WO2017075427A1

WO2017075427A1 - Shackle assembly

Info

Publication number: WO2017075427A1
Application number: PCT/US2016/059432
Authority: WO
Inventors: Damon Elwood Dilworth; Michael Paul BLOINK; Matthew DICIANNI
Original assignee: Hendrickson Usa, L.L.C.
Priority date: 2015-10-29
Filing date: 2016-10-28
Publication date: 2017-05-04

Abstract

A shackle for mounting a suspension spring to a vehicle frame includes a pair of flanges joined by a bridge portion. Each flange includes an outer plate portion joined to a wear plate portion with a fastener channel formed therebetween. Each flange includes a pair of pin recesses that are configured to receive the ends of upper and lower bar pin bushings that are pivotally received within a bracket attached to the vehicle frame and an eye of the spring, respectively. The bridge portion that joins the flanges includes stop surface configured to engage the bracket to limit pivoting of the shackle about an axis defined by the upper bar pin bushing.

Description

SHACKLE ASSEMBLY

CLAIM OF PRIORITY

[0001] This application claims the benefit of U.S. Provisional Application No. 62,248,052, filed October 29, 2015, the contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present disclosure relates generally to vehicle suspension systems and, in particular, to shackle assemblies used to connect vehicle suspension components to a vehicle frame.

BACKGROUND

[0003] Shackle assemblies are typically used to in a variety of vehicle suspensions to connect suspension components to a vehicle frame.

[0004] An example of a typical use of a shackle assembly is attaching an end of a leaf spring of a vehicle suspension to a vehicle frame. In a trailing-arm suspension, on each side of the vehicle, the vehicle axle is attached to a leaf spring, typically around the middle of the leaf spring, and the ends of the leaf spring are typically attached to a vehicle frame rail using a frame hanger at a leading end and a shackle assembly at the trailing end. The trailing end of the spring typically is formed into an eye. A shackle bracket is attached to the vehicle frame and features a lower portion with a cylindrical opening positioned below the vehicle frame rail. A pair of wear plates are positioned so that the lower portion of the shackle bracket and the eye of the trailing end of the leaf spring are sandwiched therebetween. Furthermore, a pair of shackle plates are positioned so that the wear plates (with the shackle bracket and leaf spring) are sandwiched therebetween. This assembly is secured together by an upper fastener (such as a nut and bolt) and can-style bushing passing through the cylindrical bore of the shackle bracket and a lower fastener and can-style bushing passing through the eye of the leaf spring trailing end, with the upper and lower fasteners passing through corresponding openings formed in the pair of wear plates and the pair of shackle plates.

[0005] A disadvantage of the above shackle assembly is that the multiple pieces (separate wear and shackle plates) increase the difficultly of installation. Furthermore, both shackle plates and wear plates must be inventoried, increasing the chances that parts may run out of stock or be misplaced.

[0006] A further consideration is that some vehicle and suspension manufacturers prefer to use bar pin bushings in place of traditional cylindrical bushings and fasteners in shackle assemblies. Bar pin bushings typically include an enlarged central portion, that serves as the bushing, and end portions, where the end portions are adapted to be secured within a bracket or fixture. The central bushing portion of the bar pin bushing may include a rubber layer or may be capable of being greased (i.e. greasable), the latter typically avoiding the need for replacement of the bushing. Greasable bar pin bushings typically feature an elongated trough, that is parallel to the longitudinal axis of the bar pin, and a grease passage that runs internally from an end of the bar pin to the trough. A multi-piece shackle assembly of the type described above typically cannot accommodate a bar pin bushing.

[0007] Another consideration when the shackle assembly is used to secure the end of a leaf spring to the frame is the desirability of providing redundancy in the event of leaf spring breakage so that vehicle control may be retained. More specifically, without some form of redundancy, an axle attached to a leaf spring that is broken on one side of the axle may undergo extensive longitudinal movement relative to the vehicle chassis if the vehicle is moving and the brakes are suddenly applied. Such a redundancy may be provided via an additional leaf spring with a "military wrap." Alternatively, shackle assemblies with built-in redundancy features have been developed, and example of which is illustrated in commonly-owned U.S. Patent No. 7,229,088 to Dudding et al. While the redundancy features of the Dudding et al. '088 patent perform well, the axle assembly disclosed therein is a multi-piece design (i.e. separate wear plates and shackle plates) and thus suffers from the disadvantages described above. Furthermore, the redundancy features are incorporated into the shackle plates and thus may be inadvertently omitted or installed incorrectly so as not to function properly. [0008] A shackle assembly that addresses at least some of the above issues is desirable.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Fig. 1 is a perspective view of a portion of a vehicle frame and a suspension system including an embodiment of the shackle assembly of the present disclosure;

