WO2025155621A1 - Axially-mating snap-together sprocket assembly - Google Patents

Abstract

A split sprocket for conveyor belts or chains comprises a first section and a second section that mates axially and through a snap fit connection with the first section to form a sprocket with drive teeth distributed about the periphery and a central hub for retaining a shaft. At least one flexible finger engages a latching wall to latch the first and second section together. A tool can be used to unlatch the flexible finger.

Description

AXIALLY-MATING SNAP-TOGETHER SPROCKET ASSEMBLY

BACKGROUND

The invention relates generally to split sprockets that can be assembled on a drive shaft in an endless conveyor belt system.

Sprockets are used to drive endless power-transmission and conveyor belts and chains. Each sprocket is mounted on a shaft received by a bore extending axially through the sprocket. The shaft is supported at both ends by bearing blocks. A gearbox or a belt-driven pulley mounted to an end of the shaft makes the shaft a driveshaft. Installing a one-piece sprocket on a driveshaft requires that at least one bearing block be removed to slide the sprocket axially onto the shaft. Typically, the shaft also has to be lifted out of the conveyor side frame.

Split sprockets that are split along seams through their bores can be installed on shafts without removing bearing blocks. A first piece of the split sprocket is positioned on the shaft. Then, a complementary second piece is mated to the first piece. The two pieces are fastened to each other, usually by a pair of bolts or screws. One version of a split sprocket used with conveyor belts has two identical halves that fit together with mating puzzle-piece structure. Screws through the puzzle-piece structure at both seams tighten the pieces together. But the two screws do not provide much resistance to axial shifting of one sprocket half relative to the other. In addition, the need for tools to assemble the sprockets complicates assembly and disassembly.

SUMMARY

One version of a split sprocket embodying features of the invention comprises first and second sprocket sections that axially mate and snap together to form a sprocket with drive teeth distributed about the periphery thereof. A central hub in the sprocket retains a shaft. The first section includes an open peripheral portion and an open hub connected to the open peripheral portion. The second section forms a cap to close the peripheral portion and open hub. The second section in inserted along an axial direction into a space formed by the first section and snapped into place.

According to one aspect, a sprocket for a conveyor belt comprises a first sprocket section, a second sprocket section inserted in the shaped passageway to complete the peripheral portion and at least one flexible finger extending from one of the first sprocket section and the second sprocket section for engaging a first latching wall in the other sprocket section to latch the first sprocket section to the second sprocket section to form a complete sprocket. The first sprocket section has a plurality bearing surfaces defining an axially-extending opening for seating a shaft, a peripheral portion defining drive elements connected to the bearing surface and forming a space between a first end and a second end and a shaped passageway extending from the space in the curved peripheral portion to the axially-extending opening.

According to another aspect, a sprocket assembly comprising an axially-mating, snap-together sprocket comprising a first sprocket section and a second sprocket section latched to the first sprocket section with a flexible latch to form a complete periphery and a central axially-extending opening for mounting a shaft, an unlatching channel formed in the second sprocket section and an unlatching tool. The unlatching tool comprises a prong configured to pass through the unlatching channel to push the flexible latch into an unlocked position to release the second sprocket section from the first sprocket section.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric first view of an assembled split sprocket mounted on a shaft according to an embodiment of the invention;

FIG. 2 is an isometric second view of the split sprocket of FIG. 1;

FIG. 3 is an exploded view of the split sprocket of FIG. 1;

FIG. 4 is an isometric view of a first section of the split sprocket of FIG. 1;

FIG. 5 is a detailed view of the latching passageway in the first section of FIG. 4;

FIG. 6A is top detailed view of a flexible latching finger of the first section of FIG. 4;

FIG. 6B is an isometric detailed view of the flexible latching finger of FIG. 6 A;

FIG. 7A is a front view of the second section of the split sprocket of FIG. 1;

FIG. 7B is a rear view of the second section of FIG. 7A;

FIG. 8 is a top detailed view of a latching protrusion of the second section of FIG. 7;

FIG. 9 A is a sectional top view of the split sprocket of FIG. 1 at the start of assembly; FIG. 9B is a detailed view of the split sprocket section of FIG. 9 A;

FIG. 10A is a sectional top view of the split sprocket of FIG. 1 during assembly; FIG. 1 OB is a detailed view of the split sprocket section of FIG. 10 A;

