Spring devices – Vehicle – Bolster
Reexamination Certificate
1998-10-15
2001-04-24
Oberleitner, Robert J. (Department: 3613)
Spring devices
Vehicle
Bolster
C267S006000, C280S124175
Reexamination Certificate
active
06220580
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to bearings, and, more particularly, to bearings for leaf spring suspension systems.
BACKGROUND OF THE INVENTION
Heavy duty trucks such as large, tandem axle trucks commonly employ leaf spring suspension assemblies. A leaf spring suspension may include a plurality of stacked leaf springs. The springs are secured at their centers to the truck frame by means of a center post at a location between the axles. The springs extend from their centers to the respective axles in cantilever fashion. Typically, a pair of leaf spring suspension assemblies are used for each pair of axles with one leaf spring suspension assembly being positioned on either side of the truck. The ends of the springs may be connected to the axles by bearings. The bearing may include an elastomeric member configured and positioned to allow relative movement between the spring and the associated axle to prevent damage to the spring or undue limitation of the axle travel. Examples of such elastomer bearings may be found in U.S. Pat. Nos. 5,676,356, 5,020,824, 4,322,061, 3,099,459, 2,929,618, and 2,831,674.
In a leaf spring suspension assembly as described above, the wheels, axles and springs may undergo a wide range and variety of deflections and combinations of deflections in use. For example, when the truck is traveling over rough terrain or curbs, the wheels and, thus, the adjacent axles, may move independently and through large degrees of displacement. If a wheel on one end of an axle is displaced upwardly while the wheel on the opposite end of the axle is displaced downwardly, the axle will pivot and thereby induce a conical torsional load which tends to twist the leaf springs. Moreover, if one wheel is displaced upwardly and the adjacent wheel (on the adjacent axle) is displaced downwardly, the respective axles will pivot in opposite directions and thereby induce a torsional load which tends to conically deflect the respective ends of the leaf springs in opposite directions. As a wheel travels vertically upwardly or downwardly and flexes the leaf spring assembly beyond its neutral position, the vertical angle between the leaf spring end and the axle is changed, thereby inducing a localized load on the end of the spring which may tend to bend the leaf springs. One end of the wheel may also be displaced laterally so that the wheel is rotated about a vertical axis, again inducing a torsional load on the spring.
It is important that such deflections and combinations of deflections not result in damage to the leaf spring assembly. It is also important that the leaf spring suspension and the components thereof be durable and not negatively affect the handling of the vehicle.
One problem encountered with multiple or tandem axle vehicles is that a misalignment of the axles may cause significant wear damage to the tires and other components. Moreover, misalignment may degrade the handling of the vehicle. Typically, the relative alignment of the axles is established at the factory during manufacture of the truck. It is not uncommon for the axles to become misaligned thereafter as a result of impacts in use or improper replacement or repair of components of the suspension and drive train.
Thus, there exists a need for a means for accommodating the various pivotal loads applied between an axle and a leaf spring assembly. Such means should not negatively affect the operability or handling of the vehicle. Such means should be durable. Moreover, there is a need for means for conveniently and effectively adjusting alignment between axles of a tandem axle vehicle, particularly of the type employing a leaf spring suspension.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
SUMMARY OF THE INVENTION
The present invention is a leaf spring suspension assembly and bearings therefor which accommodates various pivotal loads applied between an axle and a leaf spring assembly. The leaf spring suspension assembly does not negatively affect the operability and handling of a vehicle, is durable, and provides improved service life. In another aspect, the present invention provides means for conveniently and effectively adjusting alignment between axles of a tandem axle vehicle. According to another aspect of the present invention, a bearing is provided for a leaf spring suspension assembly which allows convenient replacement of the working parts thereof.
In more detail, the present invention is directed to a bonded bearing, a bearing assembly, and a leaf spring suspension assembly each including a bonded elastomer member. The bonded bearing, the bearing assembly and the leaf spring suspension assembly may be used for tandem axle vehicles or the like, for example. The bonded bearing, the bearing assembly, and the leaf spring suspension assembly each provide improved isolation of a leaf spring assembly from pivotal/torsional loads caused by movements of an associated axle, for example. Furthermore, the bonded bearing, the bearing assembly, and the leaf spring suspension assembly each provide improved durability, service life and convenience of installation and maintenance.
The leaf spring suspension assembly includes a leaf spring assembly including a plurality of vertically stacked leaf springs. A bearing assembly is positioned adjacent the leaf spring assembly. The bearing assembly includes an upper insulator cup, a lower bracket cap and upper and lower bonded bearings. The upper insulator cup includes an upper recess and the upper bonded bearing is received in the upper recess. The upper bonded bearing includes a rigid lower member received adjacent an upper side of the leaf spring assembly. An upper elastomer element is bonded to the rigid lower member. The lower bonded bearing is received in the lower recess. The lower bonded bearing includes a rigid upper member received adjacent a lower side of the leaf spring assembly. A lower elastomer element is bonded to the rigid upper member. At least one, and preferably both, of said upper and lower elastomer elements comprises a spherical elastomer element.
Preferably, at least one of the upper and lower elastomer elements includes at least two elastomer layers and a shim interposed between the elastomer layers. Means may be provided for compressing the upper elastomer element between the upper insulator cup and the rigid lower member and for compressing the lower elastomer element between the lower bracket cap and the rigid upper member.
According to another aspect, the elastomer bearing assembly according to the present invention may be used with a leaf spring assembly and includes an upper insulator cup having an upper planar recess and a lower bracket cap having a lower spherical recess. An upper bonded bearing is received in the upper planar recess. The upper bearing includes a rigid lower member having a first pilot and a spherical surface and an upper elastomer element bonded to the spherical surface. The upper elastomer element includes a plurality of spherical elastomer layers. The first pilot is adapted to be received adjacent to the leaf spring assembly. A lower bonded bearing is received in the lower recess. The lower bonded bearing includes a rigid upper member having a second pilot and a spherical surface and a lower elastomer element is bonded to the spherical surface. The lower elastomer element also includes a plurality of spherical layers. The second pilot is adapted to be received adjacent to the leaf spring assembly.
The present invention is further directed to an elastomer bearing assembly for use with an associated leaf spring assembly. The bearing assembly includes an insulator cup having a first recess and a bracket cap having a second recess. A first bonded bearing is received in the first recess, the first bonded bearing inc
Gnibus Michael M.
Lord Corporation
Oberleitner Robert J.
Rodriguez Pan
Wayland Randall S.
LandOfFree
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