Spring devices – Vehicle – Comprising compressible fluid
Patent
1997-04-07
1999-07-13
Schwartz, Chris
Spring devices
Vehicle
Comprising compressible fluid
280DIG1, 267 6427, B60G 17005, F16F 904
Patent
active
059215321
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to air springs used in trailer suspensions, and more specifically to an improved air spring design in which an internal support member is selectively movable to retard movement of the ends of the air springs toward each other and thus limit suspension travel which will reduce trailer creep relative to a loading dock.
DESCRIPTION OF THE RELATED ART
In the loading of a trailer, the trailer is typically backed up against a dock by the tractor. The operator then lowers the front dolly legs on the trailer until they touch the ground and removes the tractor. In storage situations the tractor may or may not be connected to the trailer. Many trailers have trailing arm suspensions with air springs to control the relative position of the frame with respect to an axle and also to cushion the relative movement of the axle toward the frame due to bumps in the road. Although the air spring is pressurized by the tractor's air compressor during transport and stationary times, the air compressor is normally off during loading operation.
As the trailer is loaded, the force from the weight of the goods loaded into the trailer and the loading equipment, such as a forklift or a handcar, lowers the rear portion of the frame rail with respect to the axle. Because the compressor is off during the loading operation, the air pressure in the air spring is not adjusted to compensate for the increased load. While the rear portion of the trailer frame moves downwardly, the front portion of the trailer frame is substantially fixed at the height of the dolly and the trailer frame effectively rotates about the contact point of the dolly with the ground. The downward movement of the rear portion of the trailer frame results in the rotational movement of the pivotal connection between the trailer frame and the trailing arm. This pivotable movement results in the slight rotation of the trailing arm and wheel to move the trailer forward away from the dock In other words, the trailer tends to move away from the loading dock. This movement is referred to as "creep." Creeping of the trailer can create hazards for loading of the trailers.
U.S. Pat. No. 5,333,645, issued Aug. 2, 1994, discloses an apparatus for overcoming this problem by providing a dump valve to exhaust air from the air spring when the trailer door is opened. The trailer thus bottoms out on the suspension before loading begins and cannot creep away from the dock. Whereas this system has worked well to prevent creep, not all vehicles are equipped with this system, or cannot use such a system. Also, the door switch sometimes malfunctions and the dump valve does not always exhaust air from the air spring.
Therefore, there is a significant need to reduce or eliminate the creeping associated with a trailer during loading. Any solution must be simple, reliable and inexpensive if it is to be commercially viable. Further, the anti-creep solution must also not interfere with the normal function of the trailing arm suspension during its normal operation.
SUMMARY OF INVENTION
The invention relates to an air spring assembly comprising a top plate adapted for mounting to a vehicle frame, a piston adapted for mounting to a suspension, and a substantially hollow air bag mounted between the top plate and piston. During normal operation, the air bag is pressurized and the piston and top plate move toward and away from each other in response to forces acting on the suspension and vehicle frame. According to the invention, a support member is mounted inside the air bag for selective movement between first and second positions. In the first position, movement of the piston relative to the top plate is unrestricted in normal operation of the air spring. In the second position, the movement of the piston relative to the top plate toward each other is restricted. An actuator for moving the support member between the first and second positions is mounted to the support member and one of the top plate and piston.
In one embodiment, the support member c
REFERENCES:
patent: 1130656 (1915-03-01), Annable
patent: 3049362 (1962-08-01), Chambers
patent: 3074709 (1963-01-01), Ballard et al.
patent: 3077952 (1963-02-01), Neises
patent: 4375903 (1983-03-01), Lovell
patent: 4787606 (1988-11-01), Geno et al.
patent: 5201500 (1993-04-01), Ecktman et al.
patent: 5382006 (1995-01-01), Arnold
patent: 5413316 (1995-05-01), Easter
Douglass John Michael
Galazin Gregory T.
Greenzweig Daniel G.
Hicks William J.
Pierce William C.
Neway Anchorlok International, Inc.
Schwartz Chris
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