FIG. 11 A is a sectional top view of the assembled split sprocket of FIG. 1;

FIG. 1 IB is a detailed view of the split sprocket section of FIG. 11 A;

FIG. 12 shows the split sprocket of FIG. 1 and a tool for separating the split sprocket according to an embodiment;

FIG. 13A shows the split sprocket and tool of FIG. 12 during insertion of the tool into the split sprocket to initiate disassembly;

FIG. 13B is a detailed view of a portion of the split sprocket and tool in FIG. 13A

FIG. 14A shows the split sprocket and tool of FIG. 12 during unlatching of the sprocket sections using the tool;

FIG. 14B is a detailed view of the latching region in FIG. 14A during unlatching using the tool;

FIG. 15 is a cross-sectional view of a sprocket assembly comprising a plurality of split sprockets arranged on a shaft according to an embodiment;

FIG. 16 is an isometric view of the shaft of FIG. 15;

FIG. 17 is an isometric view of a shaft for a sprocket assembly according to another embodiment;

FIG. 18 is an isometric view of a shaft for a sprocket assembly according to another embodiment;

FIG. 19 is an isometric view of a stacked sprocket assembly comprising split sprockets arranged on a shaft according to another embodiment;

FIGS. 20A and 20B show a split sprocket and shaft according to another embodiment;

FIG. 21 is an isometric view of a split sprocket and tool for opening the split sprocket according to another embodiment;

FIG. 22 is a detailed vied of the latching passageway of the split sprocket of FIG. 21;

FIG. 23 is a detailed view of a portion of a split sprocket according to another embodiment;

FIG. 24 is a detailed view of the latching passageway of FIG. 23;

FIG. 25 is a detailed view of a portion of a split sprocket according to another embodiment; FIG. 26 is a detailed view of a portion of a split sprocket according to another embodiment;

FIG. 27 is a detailed view of a portion of a split sprocket according to another embodiment;

FIG. 28 is a detailed view of a latching portion of a split sprocket according to another embodiment;

FIG. 29 is a detailed view of a portion of a split sprocket according to another embodiment;

FIG. 30 is a detailed view of a portion of a split sprocket according to another embodiment.

DETAILED DESCRIPTION

A split sprocket for driving or otherwise engaging a conveyor belt comprises multiple portions that slide axially relative to each other and snap into engagement about a rotatable shaft using flexible fingers. The invention will be described below relative to certain illustrative embodiments, though the invention is not limited to the illustrative embodiments.

One version of a split sprocket embodying features of the invention is shown in FIGS. 1-3. The illustrative split sprocket 10 comprises two sections: a first section, shown as a base portion 60, and a second section, shown as a cap portion 20. The base portion 60 and cap portion 20 include mating features that interlock the two portions radially and circumferentially. The cap portion 20 slides axially relative to the base portion 60 and snaps into engagement with the base portion 60 to form a complete sprocket having peripheral drive elements, shown as teeth 25, for engaging drive structure on a conveyor chain or belt. The illustrative teeth are spaced equally around the circumference of the periphery at a constant pitch. However, the invention is not limited to the illustrative drive element configuration, and the drive structure may have any suitable size, shape, pitch, and configuration suitable for engaging a conveyor belt or chain. In the illustrative embodiment, the base portion and the cap portion are joined together in a puzzle pattern to form the complete sprocket, though any suitable connection means may be used to join together the two sections. Each section 20, 60 may comprise a single unitary piece or multiple subpieces coupled together. In this example, the two sections are shaped differently, with the first section 60 being the larger section. The illustrative base portion 60 is curved and spans the majority of the circumference of the sprocket except for a space in the periphery between two ends, with the cap portion 20 inserted in the space and completing the circumference when mated to the base portion 60.

The sprocket 10 forms a central opening for receiving a shaft 12 extending in an axial direction.

Referring to FIGS. 4 and 5, which show the base portion 60 alone, the illustrative base portion includes a hub comprising three bearing walls 64, 65, 66 defining a portion of the central axially-extending opening 29 for receiving the shaft 12. The bearing walls may be shaped and— or include cleaning recesses. A fourth end of the central opening 29 is open and is closed by the cap portion 20 when inserted. Bearing surface 66 includes a positioning tab 67, as described below.

