# Patent

## Title
Trailing arm suspension beam assembly

## Abstract

A suspension assembly includes an axle member, a first trailing beam assembly and a second trailing beam assembly. The first trailing beam assembly and the second trailing beam assembly each include a first end operably coupled to a vehicle frame and a second end that includes a downwardly opening recess, wherein the recess includes an outer periphery, the axle member is positioned within the recess, and wherein a weld extends about the entire periphery of the recess, thereby securing the trailing beams to the axle member.

## Background
BACKGROUND OF THE INVENTION
The present invention relates to an axle suspension system for heavy vehicles, and in particular to a trailing arm assembly with increased strength and which is adapted to increase the durability of an associated vehicle axle.
A variety of vehicle suspension systems utilizing air springs have been developed for use within semi-tractor trailer and other heavy duty vehicles. These systems control the relative position of the chassis with respect to an associated axle or axles and also to cushion the relative movement of the axle(s) toward the chassis frame. The suspension systems, and particularly the components such as the trailing arms and axle assemblies thereof, undergo significant stress during operation of the vehicle. Specifically, the connection between the trailing arms and the associated axle undergo significant stress when typical operational loads are exerted thereon, both in the vertical and lateral directions. While many systems have been developed to reduce such stress, previous approaches have been relatively expensive, and at times only marginally effective.
There is a need for a lightweight and inexpensive air spring suspension system that reduces the stress exerted between the trailing arms of the suspension system and the associated axle.



BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective view of a suspension system that includes a trailing arm assembly embodying the present invention;
FIG. 2 is a side elevational view of the suspension system, wherein a braking assembly has been removed to better illustrate the trailing arm assembly;
FIG. 3 is a perspective view of a first embodiment of the trailing arm assembly;
FIG. 4 is a side elevational view of the first embodiment of the trailing arm assembly;
FIG. 5 is a top plan view of the first embodiment of the trailing arm assembly;
FIG. 6 is a perspective view of end of the first embodiment of the trailing arm assembly;
FIG. 7A is an enlarged, partial perspective view of the suspension system, and in particular the trailing arm assembly;
FIG. 7B is an enlarged, partial perspective view of the suspension system, and in particular the trailing arm assembly;
FIG. 8 is an enlarged side elevational view of the first embodiment of the trailing arm assembly;
FIG. 9 is a perspective view of a second embodiment of the trailing arm beam assembly;
FIG. 10 is a perspective view of a trailing arm beam of the second embodiment of the trailing arm beam assembly;
FIG. 11a is a rear perspective view of a spring support member of the second embodiment of the trailing arm beam assembly;
FIG. 11b is a front perspective view of the spring support member of the second embodiment of the trailing arm beam assembly;
FIG. 12 is a perspective view of a third embodiment of the trailing arm assembly;
FIG. 13 is a side elevational view of the third embodiment of the trailing arm assembly;
FIG. 14 is a top plan view of the third embodiment of the trailing arm assembly;
FIG. 15 is a perspective view of a fourth embodiment of the trailing arm;
FIG. 16 is a side elevational view of the fourth embodiment of the trailing arm;
FIG. 17 is a partial cross-sectional top view of the fourth embodiment of the trailing arm taken along the line XVII-XVII, FIG. 16; and,
FIG. 18 is a top plan view of a plurality of a fourth embodiment of the trailing arm positioned within a rectangular casting core box.



DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in FIGS. 1 and 2. However, it is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.
The reference numeral 10 (FIGS. 1 and 2) generally designates a heavy duty vehicle suspension system that includes a plurality of trailing arm assemblies 12 each embodying the present invention. In the illustrated example, the vehicle suspension system 10 includes a pair of tandem axle assemblies including a forward axle assembly 14 and a rearward axle assembly 16, respectively. Each of the axle assemblies 14, 16 is supported by an associated trailing arm assembly 12. Each trailing arm assembly 12 includes a trailing arm or beam 18 having a first end 20 and a second end 21. The first end 20 is pivotally supported by an associated hanger bracket 22 that is fixedly attached to and extends downwardly from a longitudinally extending vehicle frame member 24. Specifically, the first end 20 of the hanger bracket 22 is pivotally coupled to the associated hanger bracket 22 via a bushing assembly 25 to pivot about a pivot axis 26. An air spring assembly 28 is positioned between an air spring support 30 of the trailing arm assembly 12 and the vehicle frame member 24.
As best illustrated in FIGS. 3-6, each trailing arm assembly 12 includes the trailing arm 18 and the air spring support 30. The trailing arm 18 includes a body portion 32 having a bushing aperture 34 located at the first end 20, and an axle adapter 36 located at the second end 21. The body portion 32 comprises a metal alloy, is preferably integrally cast as a single piece, and includes an I-shaped cross-sectional configuration including a vertical web portion 40, a bottom flange 42, and an upper flange 44.
The axle adapter 36 of the trailing arm 18 includes an outwardly, and specifically downwardly-opening, arcuately-shaped recess 46 that receives a vehicle axle 48 (FIGS. 7A, 7B) of the axle assembly 14, 16 therein. The axle adapter 36 further includes a pair of laterally extending forward weld ears 50 and a pair of laterally extending rearward weld ears 52. The recess 46 and the weld ears 50, 52 cooperate to define an axle seat periphery 54, about which the trailing arm 18 is welded to the associated axle 14, 16. In assembly, a single continuous weld 55 is preferably applied about the entire length of the axle seat periphery, thereby reducing the number of weld ends and increasing the durability of the axle connection. Specifically, welding about the entire axle seat periphery between the axle adapter 36 and the axle 48, reduces stress risers associated with using multiple welds, and allows a relatively thin axle wall to be utilized. As best illustrated in FIG. 8, the forward weld ears 50 and rearward weld ears 52 are positioned and configured with regards to the associated axle 14 such that the weld 55 positioned proximate a leading edge 65 of the forward weld ears 50 preferably forms a negative angle α with the horizontal of between about 30° to about 45°, and more preferably of about 35°, and such that the weld 55 positioned proximate a trailing edge 67 of the rearward weld ears 52 preferably forms a positive angle β the horizontal of between about 25° and about 45°, and more preferably of about 8°, thereby reducing the stress exerted on the axle connection by typical operational loads. The location of the weld ears 50, 52, and thus the associated welds, significantly reduces the stress swing exerted on the weld ears 50, 52 and the welds 55.
The air spring support 30 (FIGS. 3-6) of the trailing arm assembly 12 includes a top plate or spring support plate 56 upon which the associated air spring assembly 28 is supported, and a pair of support brackets 58 extending between the second end 21 of the trailing arm 18 and the top plate 56. Specifically, each support bracket 58 is generally triangularly shaped and includes a forward edge 60 weldably secured to a rearward face 61 of the second end 21 of the trailing beam 18, a top edge 62 weldably secured to an underside of the top plate 56, and a downwardly facing edge 64. The top plate 56 is positioned with respect to the support brackets 58 such that a forward edge portion 66 of the top plate 56 overlies the upper flange 44 of the trailing arm 18. The forward edge portion 66 includes a welding window 68 which receives a weld, thereby securing the top plate 56 to the trailing arm assembly 12. It is noted that the weld window 68 is located on an outboard side of the top plate 56 such that the top plate 56 is welded to a draft surface of the trailing arm 18, thereby causing the top plate 56 to “tilt” to the outboard side of the trailing arm 18. Specifically, the spring supporting surface 57 of the top plate 56 is outwardly canted with regards to at least one of the central axis member 39 and the central axis of the pivot axis 26 at an angle ∞ of preferably within the range of between about 0.5° and about 3°; and more preferably within the range of between about 0.5° and 1.5°. As a result, loading of the overall suspension system 10 causes the overall trailing arm assembly 12 to “tilt” inboard such that the top plate or air spring mounting plate 56 is substantially parallel to upper air spring mounting plates 70 (FIG. 1) attached to the frame member 24. The resulting parallel relationship between the top plate 56 and the associated upper air spring mounting plate 70 reduces the wear exerted on the air spring assembly 28 during operation.
