Land vehicles – Body elevation or tilt – Loading position
Reexamination Certificate
1998-10-09
2001-07-10
Mai, Lanna (Department: 3619)
Land vehicles
Body elevation or tilt
Loading position
C280S124116, C280S124160, C280S754000, C280S764100, C280S086500
Reexamination Certificate
active
06257597
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an anti-creep device for use in a trailer suspension, and more specifically in a low-ride trailer suspension. The invention serves to retard the forward and downward movement of the trailer during loading, loss of air spring pressure, or other “stationary” times to limit the creep of the trailer from a loading dock or parked position.
2. Description of the Prior Art
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. In the loading or unloading of a low-ride trailer, the trailer is typically backed up against a dock by the tractor. The operator then pressurizes the air springs of the low-ride suspension so that the bed of the trailer is level with the loading dock. The operator then lowers the front dolly legs on the trailer until they touch the ground and then removes the tractor. In storage situations the tractor may or may not be connected to the trailer. Although the air springs are pressurized by the tractor's air compressor during transport and stationary times, the air compressor is normally off during loading or unloading operations.
As an empty trailer is loaded, the force from the weight of the goods being transferred to the trailer and the loading equipment, such as a forklift or a and car, 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 pivotable 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 wheel to move the trailer forward. In other words, the trailer tends to move away from the loading dock. This movement is referred to as “creep.” Trailer creep can create hazards for loading. This problem is augmented in low-ride trailers, since the air spring is pressurized to a greater height to compensate for the difference between the dock height and trailer bed height. The background and possible solutions to this problem can be found in PCT/US94/10789, which is herein incorporated by reference.
U.S. Pat. No. 5,333,645, issued Aug. 2, 1994, discloses an apparatus for overcoming trailer creep 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 creep associated with a trailer during loading. The anti-creep solution must also 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 normal operation thereof.
SUMMARY OF THE INVENTION
The invention relates to an anti-creep device for a trailer with a trailing arm suspension, and more especially for a low-ride trailer with a trailing arm suspension. It is simple, convenient and effective, and does not interfere with the normal operation of the trailing arm suspension during normal operation of the trailer. The anti-creep device is adapted for use in a trailing arm suspension comprising a trailing arm rotatably mounted at one of its ends to a trailer frame. At another end of the trailing arm, an air spring is disposed between the trailing arm and the trailer frame to resiliently resist the upward movement of the trailing arm with respect to the frame. An axle is mounted to the trailing arm and mounts a wheel. The anti-creep device comprises a pair of arms adapted to be rotatably mounted to the trailer frame at opposite ends thereof for movement between a retracted position and an extended position. In the extended position, the arms of the anti-creep device are adapted to extend between the frame and the suspension in order to prevent the movement of the axle with respect to the trailer frame and maintain the floor of the trailer level with the loading dock. In the retracted position, the arms are adapted to be disposed above the suspension so that the axle is free to move up and down through its normal range of motion under ordinary conditions.
The anti-creep device further includes an actuator adapted to be mounted between the trailer frame and the arms to control the movement of the arms between the retracted and extended positions. Preferably, the actuator is an air-operated actuator having a shaft adapted to mount to the arms so that the reciprocating movement of the shaft moves the arms between the retracted and extended positions.
In one embodiment, each arm comprises an elongated plate having one end adapted to be pivotally mounted to the trailer frame and having another end for contacting a load pad on the axle of the suspension when the elongated plate is in the extended position, preventing the upward movement of the axle with respect to the trailer frame. Preferably, the air actuator is adapted to be attached to a cross member, which forms part of the trailer frame. A drive cam is attached to the air actuator for rotating the arms of the anti-creep device.
In another embodiment, the anti-creep device comprises a pair of support arms that are adapted to be mounted at opposite sides of the trailer frame for rotational movement between a retracted position and an extended position. The support arms in the extended position are adapted to abut the axle at the opposite sides of the trailer frame to prevent movement of the axle toward the trailer frame and thereby prevent trailer frame creep. The support arms in the retracted position are disengaged from the axle so that the axle is free to move with respect to the frame. An actuator rod is adapted to extend between the opposite sides of the frame, and the pair of support arms are fixedly attached to opposite ends of the actuator rod for rotational movement therewith. An actuator is operably connected to the actuator rod for rotating the rod and thus the support arms between the retracted and extended positions.
According to another embodiment, an anti-creep device comprises a support arm adapted to be mounted to the trailer frame proximate to the axle for rotational movement between a retracted position and an extended position. The support arm includes a plurality of notches extending along a length thereof. A support member is adapted to be connected to the suspension and has at least one surface for receiving one of the support arm notches when the support arm is in the extended position to prevent movement of the axle toward the trailer frame and thereby prevent the trailer frame from creeping. The notches of the support arm in the retracted position are disengaged from the support member so that the axle is free to move with respect to the frame. An actuator is associated with the support arm for rotating the arm at least to the extended position to thereby lock the frame at a selected height when the frame is raised with respect to the axle.
Further according to the invention, a suspension for a vehicle includes a pair of trailing arms with a first end adapted to be rotatably mounted to opposite sides of a trailer frame, an air spring disposed on each trailing arm is adapted to be mounted to the trailer frame to resiliently resist the u
Holland Neway International, Inc.
Ilan Ruth
Mai Lanna
Rader, Fishman, Grauer & McGarry
LandOfFree
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