The illustrative base portion 60 includes spokes radiating from the hub and extending to the periphery, but any suitable means for connecting the central opening 29 to the periphery may be used. For example, the base portion 60 may be solid from the central opening 29 to the periphery. The base portion 60 extends from a first face 61 to a second face 62 (shown in FIGS. 3 and 5), which in the illustrative embodiment are flat, but the invention is not so limited.

A latching passageway 40 extends from the open end of the central opening 29 to the periphery and receives and locks the cap portion 20. The cap portion 20 is configured to be inserted into the latching passageway 40 along an axial direction parallel to the axis of the drive shaft and snapped into engagement. The shaft 12 is inserted into the central opening 29 via the latching passageway 40 prior to inserting the cap portion 20. The latching passageway 40 is configured and sized to allow the shaft 12 to pass therethrough.

The latching passageway 40 includes axially-extending central recesses 42 on each side thereof for receiving complementary protrusions on the cap portion 20. The axially- extending recesses 42 are open to the second face 62 and closed to the first face 61 by stopping walls 43. Top axially-extending recesses 46 extend from the periphery through the thickness of the base portion 60 and include stopping walls 47 in the first face 61. The top recesses 46 are open to the second face 62. Rounded protrusions 48 adjacent the lower axially-extending recesses 42 are configured to engage corresponding recesses in the cap portion 20, while upper rounded protrusions 49 adjacent the upper recesses 46 engage corresponding recesses in the cap portion. The illustrative recesses 46 are slightly hooked at the tip towards the latching passageway 40.

The radially outer portion of the latching passageway 40 includes flexible latching fingers 72, 74 extending axially from the first end face 61 to the second end face 62. Each latching finger is spaced inwards from the upper rounded protrusions 49 and connected at the first face 61 by a flexible connecting piece 75, forming a living hinge.

As shown in detail in FIGS. 6A and 6B, a flexible latching finger 72 includes an elongated body extending from the flexible connecting piece and terminating in a barbed tip 81. The barbed tip 81 comprises a laterally-extending flat end wall 84 slightly inset from and parallel to the end face 62. An angled wall 82 extends away from the end wall 84 and angles inwards towards the center of the latching passageway. The angled wall 82 intersects a flat, laterally-extending latching wall 83 at an acute angle. The latching wall 83 is preferably perpendicular to the axial direction, but can alternatively be skewed. An axially-extending flat wall 86 extends from the latching wall 83 and transitions to outwardly-angled wall 85, which reduces the thickness of the finger 72. The outwardly-angled wall 85 transitions to another axially extending wall 87 extending to the base of the finger 72. An axially- extending wall 88 defines a side of the finger 72 opposite the barbed tip 81 and may flare slightly outwards towards the tip end with angled wall 89. Angled wall 89 transitions to axially-extending wall 90, which intersects the flat end wall 84 at a right angle, but the invention is not so limited.

As shown in FIG. 6B, the body of the flexible finger 72 is offset from the upper rounded protrusions 49, so that the connecting piece 75 swoops to connect them.

In addition, each barbed tips 72, 74 includes a ramped surface 91. The ramped surface 91 reduces the thickness of the tip 81 in the radial direction.

FIGS. 7A and 7B show the cap portion 20 in detail. The illustrative cap portion 20 comprises a shaped body extending from a peripheral end 24 configured to complete the periphery of the sprocket 10 to an inner end 23 configured to complete the central opening 29. The inner end 23 can include a bearing surface for the shaft 12. The peripheral end 24 includes teeth 25. The cap portion extends axially from a first face 21 (see FIG. 8) to a second face 22. The first face 21 aligns with the first face 61 of the base portion 60 and the second face 22 aligns with the second face 62 of the base portion 60 when the sprocket is assembled.

The shaped body includes outer shaped wings 34 extending from each side and configured to mate with outer recesses 46 and rounded protrusions 49. Inner shaped wings 36 extend from each side of the shaped body at the inner end. The inner shaped wings are configured to mate with recesses 42 and rounded protrusions 48.

