WO1996009179A1

WO1996009179A1 - Anti-creep device

Info

Publication number: WO1996009179A1
Application number: PCT/US1994/010789
Authority: WO
Inventors: Gregory A. Richardson; Lyle M. Hagan
Original assignee: Nai Neway, Inc.
Priority date: 1994-09-22
Filing date: 1994-09-22
Publication date: 1996-03-28
Also published as: AU1253295A

Abstract

An anti-creep device for trailers comprising a rotatable member (54, 102, 206, 302) mounted to the trailer frame and adapted to be movable between a retracted position and an extended position. In the retracted position, the axle (16) and wheel (18) of the trailer are free to move within the limits of the suspension. In the extended position, the rotatable member limits the relative movement between the trailer frame and the suspension to limit creep of the trailer.

Description

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Background of the Invention Field of the Invention

The invention relates to an anti-creep device for use in a trailer suspension to retard the forward and downward movement of the trailer upon loading, loss of air spring pressure or other events causing a change in axle to frame relationship, and more specifically to a device for limiting the relative downward movement of the vehicle frame with respect to the axle of the trailer suspension during loading or other "stationary" times to limit the creep of the trailer from a loading dock or parked position.

Description of the Prior 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 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 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. Patent No. 5,333,645, issued August 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. The anti-creeping 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 Invention The invention relates to an anti-creep device for a 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 an arm adapted to be rotatably mounted to the trailer frame for movement between a retracted position and an extended position. In the retracted position, the arm is 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. In the extended position, the end of the arm is adapted to abut a portion of the suspension to restrict the downward movement of the frame with respect to the axle in order to prevent creep of the trailer frame away from a loading dock when loaded at least when the end of the arm abuts the portion of the suspension.

The anti-creep device can further include an actuator adapted to be mounted to the vehicle frame and the arm to control the movement of the arm between the retracted and extended positions. Preferably, the actuator is an air-operated brake actuator having a shaft adapted to mount to the arm so that the reciprocating movement of the shaft moves the arm between the retracted and extended positions. The arm of the anti-creep device can abut the trailing arm or the axle or the axle attachment brackets to prevent the movement of the axle with respect to the trailer frame.

In one embodiment, the arm is U-shaped with two opposing side members connected by a base member. The side members are adapted to be rotatably mounted to the trailer frame and the base member is adapted to abut the trailing arm when the arm is in the extended position. An elastomeric pad can be mounted to the base member so that the elastomeric pad abuts the trailing arm when the arm is in the extended position.

In a second embodiment, the arm is an elongated plate having one end adapted to be pivotally mounted to the trailer frame and having another end with a recess in which the axle of the suspension is received when the elongated plate is in the extended position, preventing the upward movement of the axle with respect to the trailer frame. Preferably, the elongated plate is rotatably mounted to a cross member, which forms part of the trailer frame.

In a third embodiment, the arm is a first plate, immovably mounted to the trailer frame, and a second plate, rotatably mounted to the first plate by a hinge. The second plate can rotate about the hinge to move the second plate between the retracted position and the extended position.

In a fourth embodiment, the arm is a hook pivotally mounted to the trailer frame for movement between the retracted position and the extended position where the hook is disposed above a bracket mounted to the trailing arm. Brief Description of the Drawings

The invention will now be described with reference to the drawings wherein:

FIG. 1 is a side view of a trailing arm suspension incorporating Applicant's anti-creep device according to the invention;

FIG. 2 is a side view of the trailing arm suspension shown in FIG. 1, with the anti-creep device in an extended position;

FIG. 3 is a sectional view along line 3-3 of FIG. 2; FIG. 4 is a side view, like FIG. 2, illustrating a second embodiment of an anti-creep device according to the invention in an operative position;

FIG. 5 is a side view, like FIG. 1, illustrating a third embodiment of an anti-creep apparatus according to the invention;

FIG. 6 is a side view, like FIG. 2, illustrating a fourth embodiment of an anti-creep device according to the invention in an operative position; and

FIG. 7 is an end view of the fourth embodiment along line 7-7 of FIG. 6.

Description of the Preferred Embodiments Figure 1 illustrates a trailing arm suspension 10 incorporating the anti-creep device 12 according to the invention. The trailing arm suspension 10 is mounted to a longitudinal frame rail 14 of a trailer frame and supports an axle 16 to which wheels 18 are mounted on opposite ends of the axle 16. In a typical trailer application, two trailing arms are used to mount the axle 16 to the frame rail 14. The trailing arms are mounted on opposite sides of the frame rail and support opposing ends of the axle 16. Only one of the trailing arms will be described in detail.

