Patent Application
20060119089
1. Field of the Invention
The present invention relates to a stabilizing leg apparatus for a trailer, and more particularly to a stabilizing leg apparatus that can be mounted aft of the trailer wheel assembly or in close proximity to the front end of the trailer.
2. Description of the Prior Art
Many semi-trailers have landing gear for support of the front of the trailer when the tractor is detached. Such landing gears generally have two spaced-apart, jack-type structures joined by a cross-driven shaft engaged to a gear reduction box assembly. The gear reduction box assembly, which typically has two gearing ratios—a low gear and a high gear, may be driven by a manually operated crank. The high gear ratio is for quickly lowering the landing gear to the ground and the low gear ratio is for lifting and supporting the front end of the trailer on the landing gears.
Many devices for the motorized extension and retraction of front landing gear apparatuses for semi-trailers are known. Typical of such devices is U.S. Pat. No. 4,466,637 to Nelson, which discloses an electric motor to drive the usually manually operated crank system for raising and lowering of the semi-trailer landing gear. Pneumatically powered actuators for raising and lowering the semi-trailer's landing gear are disclosed in U.S. Pat. Nos. 4,400,986 and 4,402,526. These patents disclose a complex structure to receive pressurized air for the actuators to rotate the crank shaft of the gear reduction assembly to raise and lower the front landing gear. U.S. Pat. No. 4,345,779 to Busby discloses a pneumatically operated drive unit attached to the shaft of the gear reduction box assembly for raising or lowering a front landing gear. The drive unit uses a pneumatic impact motor. U.S. Pat. No. 3,503,588 to Bach discloses hydraulic pistons for raising and lowering front landing gear. The hydraulic system of Bach is large and cumbersome, and hydraulic pistons do not provide the same positive holding as provided by a gearing arrangement. Power failure or loss of pressure could cause failure and collapse of the landing gear.
U.S. Pat. No. 5,299,829 to Rivers, Jr. et al., which is incorporated herein by reference, discloses an improved front landing gear raising and lowering system using a vane-type pneumatic motor utilizing air from the vehicle's existing air pressure lines that extend to the brakes of the trailer. The invention disclosed in this patent solved many of the prior art shortcomings with respect to the automatic operation of front landing gear on trailers.
Typically the trailer portion of a tractor-trailer rig is uncoupled from the tractor portion during loading and unloading. The trailer is parked adjacent to a loading dock and the contents of the trailer are loaded and unloaded using a tow motor or a conveyor belt mechanism, for example. The heavy weight of the tow motor, the movement of the contents, and/or the uneven removal of the load within the trailer can negatively affect the stability of the trailer. Moreover, in trailers fitted with air-suspended axles, settling of the rear of the trailer, due to loss of air pressure in the suspension or heavy loads being placed in the rear of the trailer, could cause shifting or tilting of the trailer, including misalignment of the front end of the trailer with the loading dock. Thus, in those instances when only the forward part of the trailer is supported by landing gear, the trailer could shift or tilt, possibly becoming unstable.
In addition, most of the landing gear arrangements currently available for supporting the forward portion of the trailer are positioned some distance behind the forward edge of the trailer, and a distance inward from each side of the trailer. As a result, even the front portion of the trailer is not completely stable.
What is needed is an apparatus that increases the stability of the trailer when loading and unloading the trailers and that is easy to operate. Thus, there exists a need for support apparatus that can be located aft of the wheel assembly of the trailer and adjacent the forward edge of the trailer.
A stabilizing leg apparatus for stabilizing a trailer during the loading or unloading of goods transported by the trailer is provided. The trailer includes a transport container and a wheel assembly coupled to the transport container. The transport container has a front end, a rear end, a first side, a second side, and an underside. The container has a width that extends between the first side and second side, and between the rear end and the front end. The wheel assembly is located between a midpoint of the transport container and the rear end of the transport container. The stabilizing leg apparatus includes at least one stabilizing leg. The stabilizing leg apparatus is selectively operable between a transport position wherein the stabilizing leg does not contact ground and a stabilizing position wherein the stabilizing leg does contact ground. In one embodiment, the stabilizing leg apparatus mounts adjacent each side of the container aft of the wheel assembly, adjacent the rear end of the trailer.
In another embodiment, the stabilizing leg apparatus mounts on the transport container adjacent the rear end, approximately midway across the width of the transport container.
In still another embodiment, the stabilizing leg apparatus mounts forward of the trailer's landing gear, adjacent the front end of the trailer.
The present invention includes a trailer for transporting goods that has one or more of the stabilizing leg apparatus embodiments described herein.
Referring to
The stabilizing leg apparatus 10 includes at least one stabilizing leg 20, which is mounted on the transport container 22.