The cap portion 20 further includes latching projections 52, 54 on each side of the shaped body for engaging the flexible latching fingers 72, 74. As shown in FIG. 8, an illustrative latching protrusion 54 comprises a laterally-extending flat latching wall 57 extending perpendicular to the body of the cap portion 20. The latching wall 57 intersects an axially-extending wall 58 at a right angle. The axially-extending wall 58 transitions to an angled wall 56 extends inwards to intersect another axially extending wall 55 defining a side wall of the cap portion 20. Between the latching wall 57 and the end face 22, the cap portion further includes a shallow nook 59 to facilitate unlatching of the cap portion 20, as described below.

Each shallow nook 59 aligns with a tunnel 28 extending to the periphery of the cap portion 20. Each tunnel 28 passes behind a latching projection 52, 54 and is configured to receive a prong of an unlatching tool to unlatch the flexible latching fingers, as described below.

The illustrative cap portion 20 further includes a radial channel 26 in the first end face 21 of the shaped body. The radial channel 26 can be used to guide a stabilizing prong on the unlatching tool, but the invention is not limited to the illustrative channel 26.

FIGS. 9A— 11B illustrate the process of inserting and latching the cap portion 20 to the body portion 60 to form a complete sprocket. As shown in FIGS. 9A and 9B, first, the cap portion 20 is aligned with the latching opening 40 in the base portion 60 and moved in an axial direction 12 into the latching opening 40. As the cap portion 20 moves into engagement, the inner shaped wings 36 enter the axially-extending recesses 42 and the outer shaped wings 34 enter the upper axially-extending recesses 46. The latching protrusions 52, 54 approach the latching fingers 72, 74. As the cap portion 20 is inserted, the angled surfaces 56 and 82 confront each other and slide over each other to compress the fingers 72, 74, as shown in FIGS. 10A and 10B, allowing the cap portion 20 to slide through the opening 40 until bottomed out by walls 43 and 47. When walls 83 in the flexible fingers clear latching walls 57, the flexible fingers spring back to the relaxed position, with the walls 83 latched axially behind the walls 57, latching the cap portion 20 to the base portion 60, as shown in FIGS. 11 A and 11B.

To disassemble and— or remove the sprocket 10, a tool may be used to unlatch the cap portion 20 from the base portion, as shown in FIGS. 12— 14B. An illustrative unlocking tool 110 comprises a base 111 and a plurality of unlatching prongs 112, 113, 114. The illustrative tool includes two prongs 112, 113 spaced apart at a first end and a third prong 114 extending from a central region on the second end of the base. The illustrative prongs 112, 113, 114 have circular cross-sections with rounded, tapering tips forming domes.

To unlatch the cap portion 20 from the base portion 60, the prongs 112, 113 are aligned with the tunnels 28 in the cap portion 20 and the prong 114 is aligned with the channel 26 on the end face 21 of the cap portion, as shown in FIG. 12. The tunnels 28 and channel 26 extend perpendicular to the axis of the shaft 12.

Then, as shown in FIGS. 13A and 13B, the prongs 112, 113 are inserted into the tunnels 28 and prong 114 is inserted through the channel 26 until the prongs 112, 113 reach the ramped surfaces 91 of the flexible finger tips. As the tool 110 pushes the prongs 112, 113, 114 further against the ramped surfaces 91, the flexible fingers 72, 74 retract from the latched position, as shown in FIGS. 14A and 14B. With the latching walls 83, 57 clear of each other, the cap portion 20 can be slid axially out of the opening 40 to open the sprocket 10. The generally perpendicular-to-the-shaft-axis motion of the tool 110 is the primary motion that unlocks the flexible fingers 72, 74. The geometry of the tunnels 27 and channel 26 in the sprocket guide the tool 110 in the generally perpendicular direction and support the tool 110 against forces generated by the sprocket that are not in the direction of the tool insertion motion.

Referring to FIGS. 15 and 16, a sprocket assembly 210 can comprise a plurality of axially-mating, snap-together sprockets 10 mounted on a shaft 12. As described above, a base portion can include a positioning tab 67 on a bearing surface 66. The positioning tab 67 is received in a groove or recess on the shaft to control the axial position of the sprocket 10 on the shaft.

In one embodiment, a sprocket assembly shaft 12 includes different sized recesses for each sprocket for receiving a positioning tab 67. For example, the shaft 12 of FIGS. 15 and 16 includes a smaller central recess 14 for locking a central sprocket 10a. The shaft 12 includes elongated grooves 16 in mounting regions on each side of the central recess 14 to allow the associated sprockets 10b, 10c to float axially along the shaft.