The trailing arm suspension 10 comprises a hanger bracket 22 fixedly mounted to the frame rail 14 and to which is rotatably mounted a trailing arm 24 by means of a bushed connection 26 at the forward end of the trailing arm 24. The rearward end of the trailing arm 24 mounts an air spring 30 at a lower end thereof, which is connected to the frame rail 14 at its upper end. The air spring 30 resiliently resists upward movement of the trailing arm 24 with respect to the frame and comprises an air bag 32 mounted to the frame rail 14 and a piston 34 mounted to a platform 36 on the trailing edge of the trailing arm 24. As the trailing arm 24 rotates, the piston 34 is urged into the air bag 32 to resiliently retard movement of the trailing arm 24 toward the frame rail 14.

The axle 16 is mounted to the trailing arm 24 by an axle mounting bracket 40 having opposing plates 41, which are connected to the trailing arm 24 through two bushed connections 42 and 44. A shock absorber 46 can be mounted between the frame rail 14 and the axle bracket 40 to dampen the movement of the trailing arm 24 with respect to the frame.

Referring to FIGS. 1-3, the anti-creep device 12 comprises a brake actuator 50 having a reciprocating shaft 52, with a clevis 53 pivotally mounted to a generally U-shaped arm stop 54, which is pivotally mounted to the frame rail 14 through a bolt 80. The brake actuator 50 is a well-known device used to actuate air brakes. Suitable brake actuators are sold by NAI Anchorlok, of Muskegon, Michigan. It has an air port 59 that is in fluid communication with an internal chamber (not shown). The air port 59 is also fluidly connected to a pressurized air source (not shown). Upon the filling of the internal chamber with pressurized air through the air port 59, the pressurized air overcomes a force of a spring (not shown) disposed within the chamber and extends the shaft 52 out of the brake housing as shown in FIG. 1. Upon exhausting air from the air port 59, the internal spring retracts the shaft 52 into the internal chamber to the position shown in FIG. 2. The arm stop 54 is generally U-shaped and comprises channel members 60 and 62 connected at their lower ends by a plate 64. A rubber pad 66 is mounted to the plate 64 and provides a surface for evenly distributing the load from the arm stop 54 across the uneven surface of the trailing arm 24.

The channel members 60 and 62 are formed from channel or U- shaped members having a central web 70 from which extend side flanges 72 and 74. Each of the central webs 70 has an aperture (not shown) through which the bolt 80 passes. A cylindrical tube 78 retains a grease fitting (not shown) and in combination with the bolt 80 rotatably mounts the arm stop 54 to the frame rail 14. The cylindrical tube extends between the webs 70 and passes through the frame rail 14. The grease fitting and the bolt 80 are conventional. Any other suitable device or method can rotatably mount the arm stop 54 to the frame rail 24. One of the channel members 60 and 62 has a lateral flange 86 mounted to an upper end thereof and from which extends a mounting flange 88. A pin 92 passes through an aperture in the clevis 53 to attach the end of the emergency brake actuator shaft 52 to the arm stop 54. The reciprocation of the shaft 52 by the pressurization and exhaustion of air from the brake actuator 50 pivots the arm stop 54 about a longitudinal axis of the cylindrical tube 78 and bolt 80 between the retracted position (FIG. 1) and the extended position (FIG. 2) as a result of the pivotal connection of the shaft 52 of the brake actuator 50 to the connecting flange 84 of the arm stop 54. In the extended position, the rubberized pad is positioned slightly above the trailing arm 24 to prohibit the locking of the trailing arm 24 and arm stop 54.

When the anti-creep device 12 is deactivated, the shaft 52 of the emergency brake actuator 50 holds the arm stop 54 in the raised position as illustrated in FIG. 1. When the anti-creep device 12 is in the activated position, the shaft 52 of the emergency brake actuator 50 is withdrawn and retains the arm stop 54 in an extended position as illustrated in FIG. 2. In the extended position, the arm stop 54 limits the relative movement between the frame rail 14 and the trailing arm 24.

In operation, as the trailer is being pulled by the tractor, the emergency brake actuator 50 is pressurized by air which enters the air port 59 and the arm stop 54 is held in the retracted position (FIG. 1) by the extended shaft 52. With the arm stop 54 in the retracted position, the trailer is backed into a loading dock area so that the end of the trailer abuts the end of the loading dock. The air is then exhausted from the brake actuator 50 and the shaft 52 is retracted, thereby pivoting the arm stop 54 about the longitudinal axis of the cylindrical tube 78 and bolt 80 to rotate the arm stop 54 to the extended position (FIG. 2).

