end of the chain 13 and to allow the intermediate portion of the chain to move freely, thereby creating a choker chain effect.

According to illustrated embodiment, the chain openings 12are located at substantially opposite ends of the body 11. In use, the chain 13 extends downwardly through one of the openings, about the load, and then extend upwardly through the other of the openings, as illustrated in Figures 1 and 2.

According to illustrated embodiment, the body includes a pair of side plate members 16 attached to another in a spaced apart configuration using bolts 17 and rigid tubular spacing members 18 through which the bolts 17 extend.

Each of the side plates are substantially T-shaped having a cross piece 19 and a substantially perpendicular downcomer portion 20. The cross pieces 19 are substantially rectangular. Each cross piece 19 has a pair of guide slots 21 to guide the slide plate 14 during movement thereof. One guide slot 21 is provided at each end of the cross piece 19 substantially in line and parallel with the upper edge of the cross piece 19. There are also two pairs of bolt openings 22 extending through each cross piece 19, each pair of openings 22 located adjacent an end of the cross piece 19. Each of these openings will receive a bolt 17 with attendant spacing member 18. The respective bolts 17 extending through each pair of bolt openings 22 define each of the chain openings 12. The terminal end of the slots 21 extend to a region which is at least partially between the bolts 17 defining the chain openings 12 in the body 11.

The cross piece 19 also includes a central pivot bolt opening 23 located adjacent the lower edge of the cross piece 19for mounting a pivot bolt.

Normally, each downcomer portion 20 is substantially rectangular and has a substantially central abutment bolt opening 25 for mounting an abutment bolt 26.

According to the illustrated embodiment, a base member 27 is provided and attached to the downcomer 20 of one of the side plates 16 and extending substantially perpendicularly from the downcomer 20. There is an opening 28 provided in the base member through which a quick release actuator 29 will extend.

The slide plate 14 has guide flanges 30 extending laterally from the plate 14 to be received in the guide openings 21 in the body 11. In use, the flanges 30 will also transfer the load exerted on the chain 13, to the body 11. Two flanges 30 are provided extending from each side each of the plate 14, one flange extending on either side, at either end of the slide plate 14.

According to the illustrated embodiment, the slide plate 14 is provided with a chain receiving slot 15 at either end. Each chain receiving slot 15 is dimensioned to correspond to the thickness of a link in the chain 13. In use, adjacent links in the chain will abut either side of the slide plate 14 when a link is located in the chain receiving slot 15. Each of the chain receiving slots 15 is substantially U- shaped with the link in the chain 11 received through the open end. The slide plate 14 also includes a central opening 32 through which an actuation lever 33 extends.

The slide plate 14 is movable such that when one portion of a chain 13 extending through one of the chain openings 12, is locked relative to the body 11, the other chain opening 12 and any chain 13 extending therethrough, is free. The slide plate 14 is movable from end to end in the body 11 in order to lock only one portion of the chain relative to the body 11 at any one time.

The chain receiving slots 15 give the ends of the slide plate 14 a pair of spaced apart tongues. The bolts 17 which define the chain openings 12 through which the chain 13 extends, provide additional support to the slide plate 14 and the ends of the tongues.

The apparatus also includes an actuation mechanism in order to move and control the movement of the slide plate 14. Normally, the actuation mechanism is sandwiched between the plate members 16 of the body 11 and in this manner is protected from accidental damage. According to the illustrated embodiment, the actuation mechanism includes an actuation lever 33, biasing springs 34 to bias the actuation lever 33 into a particular position, and a quick release mechanism.

The actuation lever 33 extends through the central opening 32 in the slide plate 14. The actuation lever 33 abuts the edges of the opening 32 such that movement of the lever 33 will move the slide plate 14. The actuation lever 33 has a pair of pin openings to receive pins or connectors, and an elongate slot 36 in order to receive a pivot bolt 24. Normally, the slot 36 extends parallel to the length of the lever 33 in a position towards the lower end of the lever 33, with an opening 35 positioned above the slot 36 and the second opening 37 positioned below the slot 36. Typically, the actuation lever 33 extends downwardly into the body 11 to a location between the downcomers 20, and there abuts the abutment bolt 26 which restricts movement of the actuation lever 33 from end to end, thereby restricting movement of the slide plate 14.

The slot opening 36 which receives the pivot bolt 24 allows the actuation lever 33 to be drawn in a direction perpendicular to the slide plate 14, to clear the abutment bolt 26, which then allows movement of the lever 33 (and the slide plate 14) from end to end in order to operate the apparatus. The actuation lever 33 is biased into the locking condition relative to one of the chain openings 12 in the body adapted to receive the chain 13.

The opening 35 above the slot opening 36 in the actuation lever 33 receives a connector used to connect the biasing springs 34. The opening 37 located below the slot opening 36 in the actuation lever 33 is used to connect the actuation lever 33 to an over centre cam 38 which is mounted for rotation about the abutment bolt 26. A quick release actuator 29 extending through the opening 28 in the base member 27, engages with the cam 38 such that upon actuation of the quick release actuator 29, the cam 38 rotates, lifting the actuation lever 33 above the abutment bolt 26 and allowing movement of the actuation lever 33 under the biasing effect.

According to the illustrated embodiment, the actuation lever 33 is biased to lock an intermediate portion of the chain 13.

When the free end of the lifting chain 13 is held captive by the slide plate 14, the rest of the chain 11 is free to move through the apparatus to create a choking effect on the load during lifting. After the load is placed and secure, the quick release actuator 29 can be pulled.