[0010] Fig. 2 is an enlarged exploded left side plan view of one of the shackle assemblies and a portion of one of the leaf springs of the suspension of Fig. 1;

[0011] Fig. 3 is an exploded rear right side perspective view of the shackle assembly of Fig. 2;

[0012] Fig. 4 is an enlarged front left side perspective view of the shackle assembly and a portion of one of the frame rails and a portion of one of the leaf springs of Fig. 1;

[0013] Fig. 5 is a bottom plan view of the shackle assembly and frame rail and leaf spring portions of Fig. 4;

[0014] Fig. 6 is a top plan view of the shackle of Figures 1-5 with a bar pin bushing installed;

[0015] Fig. 7 is a rear left side perspective view of the configuration of the shackle assembly of Figs. 1-5 when the leaf spring on the opposite side of the axle has broken and a braking force is being applied.

SUMMARY

[0016] There are several aspects of the present subject matter which may be embodied separately or together in the devices and systems described and claimed below. These aspects may be employed alone or in combination with other aspects of the subject matter described herein, and the description of these aspects together is not intended to preclude the use of these aspects separately or the claiming of such aspects separately or in different combinations as set forth in the claims appended hereto.

[0017] In one aspect, a shackle for mounting a suspension spring to a bracket secured to a frame of a vehicle includes first and second wear plate portions and first and second outer plate portions. A first connector portion connects the first wear plate portion to the first outer plate portion so that a first flange having a first fastener channel between the first wear plate portion and first outer plate portion is defined. A second connector portion connects the second wear plate portion to the second outer plate portion so that a second flange having a second fastener channel between the second wear plate portion and second outer plate portion is defined. The first flange includes a first pair of spaced apart pin recesses. The second flange includes a second pair of spaced apart pin recesses that are aligned with the first pair of spaced apart pin recesses. The first and second pair of pin recesses are configured to receive an upper bar pin bushing attached to the bracket secured to the vehicle frame and a lower bar pin bushing attached to the suspension spring. The first and second fastener channels are configured to receive fasteners for securing the upper and lower bar pin bushings within the first and second pair of bar pin recesses. A bridge portion connects the first flange to the second flange. The bridge portion includes a first stop surface configured to engage the bracket attached to the vehicle frame to limit pivoting of the shackle about an axis defined by the upper bar pin bushing.

[0018] In another aspect, a shackle assembly for mounting a suspension leaf spring having an eye portion to a frame of a vehicle includes a shackle having a first flange having a first fastener channel and a first upper pin recess and a spaced apart first lower pin recess. A second flange has a second fastener channel and a second upper pin recess and a spaced apart second lower pin recess. A bridge portion connects the first flange to the second flange and includes a first shackle stop surface. A shackle bracket is configured to be attached to the vehicle frame. The shackle bracket includes a bore and a first side including a first bracket stop surface. An upper bar pin bushing has a central portion positioned within the bore of the shackle bracket and first and second end portions positioned within the first and second upper pin recesses, respectively. A lower bar pin bushing has a central portion positioned within the eye portion of the leaf spring and first and second end portions positioned within the first and second lower pin recesses, respectively. A first fastener is positioned within the first fastener channel and secures the first ends of the upper and lower bar pin bushings within the first upper and lower pin recesses of the first flange. A second fastener is positioned within the second fastener channel and secures the second ends of the upper and lower bar pin bushings within the second upper and lower pin recesses of the second flange. The first shackle stop surface opposes the first bracket stop surface and is configured to engage the first bracket stop surface to limit pivoting of the shackle about an axis defined by the upper bar pin bushing.