As shown in FIG. 17, a sprocket mounting shaft 121 can include equally-sized recesses 17 spaced apart along the shaft for mounting a series of spaced-apart sprockets with minimal float.

FIG. 18 shows another embodiment of a shaft 122 for a sprocket assembly including a single axially-extending groove 18 for receiving positioning tabs on associated sprockets.

As shown in FIG. 19, a shaft 122 with an elongated groove 18 can be used to mount a series of stacked two-piece, snap-together sprockets 10'.

FIGS. 20A and 20B show another embodiment of a two-piece, snap-together sprocket 210 on a shaft 12. The illustrative sprocket 210 comprises a base portion 260 that seats the shaft 12 and a cap portion 220 that slides axially into a space formed by the base portion 260 and snaps into engagement with the base portion 260 to form a complete sprocket 210. In the embodiment of FIGS. 20A and 20B, the cap portion 220 is larger than the cap portion 20 wraps around the shaft 12. The illustrative design is suitable for larger shaft sizes to include more shaft bearing surfaces on the cap portion 220.

In another embodiment, shown in FIGS. 21 and 22, a two-piece, snap-together sprocket 310 includes a base portion 360 with flexible latching fingers 372, 374 extending in opposite directions. An associated tool 311 for unlocking a cap portion 320 from the base portion 360 includes central prongs 314, 315 for straddling the cap portion 320 and an unlocking prong 312 for unlatching a finger 374 and allowing the cap 320 to slide axially out of engagement with the base portion.

Referring to FIGS. 23 and 24, another embodiment of a two-piece, snap-together sprocket 410 includes a base portion 460 and an axially-mating cap portion 420. The base portion includes a central opening 29 for receiving a shaft and a latching passageway 440 for receiving the cap portion 420. The base portion and axially-mating cap portion are configured to fit in a puzzle-like configuration. The cap portion 420 further includes retractable latching fingers 472, 474 that engage notches 452, 454 in the base portion. The retractable latching fingers 472, 474 include openings 476, 477 for receiving prongs 413, 414 of an unlatching tool. To unlatch the cap portion 420, a user squeezes the tool to compress the prongs 413, 414, lifting the fingers out of engagement with the notches 452, 454. Then, the cap portion 420 can slide axially out of engagement with the base portion 460.

FIG. 25 shows another embodiment of a of a two-piece, snap-together sprocket 510 includes a base portion 560 and an axially-mating cap portion 520. The cap portion 520 includes retractable latching fingers 574, 572 that can be retracted using a tool 515. The illustrative latching finger 572, 574 have latching tips at a peripheral end, but the invention is not so limited.

FIG. 26 shows another embodiment of a of a two-piece, snap-together sprocket 610 includes a base portion 660 and an axially-mating cap portion 620. The cap portion 620 includes retractable latching fingers 672, 674 that can be retracted using a tool. The illustrative latching finger 672, 674 retract in a middle portion by inserting prongs in central openings formed in the fingers.

FIG. 27 shows another embodiment of a of a two-piece, snap-together sprocket 710 includes a base portion 760 and an axially-mating cap portion 720. The cap portion 720 includes retractable latching fingers 774, 772 that can be retracted using a tool 715. The illustrative latching finger 772, 774 have latching tips at a radially inner end, but the invention is not so limited.

In another embodiment, shown in FIG. 28, a two-piece, snap-together sprocket 810 includes a base portion 860 and an axially-mating cap portion 820 with latchable levers 872, 874 extending from each side for latching the cap portion 820 to the base portion 860. Each lever 872, 874 includes an edge recess for receiving a corresponding latching protrusion in a latching passageway of the base portion. A tool 815 can selectively lift each lever out of the latching position to release the cap portion 820 and allow it to slide axially out of engagement with the base portion. In another embodiment, shown in FIGS. 29, a two-piece, snap-together sprocket 910 includes a base portion 960 and an axially-mating cap portion 920 with a single latchable lever 972 that can be unlatched using a tool 915.

As shown in FIG. 30, in another embodiment, a two-piece, snap-together sprocket 1010 includes a base portion 1060 and an axially-mating cap portion 1020 including an unlatching tunnel extending through a peripheral portion for receiving a tool 1015 to selectively depress a latchable lever 1072.