As the uncoupled trailer is loaded, the weight placed on the frame rail 14 by loading devices, such as hand carts and forklifts, and the goods that are carried on the loading devices lower the frame rail 14. As the frame rail drops, the pad 66 of the arm stop 54 moves towards the trailing arm 24. Once the arm stop 54 contacts the trailing arm 24, the frame rail 14 is prevented from moving downwardly with respect to the trailing arm 24 and thus prevents creeping of the trailer away from the dock.

When the trailer is loaded, the air supply is turned on again and the air spring is again pressurized to raise the frame rail 14 to a design height, thereby lifting the arm stop 54 out of contact with the trailing arm 24. The brake actuator 50 is again pressurized to retract the shaft 52 and move the arm stop 54 to the retracted position.

FIG. 4 illustrates a second embodiment 100 of an anti-creep device according to the invention. The second embodiment 100, like the first embodiment, is used in combination with a trailing arm suspension. Therefore, like numerals will identify like parts in the trailing arm suspension of both the first and second embodiments of the anti-creep device. All parts directed to the second embodiment 100 of the anti-creep device will begin with the numeral 100.

The anti-creep device 100 comprises an axle stop 102, which is pivotally mounted to a support bracket 104 by a pin 106. The lower end of the axle stop 102 is cut away to define a recess 110, which substantially conforms to the shape of the axle 16, and an arm 112. The shaft 52 of the emergency brake actuator 50 is pivotally connected to the axle stop 102. The support bracket 104 is welded to a cross-member 108 mounted to the frame rail 14. Alternatively, the support bracket 104 can be welded directly to the outside face of the frame rail and eliminate the need for a cross-member 108.

In operation, the axle stop 102 is maintained in a retracted position (as illustrated by the phantom lines in FIG. 4) substantially parallel to the frame rail 14 by the brake actuator shaft 52. The introduction of pressurized air into the brake actuator 50, extends the shaft 52 outwardly of the brake housing to rotate the axle stop 102 about a longitudinal axis of the pin 106 to position the axle stop 102 substantially parallel to the frame rail 14. To actuate the anti-creep device 100, the pressurized air is exhausted from the emergency brake actuator 50 to move the shaft 52 inwardly and to rotate the axle stop 102 dowwardly. The axle stop 102 continues rotating downwardly until the arm 112 contacts the axle 16. Upon the loading of the trailer, the weight of the loading devices and their goods moves the frame rail 14 down with respect to the trailing arm 24 until the axle 16 contacts the recessed surface 110 of the axle stop 102. The rotation and the creeping of the trailer away from the dock is prevented upon the contact of the axle 16 by the recessed surface 110.

FIG. 5 illustrates a third embodiment 200 of the anti-creep device according to the invention. Like the first and second embodiments, the third embodiment is illustrated in the context of a trailing arm suspension 10.

Like numerals will be used to identify like parts of the trailing arm suspension 10. The third embodiment 200 of the anti-creep device will be identified with numerals beginning with 200.

The anti-creep device 200 comprises a mounting plate 202 welded or bolted to the frame rail 14 and to which is fixedly mounted a hinge plate 204. A hinge arm 206 is rotatably mounted to the hinge plate 204 by a hinge 208 and can rotate about the hinge 208 from an extended position (FIG. 5), where its end is disposed slightly above the trailing arm 24, to a retracted position (as shown by phantom lines in FIG. 5), where it is moved toward the frame rail 14.

The hinge arm 206 has a mounting flange 210 to which one end of air cylinder 212 is rotatably mounted. The other end of the air cylinder 212 is rotatably mounted to the mounting plate 202. The air cylinder 212 has a fixed tubular portion 214 from which extends a reciprocating shaft 216. The reciprocating shaft 216 is connected to a piston (not shown) within the tubular portion 214. A spring (not shown) is disposed within the tubular portion and biases the shaft 216 away from the tubular portion 214. The air cylinder 212 is adapted to receive pressurized air from an air source so that when the trailer is connected to the air source, the pressurized air overcomes the spring force of the spring in the tubular portion 214 to compress the spring and retract the shaft 216. When the air cylinder is uncoupled from the air source, the spring force extends the shaft 216. In operation, the hinge arm 206 is initially in the retracted position (as illustrated by phantom lines in FIG. 5). When the air cylinder 206 is disconnected from the air supply, the shaft 216 extends from the tube portion 214 to rotate the hinge arm 206 downwardly to the extended position. As the trailer is loaded, the hinge arm 206 abuts the trailing arm 24 to prevent creep of the trailer from the loading dock.