The reference numeral 12a (FIGS. 9-11b) generally designates another embodiment of the trailing arm assembly of the present invention. Since the trailing arm assembly 12a is similar to the previously described embodiment of the trailing arm assembly 12, similar parts appearing in FIGS. 1-8 and FIGS. 9-11b respectively are represented by the same, corresponding reference numeral, except for the suffix “a” in the numerals of the latter. In the illustrated example, the trailing arm assembly 12a includes the trailing arm 18a and the air spring support 30a. The second end 21a of the trailing arm includes a pair of rearwardly extending eyelets or hinge members 100 having bolt-receiving apertures 102 extending therethrough. The air spring support 20a is generally arcuately-shaped and includes a forwardly-extending coupling portion 104 and a rearwardly-located spring support plate 56a. The coupling portion 104 includes a pair of laterally-spaced plate portions 106 that flank the hinge members 100 and include apertures 108 that correspond to the apertures 102 and that receive bolts 110, thereby coupling the air spring support 20a with the trailing arm member 18a. The end surface 111 of the trailing arm 18a is machined and abuts a machined surface 113 of the air spring support 30a, so as to support downward forces exerted by the air spring 28 onto the air spring support 30a. 
The reference numeral 12b (FIGS. 12-14) generally designates another embodiment of the trailing arm assembly of the present invention. Since the trailing arm assembly 12b is similar to the previously described embodiment of the trailing arm assembly 12, similar parts appearing in FIGS. 1-8 and FIGS. 12-14 respectively are represented by the same, corresponding reference numeral, except for the suffix “b” in the numerals of the latter. In the illustrated example, the trailing arm assembly 12b includes the trailing arm 18b and the air spring support 30b. The second end 21b of the trailing arm 18b is rearwardly, downwardly sloped and is defined by a rearward surface 80 and a ledge 82 that is vertically offset below an uppermost surface of the trailing arm 18b. The forward edge 60b of each of the support brackets 58b of the air spring support 30b has a forwardly-opening concave shape that is positioned about a complimentary convex shape of the rearward surface 80 of the trailing arm 18b. The forward edge portion 66b of the top plate 56b cantilevers and extends over the ledge 82 of the second end 21b of the trailing arm 18b and is secured thereto via a weld located within the welding window 68b. The air spring support 30b is further secured to the associated trailing arm 18b via welds 84, while the top plate 56b and the support brackets 58b are secured to one another via a plurality of welds 86. This particular configuration allows the overall height of the trailing arm assembly 12b to be minimized, and allows vertical loads from the air spring assemblies 28 to be supported by the trailing arm 18b through compressive stresses within the ledge 82 and rearward surface 80 of the trailing arm 18b. 
The reference numeral 18c (FIGS. 15-17) generally designates another embodiment of the trailing arm of the present invention. Since the trailing arm 18c is similar to the previously described embodiment of the trailing arm 18, similar parts appearing in FIGS. 3-6 and FIGS. 15-17 respectively are represented by the same, corresponding reference numeral, except for the suffix “c” in the numerals of the latter. As best illustrated in FIGS. 16 and 17, the overall height h defined between an uppermost portion of the recess 46c and the substantially perpendicularly located upper surface of the trailing arm 18c is reduced. This reduction in overall height is accomplished by providing a relatively thick portion 40c′ to the web portion 40c of the trailing arm 18c proximate the recess 46c, whereat the portion 40c of the web portion 40c has a relatively greater thickness t′′ compared to the thickness t′ of the web portion 40c extending along the remaining length of the trailing beam 18c. Preferably, the thickness t′′ is between 2 and 8 times greater than the thickness t′. It is noted that the trailing arm 18c does not include vertically extending reinforcement webs proximate to the forward edge of the recess 46c, thereby providing a reduction in the overall weight of the trailing arm 18c. 
The reference numeral 18d (FIG. 18) generally designates yet another embodiment of the trailing arm of the present invention. Since the trailing arm 18d is similar to the previously described embodiment of the trailing arm 18, similar parts appearing in FIGS. 3-6 and FIG. 18 respectively are represented by the same, corresponding reference numeral, except for the suffix “d” in the numerals of the latter. The trailing arm 18d is provided with an overall curvalinear body shape thereby allowing “nesting” of a plurality of trailing arms 18d with one another within an associated casting core box 88. The nesting of the trailing arms 18d with one another reduces the overall area required within the casting core box 88, thereby increasing yield per mold during the casting process, resulting in a reduction in costs for manufacturing each beam and increasing the overall efficiency of the foundry.
The present inventive trailing arm assembly and related suspension system increases the durability of the associated axle connection, while simultaneously reducing the weight. The trailing arm assembly and suspension system is efficient in assembly and use, is capable of a long operating life, and is particularly well adapted for the proposed use.
The above description is considered that of the preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the doctrine of equivalents.