The quick release actuator 29 is attached to the cam 38 attached to the bottom of the actuation lever 33 which protrudes through the slide plate 14. As the quick release actuator 29 is pulled the cam 38 rotates using the abutment bolt 25 as a pivot, causing the actuation lever 33 to rise through the slide plate 14. This action continues until the cam 38 rotates beyond its stable position. At this point the actuation lever 33 moves laterally drawing the slide plate 14 back from its engaged state. As the slide plate 14 moves to disengage the free end of the chain 13, the other end of the slide plate 14 begins to engage the intermediate portion of the chain 11 to prevent the apparatus from falling from the chain 11.

With continued pressure on the quick release actuator 29, the cam 38 moves over centre and the springs 34 draw the actuation lever 33, and inturn the slide plate 14, into another stable position at the opposite end of the body. This new stable position ensures the intermediate portion of the chain 13 remains captive and the free end is released, thus releasing the load. The apparatus can be reset by lifting the actuation lever 33 and moving it to the opposite end to reengage the free end of the chain 13 ready to lift again.

Due to the over centre action of the cam 38, the actuation lever 33 can't move and holds the slide plate 14 in place until the quick release actuator 29 is pulled or the apparatus is reset manually. In the present specification and claims (if any), the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers.

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations. In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims

1. An attachment apparatus for a choker chain connected to a force application mechanism, the apparatus including a body having at least one chain opening therethrough adapted to receive a portion of a chain, and a slide member, slidable relative to the body between a locking condition wherein the slide member is adapted to be locked to an intermediate portion of the chain between the force application mechanism and the free end of the chain, when not in use and when in use, that is, when a load is to be lifted, the slide member is adapted to lock the free end of the chain and to allow the intermediate portion to move freely about the load, thereby creating a choker chain effect..

2. An attachment apparatus according to claim 1 wherein the slide member is in the form of a slide plate having at least one slot to engage a portion of the chain to lock the chain.

3. An attachment apparatus according to either one of the preceding claims wherein a pair of spaced apart openings are provided in the body member.

4. An attachment apparatus according to claim 3 wherein one of the openings is located at substantially opposite ends of the body and in use, the chain extends downwardly through one of the openings, about the load, and then upwardly through the other of the openings.

5. An attachment apparatus according to any one of the preceding claims wherein the body includes a pair of parallel plate members attached to another in a spaced apart configuration by fasteners and separated using spacing means mounted between the plate members.

6. An attachment apparatus according to claim 5 wherein each of the plate members is substantially T-shaped having a cross piece and a substantially perpendicular downcomer portion.

7. An attachment apparatus according to claim 6 wherein each cross piece has at least one guide opening to guide the slide member during movement thereof.

8. Aⁿ attachment apparatus according to either claim 6 or claim 7 wherein two pairs of openings extending through each cross piece, each pair located adjacent an end of the cross piece, each of the openings receiving a fastener with an attendant spacing member and the respective bolts extending through each pair of openings define each of the chain openings for the chain.

9. An attachment apparatus according to any one of claims 6 to 8 wherein the cross piece includes a central opening located adjacent a lower edge of the cross piece and adapted to mount a pivot bolt.

10. An attachment apparatus according to any one of claims 6 to 9 wherein each downcomer portion has at least one substantially central opening for mounting an abutment bolt.

11. An attachment apparatus according to any one of the preceding claims wherein the slide member is configured as an elongate slide plate, dimensioned such that when one chain opening of the body which is adapted to receive the chain, is obscured, the other of the chain openings is not obscured by the slide plate.

12. An attachment apparatus according to claim 11 wherein the plate has guide flanges extending laterally from the plate to be received in guide openings in the body.

13. An attachment apparatus according to claim 12 wherein in use, the guide flanges transfer load exerted on the chain to the body.

14. An attachment apparatus according to any one of claims 11 to 13 wherein the slide plate is provided with an opening at either end.

15. An attachment apparatus according to claim 14 wherein one of the openings in the slide plate has a divergent opening, widening as the opening extends away from the other opening.

16. An attachment apparatus according to any one of the preceding claims wherein the slide member is movable from end to end relative to the body in order to lock only one portion of the chain relative to the body at any one time.

17. An attachment apparatus according to any one of the preceding claims wherein further including an actuation mechanism in order to move and control the movement of the slide member.

18. An attachment apparatus according to claim 17 wherein the actuation mechanism includes an actuation lever, biasing means to bias the actuation lever into a particular position, and quick release means.

19. An attachment apparatus according to claim 18 wherein the actuation lever extends through a central opening in the slide plate.

20. An attachment apparatus according to claim 18 or claim 19_. wherein the actuation lever has a pair of openings to receive pins or connectors, and an elongate slot in order to receive a pivot bolt, the slot extending parallel to the length of the lever in a position towards the lower end of the lever, with a first opening positioned above the slot and the second opening positioned below the slot.

21. An attachment apparatus according to claim 20 wherein the actuation lever extends downwardly into the body to and there abuts an abutment bolt which restricts movement of the actuation lever from end to end, thereby restricting movement of the slide member.

22. An attachment apparatus according to claim 21 wherein the elongate slot which receives the pivot bolt allows the actuation lever to be drawn in a direction perpendicular to the slide member, to clear the abutment bolt, which then allows movement of the lever and the slide member from end to end in order to operate the apparatus.

23. An attachment apparatus according to any one of claims 18 to 22 wherein the actuation lever is biased into the locking condition relative to one of the chain openings in the body adapted to receive the chain.

24. An attachment apparatus according to any one of claims 18 to 23 wherein the second opening located below the slot opening in the actuation lever connects the actuation lever to an over centre cam which is mounted for rotation about the abutment bolt and a quick release actuation means engages with the cam such that upon actuation of the quick release actuation means, the cam rotates, lifting the actuation lever above the abutment bolt and allowing movement of the actuation lever, under the biasing effect.

25. An attachment apparatus according to any one of claims 18 to 22 wherein the actuation lever is biased to lock an intermediate portion of the chain.