FIGS. 6 and 7 illustrate a fourth embodiment 300 of the anti- creep device according to the invention. Like the first, second and third embodiments, the fourth embodiment is illustrated in the context of a trailing arm suspension 10. Like numerals will be used to identify like parts of the trailing arm suspension 10. The fourth embodiment 300 of the anti-creep device will be identified with numerals beginning with 300.

The anti-creep device 300 comprises a J-shaped arm 302 having a shank portion 304 and a hook portion 306. The shank 304 is pivotally mounted to the frame rail 14 at a location between the end of the shank and the hook 306. The shaft 52 of the brake actuator 50 is pivotally mounted to the shank 304 of the arm 302 at a portion of the shank 304 above the pivotal mounting 308.

A stop bracket 314 comprises a top plate 316 with an opposing bottom plate 318 connected by tapered end plates 320 and 322. The top plate

316, bottom plate 318 and end plates 320 and 322 define an open-ended chamber 324 in which the hook 306 of the arm 302 is received when the arm is in the extended position. The stop bracket 314 is mounted to the trailing arm suspension 10 by positioning the top plate 316 above an air spring mounting plate 328 of the trailing arm suspension 10 and below the piston 34 of the air spring 30.

In operation, the J-shaped arm 302 is initially disposed in the retracted position (as illustrated by the phantom lines in FIG. 6) during the normal operation of the trailer. In this condition, the trailing arm is free to move vertically about the bushed connection 26. In preparing to load the trailer, the trailer is backed into the dock and the air is exhausted from the emergency brake system, causing the shaft 52 of the brake actuator 50 to extend and rotate the shank 304 of the arm 302 about the pivot 308. As the shank is rotated about the pivot 308, the hook 306 moves into the chamber 324 of the stop bracket 314, as illustrated in FIG. 6. When the hook is moved into the chamber 324 of the stop bracket 314, it is in the extended position and the bottom edge of the hook 306 is disposed slightly above the bottom plate 318 of the stop bracket 314 to prevent binding of the arm 302 with respect to the stop bracket 314 after the trailer is loaded.

As the trailer is loaded, there is relative movement between the frame rail 14 and the trailing arm 24 and the bottom edge of the hook 306 abuts the bottom plate 318 to prevent further relative movement of the frame rail 14 with respect to the trailing arm 24. Upon limiting the relative movement of the frame rail 14 to the trailing arm 24, the fourth embodiment of the anti-creep device prevents further creeping of the trailer.

Once the trailer is loaded, the air is connected to the air springs to inflate the air bag 32 and raise the frame rail 14 with respect to the trailing arm 24 to move the hook 306 out of contact with the bottom plate 318. The emergency brake air system is then reconnected so that the shaft 52 of the brake actuator 50 is retracted and pivots the arm 302 about the pivot 308 to remove the hook 306 from the chamber 324.

The anti-creep device according to the invention provides a simple and reliable solution to the trailer creep problem. The anti-creep device also can be installed as original equipment or a retro-fit.

While particular embodiments of the invention have been shown, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. Reasonable variation and modification are possible within the scope of the foregoing disclosure of the invention without departing from the spirit of the invention.

Claims

ClaimsThe embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An anti-creep device for a trailer having a trailing arm suspension comprising a trailing arm rotatably mounted at one end to a trailer frame, an air spring mounted between another end of the trailing arm and the trailer frame to resiliently resist the rotation of the trailing arm toward the trailer frame, an axle mounted to the trailing arm, and a wheel mounted to the axle; the anti-creep device comprising: an arm adapted to be rotatably mounted to the trailer frame for movement between a retracted position and an extended position wherein, in the retracted position, the arm is disposed away from the suspension so that the axle is free to move up and down through a normal range of motion under ordinary conditions, and in the extended position, an end of the arm abuts a portion of the suspension to restrict the downward movement of the trailer frame with respect to the axle to prevent creep of the trailer frame away from a loading dock when loaded, at least when the end of the arm abuts the portion of the suspension.

2. An anti-creep device according to claim 1 and further comprising an actuator adapted to be mounted to the trailer frame and to the arm to control the movement of the arm between the retracted and extended positions.