[0019] In yet another aspect, a suspension for supporting a vehicle frame on an axle includes a leaf spring having a proximal end with a proximal eye portion, a distal end with a distal eye portion and a middle portion positioned between the proximal and distal ends configured to attach to the axle. A frame hanger is pivotally attached to the proximal eye portion of the leaf spring and is configured to be attached to the vehicle frame. A shackle includes a first flange having a first fastener channel and a first upper pin recess and a spaced apart first lower pin recess. A second flange has a second fastener channel and a second upper pin recess and a spaced apart second lower pin recess. A bridge portion connects the first flange to the second flange and includes a first shackle stop surface. A shackle bracket is configured to be attached to the vehicle frame and includes a bore and a first side having a first bracket stop surface. An upper bar pin bushing has a central portion positioned within the bore of the shackle bracket and first and second end portions positioned within the first and second upper pin recesses, respectively. A lower bar pin bushing has a central portion positioned within the distal eye portion of the leaf spring and first and second end portions positioned within the first and second lower pin recesses, respectively. A first fastener is positioned within the first fastener channel and secures the first ends of the upper and lower bar pin bushings within the first upper and lower pin recesses of the first flange. A second fastener is positioned within the second fastener channel and secures the second ends of the upper and lower bar pin bushings within the second upper and lower pin recesses of the second flange. The first shackle stop surface opposes the first bracket stop surface and is configured to engage the first bracket stop surface to limit pivoting of the shackle about an axis defined by the upper bar pin bushing.

DETAILED DESCRIPTION OF EMBODIMENTS

[0020] A steering axle/front suspension system incorporating an embodiment of the shackle assembly of the present disclosure is indicated in general at 10 in Fig. 1. It is to be understood that although the shackle assembly is illustrated as being positioned at the rear end a leaf spring of the suspension system, the shackle assembly of the present dislcosure could alternatively be used at the opposite end of the leaf spring. [0021] Furthermore, while a single-leaf leaf spring suspension is illustrated, it is to be understood that the shackle assembly of the present disclosure is not limited to use in single-leaf leaf spring suspensions and is not limited to front suspensions. Still further, the shackle assembly of the present disclosure may be used with suspensions other than purely mechanical suspensions, such as combination air-mechanical suspensions.

[0022] As illustrated in Fig. 1, the suspension system 10 includes two single-leaf leaf springs 12a and 12b. Each single-leaf leaf spring 12a and 12b is provided with a cylindrical eye portion 14a and 14b, respectively, integrally formed at the proximal end thereof. Each eye portion 14a and 14b is pivotally connected to a standard or existing frame hanger 16a and 16b, respectively. As shown, the frame hangers 16a and 16b are mounted on fore-and-aft extending chassis frame rails 18a and 18b. Each frame rail 18a and 18b is constructed as a conventional C-shaped rail.

[0023] A vehicle axle beam 22 extends from one side of front suspension system 10 to the other side and is attached to the central portion of each leaf spring 12a and 12b by a clamping arrangement of the type known in the art. While an axle clamping arrangement featuring U-bolts 24a and 24b is shown, any alternative prior art axle clamping arrangement may be used.

[0024] Shock absorbers 26a and 26b are also included on each side of suspension system 10. Each shock absorber 26a and 26b is pivotally connected at its upper end to a bracket 28a and 28b (not shown), respectively, mounted on a corresponding frame rail and is attached at its bottom end to axle beam 22 by a fitting 32a and 32b, respectively.

[0025] The distal end portion of each single-leaf leaf spring 12a and 12b has a cylindrical eye portion 34a and 34b, respectively. Each eye portion is connected to a corresponding frame rail by a shackle assembly indicated in general at 36a and 36b. While shackle assembly 36a will be described below, it is to be understood that shackle 36b features the same construction and functionality.

[0026] With reference to Figs. 2-5, the shackle assembly 36a includes a shackle, indicated in general at 40. The shackle includes a pair of wear plate portions 42a and 42b and a pair of outer plate portions 44a and 44b. The wear plate portions and outer plate portions are joined by arcuate connector portions 46a and 46b (best shown in Fig. 4) so that shackle flanges, indicated in general at 48a and 48b, are formed. Of course connector portions 46a and 46b may feature an alternative shape. A bridge portion 52 connects the flanges 48a and 48b of the shackle.

[0027] Shackle 40 is preferably formed from a single piece of sheet metal, but may alternatively be molded or formed from multiple pieces that are joined together using any fastening means known in the art (including, but not limited to, welding) and of alternative materials.

[0028] Each shackle flange 48a and 48b includes a generally U-shaped fastener channel 54a and 54b (Figs. 3 and 5). In addition, upper and lower notches formed in wear plate 42a and outer plate 44a and connector portion 46a form upper and lower pin recesses 56a and 58a within flange 48a (Figs. 2 and 3). Flange 48b similarly features upper and lower pin recesses 56b and 58b.