## Claims

1. A suspension assembly, comprising:
an axle member having a central axis;
a first trailing beam assembly including a first trailing beam and a first spring support, the first trailing beam having a first end pivotably coupled to a vehicle frame about a first pivot axis and having a second end operably coupled to the axle member, the first spring support including a spring support plate having a spring supporting surface that is outwardly canted with respect to at least a select one of the central axis of the axle member and the first pivot axis prior to coupling the first trailing beam with the vehicle frame; and
a second trailing beam assembly including a second trailing beam and a second spring support, the second trailing beam having a first end pivotably coupled to a vehicle frame about a second pivot axis and having a second end operably coupled to the axle member, the second spring support including a spring support plate having a spring supporting surface that is outwardly canted with respect to at least a select one of the central axis of the axle member and the second pivot axis prior to coupling the second trailing beam with the vehicle frame.

2. The suspension assembly of claim 1, wherein the spring supporting surface of the first spring support is outwardly canted with respect to at least a select one of the central axis of the axle member and the first pivot axis within a range of from about 0.5° to about 3°, and wherein the spring supporting surface of the second spring support is outwardly canted with respect to at least a select one of the central axis of the axle member and the second pivot axis within a range of from about 0.5° to about 3°.

3. The suspension assembly of claim 2, wherein the spring supporting surface of the first spring support is outwardly canted with respect to at least a select one of the central axis of the axle member and the first pivot axis within the range of from about 0.5° to about 1.5°, and wherein the spring supporting surface of the second spring support is outwardly canted with respect to at least a select one of the central axis of the axle member and the second pivot axis within the range of from about 0.5° to about 1.5°.

4. A suspension assembly, comprising:
an axle member having a central axis;
a first trailing beam assembly, comprising:
a first trailing beam having a first end pivotably coupled to a vehicle frame about a first pivot axis, a second end operably coupled to the axle member, and an uppermost surface; and
a first spring support including a spring support plate having a spring supporting surface that is located vertically lower than the uppermost surface of the first trailing beam subsequent to the first trailing beam being coupled to the vehicle frame; and a second trailing beam assembly, comprising:
a second trailing beam having a first end pivotably coupled to the vehicle frame about a second pivot axis, a second end operably coupled to the axle member, and an uppermost surface; and
a second spring support including a spring support plate having a spring supporting surface that is located vertically lower than the uppermost surface of the second trailing beam subsequent to the second trailing beam being coupled to the vehicle frame.

5. The suspension assembly of claim 4, wherein the first trailing beam includes rearwardly extending coupling portion including an upper surface that is located below the uppermost surface of the first trailing beam, and wherein the spring support plate of the first spring support is fixedly secured to the rearwardly extending coupling portion to the first trailing beam.

6. The suspension assembly of claim 5, wherein the spring support plate of the first spring support includes an aperture extending therethrough that overlaps with the rearwardly extending coupling portion of the first trailing beam, and wherein the spring support plate of the first spring support is secured to the first trailing beam by a weld that extends at least partially about the aperture.

7. The suspension assembly of claim 4, wherein the first trailing beam includes a convex-shaped rearwardly extending surface, and wherein the first spring support includes a concave-shaped forwardly extending surface that receives the convex-shaped rearwardly extending surface of the first trailing beam when the first trailing beam is secured to the first spring support.