TECHNICAL FIELD

This document relates generally to the trailer equipment field and, more particularly, to a new and improved tandem axle suspension system. That tandem axle suspension system includes a fixed center keeper that holds the slipper ends of two slipper springs.

BACKGROUND

FIG. 1illustrates a prior art suspension system SS which includes an equalizer A that is pivotally mounted to the center hanger B of the trailer frame C and connected to the first spring D and second spring E by means of two shackles F, G. The same structure is also provided on the opposite side of the trailer.

This construction includes a total of ten moving parts and ten bolts that connect those parts. The ten moving parts and the ten bolts that connect them are lubricated by soft plastic bushings with a useful life of as little as 1,000 miles. When these bushings fail, the entire suspension begins to self-destruct with steel on steel friction grinding the components into failure.

In addition to the poor durability noted above which requires frequent and expensive maintenance, prior art suspensions of the type illustrated inFIG. 1suffers from a number of additional drawbacks. Most lack suspension alignment capability. They fail to provide for control of spring rebound and compression energy. Further, they suffer from diminished tire traction during hard or panic braking due to a condition referred to as “axle roll up.” More specifically, panic braking causes a sudden rearward rotation of the forward axle H. This rotation forces the equalizer A to severely rotate rearward and partially lift the rear tires I from the pavement J thereby reducing braking traction with the road surface.

The new and improved suspension system described in this document addresses and solves all of these shortcomings of the prior art suspension system SS noted above.

SUMMARY

In accordance with the purposes and benefits described herein, a new and improved tandem axle suspension assembly is provided. That tandem axle suspension assembly comprises a first slipper spring, having a first eye and a first slipper end, and a second slipper spring having a second eye and a second slipper end. The first slipper spring and the second slipper spring are provided in series with the first slipper end and the second slipper end oriented toward each other.

The tandem axle suspension assembly may further include a keeper receiving the first slipper end and the second slipper end. The keeper may include a first frame support that rides on the first slipper end and a second frame support that rides on the second slipper end. That first frame support may include a first roller bearing. That second frame support may include a second roller bearing.

The first frame support of the tandem axle suspension assembly may include a first roller bearing bolt. The first roller bearing may be received around that first roller bearing bolt. Similarly, the second frame support of the tandem axle suspension assembly may include a second bearing bolt. The second roller bearing may be received around that second roller bearing bolt.

The keeper of the tandem axle suspension assembly may include a housing. That housing may have a u-shaped cross-section. Further, the housing may include a receiver that receives a center hanger on a frame of a trailer to which the tandem axle suspension assembly is attached.

Still further, the housing may be described as including a center section, a first end section and a second end section. The first end section and the second end section both depend from the center section. The receiver may be provided in the center section between the first end section and the second end section.

The tandem axle suspension assembly may further include a mounting bolt extending through a first mounting receiver in the first end section, a second mounting receiver in the second end section and a third mounting receiver in the center hanger.

The keeper of the tandem axle suspension system may include a first spring retainer bolt. The first slipper end may be captured between the first spring retainer bolt and the first roller bearing. The keeper may also include a second spring retainer bolt. The second slipper end may be captured between the second spring retainer bolt and the second roller bearing.

In accordance with an additional aspect, a new and improved keeper is provided for a tandem axle suspension assembly. That keeper comprises a housing including: (a) a first set of receivers including a first spring retainer receiver, a second spring retainer receiver, a first roller bearing mounting receiver, a second roller bearing mounting receiver and (b) a second set of receivers including a third spring retainer receiver, a fourth spring retainer receiver, a third roller bearing mounting receiver and a fourth roller bearing mounting receiver.

The keeper may further include a third set of receivers for mounting a first shock. That third set of mounting receivers may include a first shock mounting receiver, a second shock mounting receiver, a third shock mounting receiver and a fourth shock mounting receiver. Still further, the keeper may also include a fourth set of receivers for mounting a second shock. The fourth set of mounting receivers may include a fifth shock mounting receiver, a sixth shock mounting receiver, a seventh shock mounting receiver and an eighth shock mounting receiver.

The first roller bearing mounting receiver may be provided between the first shock mounting receiver and the second shock mounting receiver. The second roller bearing mounting receiver may be provided between the third shock mounting receiver and the fourth shock mounting receiver. The third roller bearing receiver may be provided between the fifth shock mounting receiver and the sixth shock mounting receiver. The fourth roller bearing mounting receiver may be provided between the seventh shock mounting receiver and the eighth shock mounting receiver.

In the following description, there are shown and described several preferred embodiments of the new and improved tandem axle suspension system. As it should be realized, the system is capable of other, different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the system as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive.