[0029] A shackle bracket, indicated in general at 62 (Figs. 2 and 4), features opening 64 for receiving fasteners to fixedly attaching the bracket to a frame rail, as illustrated for frame rail 18a in Fig. 4. In addition, the shackle bracket includes a cylindrical bore 66 for receiving a bar pin bushing, as described in greater detail below. The shackle bracket also includes a pair of stop surfaces 68 and 72, the functionality of which will also be explained below.

[0030] A bar pin bushing, indicated in general at 74, is shown in Fig. 6 installed in the shackle 40 for illustrative purposes only. In the actual installation, the bar pin bushing passes through either the eye portion of the leaf spring or the cylindrical bore of the shackle bracket. As illustrated in Fig. 6, the bar pin bushing features a central bushing portion 76 and a pair of end portions, indicated in general at 78a and 78b. As is clear from Fig. 6, the central bushing portion 76 has a larger diameter than end portions 78a and 78b. The diameters of bar pin bushing end portions are sized so that they may be received within the upper and lower pin recesses of the shackle flanges 48a and 48b. The central bushing portion of the bar pin bushing may include a elastomeric or rubber surface, such as provided by an elastomeric or rubber sleeve, or may include a grease trough with an opening in fluid communication with a passage having an exposed opening in one of the bar pin end portions so as to provide a greasable bushing.

[0031] As illustrated in Fig. 6, the end portions 78a and 78b of the bar pin bushing are provided with circumferential grooves 82a and 82b. During installation, the end portions 78a and 78b of the bar pin are inserted into either the upper or lower pin recesses of the flanges 48a and 48b with the circumferential grooves positioned within the channels. The central bushing portion of the bar pin is positioned within either the cylindrical bore of the shackle bracket or the eye portion of the leaf spring, as will be explained in greater detail below. A pair of fasteners, such as through bolts 84a and 84b, are inserted through the fastener channels 54a and 54b so as to engage the circumferential grooves 82a and 82b on the end portions of the bar pin bushing. As a result, the bar pin bushing 74 is secured within the shackle 40. It should be noted that the circumferential grooves 82a and 82b of the bar pins may be replaced with indentations, such as those illustrated at 88 in Fig. 3 for bar pin bushing 94.

[0032] Returning to Figs. 2-5, use of the shackle 40 to attach the leaf spring 12a to the frame rail 18a will now be explained. An upper bar pin bushing 92 is inserted through the bore 66 of the shackle bracket 62, with the central bushing portion of the bar pin bushing positioned within the bore and the end portions extending horizontally from each side of the shackle bracket. A lower bar pin bushing 94 is similarly inserted through the eye portion 34a of leaf spring 12a. Of course the order for inserting the bar pin bushings through the shackle bracket bore and the leaf spring eye may be reversed.

[0033] The ends of the upper and lower bar pins next are positioned within the upper and lower pin recesses of the shackle flanges 48a and 48b, as illustrated in Figs. 4 and 5. A pair of fasteners, such as through bolts 96a and 96b, are next inserted through the fastener channels 54a and 54b of the shackle flanges 48a and 48b so as to engage the grooves formed in the end portions of the bar pin bushings, as illustrated at 98a and 98b in Fig. 5 for lower bar pin bushing 94. The through bolts are then secured in place with nuts 102a and 102b.

[0034] As illustrated Fig. 3, the bridge portion 52 of the shackle 40 is provided with a tab 104 featuring a stop surface 106. As illustrated in Fig. 1, during normal operation of the vehicle, the stop surface 106 will oppose and be spaced apart from the corresponding stop surface 72 formed on shackle bracket 62.

[0035] With reference to Fig. 1, in situations where the leaf spring 12a breaks, it is desirable to limit resulting longitudinal movement of the axle beam (22 in Fig. 1) via a redundancy feature so that the operator of the vehicle may better maintain steering control. This redundancy feature is accomplished by the stop surface 106 of the shackle contacting the stop surface 72 of the shackle bracket. More specifically, in suspension configurations such as Fig. 1, where the shackle assembly 36a secures the trailing end of the leaf spring 12a to the frame rail 18a, the direction of forward travel will be as indicated by arrow 110. In the event that the leaf spring 12a breaks between the mounting location of the axle beam 22 and the frame hanger 16a, that is, the front limb of the leaf spring breaks, and the vehicle brakes are applied, the axle beam 22 will be urged to travel in the direction of arrow 112 with respect to the vehicle chassis, that is, rearwards towards the shackle assembly 36a. With reference to Fig. 7, this causes the leaf spring to be moved rearward with respect to frame rail 18a, which causes the shackle 40 to pivot counterclockwise about upper bar pin bushing 92, as indicated by arrow 113. As illustrated in Fig. 7, contact between the stop surface 106 of the shackle 40 and the stop surface 72 of the shackle bracket limits the counterclockwise travel of the shackle 40, and thus rearward travel of the leaf spring 18a and axle beam 22.

