Land vehicles – Body elevation or tilt – Loading position
Reexamination Certificate
1999-04-09
2001-03-13
Rice, Kenneth R. (Department: 3611)
Land vehicles
Body elevation or tilt
Loading position
C280S086500
Reexamination Certificate
active
06199876
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to vehicle suspension systems. More particularly, this invention relates to a system for stabilizing a suspension system under selected conditions.
A variety of suspension systems are available for passenger and heavy duty vehicles. One type of suspension provided for heavy duty vehicles is air-based and includes the ability to adjust the position of an axle on a truck trailer. These suspensions are particularly useful for truck trailers that are optionally made into trains and transported by railway. When such a truck trailer is utilized for driving along the highway, for example, the suspension is adjusted into a first position where the wheels are spaced from the underside of the trailer a sufficient distance for driving along the road. When the trailer is to be transported by train, however, the suspension is adjusted so that the wheels are in a relatively retracted position, closer to the underside of the trailer. Since the wheels need to be adjusted into the two different positions, the suspension system must be adjustable to accommodate movement of the wheel axle between the two positions.
While such systems have proven useful and advantageous, they are not without shortcomings and drawbacks. For example, since the suspension system must accommodate movement of the axle between two relatively extreme positions, there is a requirement for a large amount of resiliency in the suspension system. This resiliency can pose problems under certain conditions.
For example, when loading a trailer, it is common to drive a lift truck onto the trailer bed. Because the lift truck is typically very heavy, a large load is rapidly imposed on the suspension system, which cannot react quick enough to avoid having the trailer bed drop suddenly as a result of the weight of the lift truck. This poses at least two problems. First, this provides undesirable wear on the trailer suspension components. Second, when the trailer is at a docking station, for example, it is necessary to maintain the truck bed at a height that enables a worker to easily move between the truck bed and the loading dock. When the truck bed drops because the air-based suspension system cannot accommodate the weight of a lift truck, for example, it may not be possible to drive the lift truck off of the trailer bed back onto the loading dock. In some instances, the air-based suspension system is not capable of being adjusted sufficient to raise the trailer bed back to a height consistent with the loading dock.
Additionally, when a lift truck is driven off of a trailer bed, the trailer bed often bounces upward in response to the force that is provided by the air-based suspension system, which has been under high pressure in an attempt to counteract the weight of the lift truck. Since the suspension system is provided with enough air to support the weight of the lift truck, when the lift truck leaves the trailer bed, the system is not able to adjust quickly enough to avoid the trailer bed being bounced upward. This undesirably increases the wear on the suspension components and can pose problems to the cargo that is loaded onto the trailer bed.
Therefore, there is a need for an improved suspension system that can be stabilized to avoid the shortcomings and drawbacks discussed above while still permitting the suspension system to be adjusted into the positions necessary to accommodate driving along a highway or being transported by railway. This invention addresses those needs by providing an improved suspension system.
SUMMARY OF THE INVENTION
In general terms, this invention is a vehicle suspension system that is selectively adjustable to provide stability during loading or unloading operations and to allow the suspension to be adjustable to accommodate different transportation scenarios.
A system designed according to this invention includes several basic components. An axle is provided to support wheels for the vehicle in a conventional manner. A suspension beam is associated with the axle and has at least one end that is moveable relative to the body of the vehicle so that the position of the axle relative to the body of the vehicle is adjustable. An adjustable support has a first end supported adjacent the body of the vehicle. A second end of the adjustable support is selectively moveable relative to the first end. The second end of the support preferably is received by a receiver portion on the suspension beam. The adjustable support controls a distance between the moveable end of the suspension beam and the vehicle body so that the distance between the vehicle body and the wheels is controlled. The adjustable support is selectively locked to maintain a fixed distance between the moveable end of the suspension beam and the vehicle body.
In the preferred embodiment, the adjustable support is hydraulic. A hydraulic version of the adjustable support preferably includes a housing at the first end of the support and a moveable shaft at the second end. The hydraulic support is adjusted so that the moveable shaft moves relative to the housing to adjust a distance between the first and second ends of the support. The receiver portion on the suspension beam preferably receives a terminal portion of the moveable shaft when the moveable shaft is moved appropriately.
The adjustable support can be used to stabilize a trailer bed during loading or unloading operations and provides the additional advantage of assisting an air-based suspension system to lift a trailer bed to a desired height.
Further details and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.
REFERENCES:
patent: 1175545 (1916-03-01), Morgan
patent: 4568094 (1986-02-01), Lovell
patent: 5340141 (1994-08-01), Thorndyke
Carlson & Gaskey & Olds
Meritor Heavy Vehicle System, LLC
Rice Kenneth R.
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