Although the invention has been described in reference to a version of a split sprocket, other versions are possible. For example, the periphery does not have to be toothed; it could be smooth like a roller, or grooved like a pulley. So, the term sprocket as used in the claims is meant to encompass split wheels with or without teeth on their peripheries.

Claims

What is claimed is:

1. A sprocket for a conveyor belt comprising: a first sprocket section having a plurality bearing surfaces defining an axially-extending opening for seating a shaft; a peripheral portion defining drive elements connected to the bearing surface and forming a space between a first end and a second end; and a shaped passageway extending from the space in the curved peripheral portion to the axially-extending opening; a second sprocket section inserted in the shaped passageway to complete the peripheral portion; and at least one flexible finger extending from one of the first sprocket section and the second sprocket section for engaging a first latching wall in the other sprocket section to latch the first sprocket section to the second sprocket section to form a complete sprocket.

2. The sprocket of claim 1, wherein the at least one finger comprises a first axially- extending finger within the shaped passageway and the latching wall is formed on a latching projection on the second sprocket section.

3. The sprocket of claim 2, wherein the finger comprises an elongated body extending from a flexible connecting piece connected to a first face of the first sprocket section.

4. The sprocket of claim 1, wherein the flexible finger includes an elongated body that terminates in a barbed tip.

5. The sprocket of claim 4, wherein the barbed tip comprises a laterally-extending flat end wall; an angled wall extending away from the end wall and angled inwards towards the center of the latching passageway; and a finger latching wall intersecting the angled wall at an acute angle for engaging the first latching wall.

6. The sprocket of claim 5, wherein the barbed tip further comprises a ramped surface that reduces a thickness of the barbed tip in a radial direction.

7. The sprocket of claim 5, wherein the second sprocket section includes a body extending from an inner end configured to complete the axially- extending opening to a peripheral end configured to complete the periphery of the sprocket; and a latching projection including the first latching wall extending from a side wall of the body.

8. The sprocket of claim 7, wherein the latching projecting comprises: the first latching wall extending perpendicular to the body; an axially-extending wall intersecting the latching wall at a right angle; and an angled wall extends inwards from the axially-extending wall to intersect the side wall.

9. The sprocket of claim 8, further comprising a shallow nook between the first latching wall and an end face of the cap portion to facilitate unlatching of the cap portion.

10. The sprocket of claim 9, further comprising an unlatching tunnel extending from the peripheral end of the cap portion to the shallow nook for receiving an unlocking tool.

11. The sprocket of claim 1, wherein the second sprocket section further includes a first set of shaped wings extending from each side of a shaped body and configured to mate with a first set of axially-extending recesses in the first sprocket section.

12. The sprocket of claim 11, wherein the second sprocket section further includes a second set of shaped wings extending from each side of the shaped body at the inner end, the second set of shaped wings configured to mate with a second set of axially-extending recesses in the second sprocket section.

13. The sprocket of claim 12, wherein the first and second set of axially-extending recesses are closed to a first face of the second sprocket section and open to a second face of the second sprocket section.

14. The sprocket of claim 1, further comprising a positioning tab extending from a bearing surface for engaging a recess in the shaft.

15. The sprocket of claim 1, wherein the at least one flexible finger comprises: a first flexible finger connected to a first face of the first sprocket section by a flexible connecting piece and extending axially along a first side of the shaped passageway; and a second flexible finger connected to the first face of the first sprocket section by a flexible connecting piece and extending axially along a second side of the shaped passageway.

16. The sprocket of claim 1, wherein the at least one flexible finger extends from the second sprocket section and engages a notch in the first sprocket section forming the latching wall.

17. The sprocket of claim 1, wherein the at least one finger comprises a radially extending finger extending from the second sprocket section.

18. A sprocket assembly, comprising: an axially-mating, snap-together sprocket comprising a first sprocket section and a second sprocket section latched to the first sprocket section with a flexible latch to form a complete periphery and a central axially-extending opening for mounting a shaft; an unlatching channel formed in the second sprocket section; and an unlatching tool comprising a prong configured to pass through the unlatching channel to push the flexible latch into an unlocked position to release the second sprocket section from the first sprocket section.

19. The sprocket assembly of claim 18, wherein the unlatching channel extends from the periphery to the flexible latch.

20. The sprocket assembly of claim 18, wherein the unlatching channel extends perpendicular to the axis of the shaft.