[0036] If the shackle assembly 36a is instead installed on the leading end of a leaf spring, and the rear limb of the leaf spring breaks, protection of a similar nature is provided if the vehicle is stopped while traveling in the reverse direction (i.e. opposite of the direction indicated by arrow 110 of Fig. 1).

[0037] As illustrated in Fig 7, the bridge portion 52 of the shackle may also be provided with a tab 114 having a stop surface 116 on an edge opposite the edge featuring tab 104 and stop surface 106. The stop surface 116 is not functional when the shackle is installed as illustrated in Fig. 7, but ensures that the redundancy feature is enabled when the shackled is installed in an inverted orientation. As a result, the shackle 40 may be installed with either end facing upward, and a shackle stop surface will be provided to engage the stop surface 72 of the shackle bracket.

[0038] It is to be understood that the tabs 104 and 114 of the bridge are provided for material savings purposes only. The stop surfaces 106 and 116 could instead be provided directly on edges of the bridge portion passing straight between the flanges 48a and 48b (i.e. tabs 104 and 114 omitted), or could otherwise be positioned anywhere on or within the bridge portion 52. [0039] As best shown in Fig. 2 and described above, a second stop surface 68 is provided on the shackle bracket 62. This enables the shackle bracket 62 to be installed on either side of the vehicle. Regardless of which side of the vehicle the shackle bracket 62 is installed on, a stop surface is provided to oppose the stop surface of the shackle secured to the shackle bracket. As a result, there is no need for an installer to inventory two different parts and the redundancy feature cannot inadvertently be omitted by installing a shackle bracket on the wrong side of the vehicle.

[0040] While the preferred embodiments of the disclosure have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made therein without departing from the spirit of the disclosure, the scope of which is defined by the following claims.

Claims

CLAIMS What is claimed is:

1. A shackle for mounting a suspension spring to a bracket secured to a frame of a vehicle comprising:

a. first and second wear plate portions;

b. first and second outer plate portions;

c. a first connector portion connecting the first wear plate portion to the first outer plate portion so that a first flange having a first fastener channel between the first wear plate portion and first outer plate portion is defined;

d. a second connector portion connecting the second wear plate portion to the second outer plate portion so that a second flange having a second fastener channel between the second wear plate portion and second outer plate portion is defined; e. said first flange including a first pair of spaced apart pin recesses;

f. said second flange including a second pair of spaced apart pin recesses that are aligned with the first pair of spaced apart pin recesses;

g. said first and second pair of pin recesses configured to receive an upper bar pin bushing attached to the bracket secured to the vehicle frame and a lower bar pin bushing attached to the suspension spring;

h. said first and second fastener channels configured to receive fasteners for securing the upper and lower bar pin bushings within the first and second pair of bar pin recesses;

i. a bridge portion connecting the first flange to the second flange, said bridge portion including a first stop surface configured to engage the bracket attached to the vehicle frame to limit pivoting of the shackle about an axis defined by the upper bar pin bushing.

2. The shackle of claim 1 wherein the first and second flanges and bridge portion are formed from a single piece of sheet metal.

3. The shackle of claim 1 wherein the bridge portion includes first and second side edges and further comprising a first tab positioned on the first side edge wherein the first stop surface is positioned on the first tab.

4. The shackle of claim 3 further comprising a second tab positioned on the second side edge of the bridge portion wherein the second stop surface is positioned on the second tab.

5. The shackle of claim 1 wherein the first pair of pin recesses are defined by notches formed in the first wear plate portion, the first outer plate portion and the first connector portion and wherein the second pair of pin recesses are defined by notches formed in the second wear plate portion, the second outer plate portion and the second connector portion.