3. An anti-creep device according to claim 2 wherein the actuator is an air-operated brake actuator adapted to be mounted to the trailer frame and having a shaft adapted to mount to the arm whereby the reciprocating movement of the shaft moves the arm between the retracted and extended positions.

4. An anti-creep device according to claim 1 wherein the portion of the suspension is the trailing arm.

5. An anti-creep device according to claim 4 wherein the arm is U-shaped with two opposing side members connected by a base member, the side and base members define a channel in which a portion of the trailer frame is adapted to be received, and the base member is adapted to abut the trailing arm when the arm is in the extended position.

6. An anti-creep device according to claim 5 wherein an elastomeric pad is mounted to the base member so that the elastomeric pad is adapted to abut the trailing arm when the arm is in the extended position.

7. An anti-creep device according to claim 5 and further comprising an actuator adapted to be mounted between the trailer frame and at least one of the side members to move the U-shaped arm between the retracted position and the extended position.

8. An anti-creep device according to claim 7 wherein the actuator is an air-operated brake actuator adapted to be mounted to the frame and having a reciprocating shaft mounted to at least one of the side members.

9. An anti-creep device according to claim 4 wherein the arm comprises a first plate adapted to be fixedly mounted to the trailer frame and a second plate rotatably mounted to the first plate, whereby the second plate is rotatable about the hinge between the retracted position and the extended position.

10. An anti-creep device according to claim 9 and further comprising an actuator adapted to be mounted between the trailer frame and the second plate to move the second plate between the retracted position and the extended position.

11. An anti-creep device according to claim 10 wherein the actuator is an air cylinder comprising a tubular portion adapted to be rotatably mounted to the trailer frame and a shaft reciprocally movable into the tubular portion and rotatably mounted at a distal end to the second plate, whereby as the shaft reciprocates with respect to the tubular portion, the second plate is moved between the retracted position and extended position.

12. An anti-creep device according to claim 4 wherein the arm has a hook which is adapted to abut the trailing arm when the arm is in the extended position.

13. An anti-creep device according to claim 12 and further comprising a stop bracket adapted to be mounted to the trailing arm and the stop bracket defines a chamber in which the hook is received when the arm is in the extended position.

14. An anti-creep device according to claim 13 and further comprising an actuator adapted to be mounted between the trailer frame and at least one of the side members to move the J-shaped arm between the retracted position and the extended position.

15. An anti-creep device according to claim 14 wherein the actuator is an air-operated brake actuator adapted to be mounted to the frame and having a reciprocating shaft mounted to at least one of the side members.

16. An anti-creep device according to claim 1 wherein the portion of the suspension is the axle.

17. An anti-creep device according to claim 16 wherein the arm is an elongated plate having one end adapted to be pivotally mounted to the trailer frame and having another end with a recess in which the axle is received when the elongated plate is in the extended position to prevent the upward movement of the axle.

18. An anti-creep device according to claim 17 wherein the trailer frame further comprises a cross-member and the elongated plate is adapted to be rotatably mounted to the cross-member.

19. An anti-creep device according to claim 17 and further comprising an actuator adapted to be mounted between the trailer frame and the elongated plate to move the elongated plate between the retracted position and the extended position.

20. An anti-creep device according to claim 19 wherein the actuator is an emergency brake actuator which is adapted to be mounted to the frame and having a reciprocating shaft mounted to at least one of the side members.

21. In a trailer having a trailing arm suspension, the trailing arm suspension comprising: a trailing arm rotatably mounted at one end to a trailer frame, an air spring mounted between another end of the trailing arm and the trailer frame to resiliently resist the rotation of the trailing arm toward the frame, an axle mounted to the trailing arm; and a wheel mounted to the axle; an arm rotatably mounted to the trailer frame above the suspension for movement between a retracted position and an extended position, in the retracted position, the arm is disposed above the suspension so that the axle is free to move up and down through a normal range of motion under ordinary conditions, and in the extended position, an end of the arm abuts a portion of the suspension to restrict the downward movement of the frame with respect to the axle to prevent creep of the trailer frame away from a loading dock when loaded, at least when the end of the arm abuts the portion of the suspension. -15-

22. A trailer according to claim 21 and further comprising an actuator mounted to the trailer and connected to the arm to control the movement of the arm between the retracted and extended positions.

23. A trailer according to claim 22 wherein the actuator is an air-operated actuator which maintains the arm in the retracted position when the air pressure is applied to the actuator and which moves the arm to the extended position when air pressure is exhausted in the actuator.