6. A shackle assembly for mounting a suspension leaf spring having an eye portion to a frame of a vehicle comprising:

a. a shackle comprising:

i) a first flange having a first fastener channel and a first upper pin recess and a spaced apart first lower pin recess;

ii) a second flange having a second fastener channel and a second upper pin recess and a spaced apart second lower pin recess;

iii) a bridge portion connecting the first flange to the second flange, said bridge portion including a first shackle stop surface;

b. a shackle bracket configured to be attached to the vehicle frame, said shackle bracket including a bore and a first side including a first bracket stop surface; c. an upper bar pin bushing having a central portion positioned within the bore of the shackle bracket and first and second end portions positioned within the first and second upper pin recesses, respectively;

d. a lower bar pin bushing having a central portion positioned within the eye portion of the leaf spring and first and second end portions positioned within the first and second lower pin recesses, respectively; e. a first fastener positioned within the first fastener channel and securing the first ends of the upper and lower bar pin bushings within the first upper and lower pin recesses of the first flange;

f. a second fastener positioned within the second fastener channel and securing the second ends of the upper and lower bar pin bushings within the second upper and lower pin recesses of the second flange; and

g. said first shackle stop surface opposing the first bracket stop surface and configured to engage the first bracket stop surface to limit pivoting of the shackle about an axis defined by the upper bar pin bushing.

7. The shackle assembly of claim 6 wherein the first and second flanges and bridge portion are formed from a single piece of sheet metal.

8. The shackle assembly of claim 6 wherein the bridge portion includes first and second side edges and further comprising a first tab positioned on the first side edge wherein the first shackle stop surface is positioned on the first tab.

9. The shackle assembly of claim 8 further comprising a second tab positioned on the second side edge of the bridge portion wherein the second shackle stop surface is positioned on the second tab.

10. The shackle assembly of claim 6 wherein the first upper and lower pin recesses and the second upper and lower pin recesses are defined by notches formed in the first flange and notches formed in the second flange, respectively.

11. The shackle assembly of claim 6 wherein said shackle bracket further includes a second side including a second bracket stop surface.

12. The shackle assembly of claim 6 wherein the first end portion of the upper bar pin bushing and the first end portion of the lower bar pin bushing each includes a first circumferential groove that is engaged by the first fastener and the second end portion of the upper bar pin bushing and the second end portion of the lower bar pin bushing each includes a second circumferential groove that is engaged by the second fastener.

13. The shackle assembly of claim 6 wherein the first end portion of the upper bar pin bushing and the first end portion of the lower bar pin bushing each includes a first indentation that is engaged by the first fastener and the second end portion of the upper bar pin bushing and the second end portion of the lower bar pin bushing each includes a second indentation that is engaged by the second fastener.

14. The shackle assembly of claim 6 wherein the first and second fasteners each include a bolt and a nut configured to engage the bolt.

15. A suspension for supporting a vehicle frame on an axle comprising:

a. a leaf spring including a proximal end having a proximal eye portion, a distal end having a distal eye portion and a middle portion positioned between the proximal and distal ends configured to attach to the axle;

b. a frame hanger pivotally attached to the proximal eye portion of the leaf spring and configured to be attached to the vehicle frame;

c. a shackle comprising:

d. a shackle bracket configured to be attached to the vehicle frame, said shackle bracket including a bore and a first side including a first bracket stop surface; e. an upper bar pin bushing having a central portion positioned within the bore of the shackle bracket and first and second end portions positioned within the first and second upper pin recesses, respectively;

f. a lower bar pin bushing having a central portion positioned within the distal eye portion of the leaf spring and first and second end portions positioned within the first and second lower pin recesses, respectively;

g. a first fastener positioned within the first fastener channel and securing the first ends of the upper and lower bar pin bushings within the first upper and lower pin recesses of the first flange;

h. a second fastener positioned within the second fastener channel and securing the second ends of the upper and lower bar pin bushings within the second upper and lower pin recesses of the second flange; and

i. said first shackle stop surface opposing the first bracket stop surface and configured to engage the first bracket stop surface to limit pivoting of the shackle about an axis defined by the upper bar pin bushing.

16. The suspension of claim 15 wherein the bridge portion includes first and second side edges and further comprising a first tab positioned on the first side edge wherein the first shackle stop surface is positioned on the first tab.

17. The suspension of claim 16 further comprising a second tab positioned on the second side edge of the bridge portion wherein the second shackle stop surface is positioned on the second tab.

18. The suspension of claim 15 wherein the first upper and lower pin recesses and the second upper and lower pin recesses are defined by notches formed in the first flange and notches formed in the second flange, respectively.

19. The suspension of claim 15 wherein said shackle bracket further includes a second side including a second bracket stop surface.

20. The suspension of claim 15 wherein the first end portion of the upper bar pin bushing and the first end portion of the lower bar pin bushing each includes a first circumferential groove that is engaged by the first fastener and the second end portion of the upper bar pin bushing and the second end portion of the lower bar pin bushing each includes a second circumferential groove that is engaged by the second fastener.