In some embodiments, a stabilizing leg apparatus 10 is mounted on the transport container 22 aft of the wheel assembly 19. In other embodiments, a stabilizing leg apparatus 10 is mounted forwards of the trailer landing gear 12, adjacent the front end 21 of the trailer 100. Examples of a stabilizing leg apparatus 10 that is operable to change between a transport position and a stabilizing position include, but are not limited to, one that is retractable within itself, one that is mounted so as to be retractable within the container 22, and one that is mounted so as to be rotatable away from the ground (e.g., pivotable about an axis 13; see
Referring to
Each leg 24, 26 includes an inner member 30, an outer member 32, and a base 34. Inner member 30 is telescopically received within outer member 32. Base 34 (e.g., a foot) is connected to the lower end of inner member 30. In operation, inner member 30 may be actuated from within outer member 32. As mentioned above, actuation of first and second legs 24, 26 can be coordinated via connecting shaft 28. The details of the vertical support structure for tractor-trailer landing gear are well known to those skilled in the art and may be applied to the details of the vertical support structure of legs 24, 26. As such, these details are not discussed further herein.
Referring to
Motor 16 is mounted on second side 44 of outer member 32 of drive leg 24. Motor 16 is attached to a bracket 82 secured to outer member 32. Shaft 80 of the motor (“motor shaft”) is connected to drive mechanism 14. Drive mechanism 14 also includes gear assembly 46, which includes a drive gear 60. Drive gear 60 is mounted on an internal shaft 52. In the embodiment shown in
As shown in
Drive gear 60 is engaged with spur portion 70 of output gear 56. During power-assist operation, the engagement between drive gear 60 and output gear 56 drives bevel gear 36 and threaded shaft 38 in drive leg 24, thereby extending or retracting drive leg 24. Rotation of output gear 56 also causes rotation of output shaft 50. In the power-assist mode, manual input shaft 48 is non-operational, or in other words, manual input shaft 48 is bypassed.
For manual operation, gear assembly 46 also includes a manual input gear 54 and an intermediate gear 58 mounted on internal shaft 52. Internal shaft 52, shown mounted in outer member 32, extends substantially parallel to manual input shaft 48 and output shaft 50. Output shaft 50 and manual input shaft 48 are mounted within outer member 32 and are axially aligned with one another. Input shaft 48 has a first end 62 and a second end 64. First end 62 of input shaft 48 is adapted to receive a hand crank 65 on first side 42 of outer member 32. Second end 64 of input shaft 48 extends through an opening in first side 42 of outer member 32 and into the interior of outer member 32.
Output shaft 50 also has a first end 66 and a second end 68. Second end 68 of output shaft 50 may be operatively connected to connecting shaft 28 on second side 44 of outer member 32. As shown in
Manual input shaft 48 is adapted for axial movement within outer member 32 between a first position (
When manual input shaft 48 is in the first position (
As discussed above, connecting shaft 28 operatively connects output shaft 50 of drive leg 24 to an input shaft of slave leg 26. Slave leg 26 preferably has an extension mechanism that does not require any intermediate shaft or shifting mechanism. For example, the second leg could utilize an input shaft/output gear subassembly and a bevel gear/threaded shaft subassembly similar to those described above to move inner and outer members 30, 32 between retracted and extended positions.
In alternative embodiments, other gear arrangements (e.g., a rack and pinion gear set, a worm gear arrangement, etc.) could be incorporated into drive mechanism 14 to convert rotation of a motor shaft 80 into linear motion so that inner and outer members 30, 32 can be driven between a retracted position and an extended position as will be discussed below.
Motor 16 may be electrical, hydraulic, pneumatic or any other known motor. Indeed, motor 16 could also be an internal combustion engine. However, referring to
A variety of air sources 84 can be used to supply pneumatic motor 15. For example, a compressed air storage cylinder could be attached to trailer 100 or transport container 22, or a local source of compressed air, for instance, a source of compressed air at a loading/unloading dock, can be used. Preferably, air source 84 is portable and travels with the tractor-trailer so that it is readily available to operate the support leg apparatus. In a preferred embodiment, compressed air source 84 is the existing air supply from an emergency brake system of the tractor-trailer.
Referring to
In a preferred embodiment, controller 18 includes a valve 94. Valve 94 acts as an air shutoff valve that controls the direction and amount of air pneumatic motor 15 receives. In some embodiments, valve 94 will only provide an airflow to pneumatic motor 15 if valve 94 is manually opened and retained in the open position (e.g., by manually moving a spring-biased lever 96 as shown in
Valve 94 is also preferably a three-position valve that includes an “neutral” position, a first supply position (“down”), and a second supply position (“up”). As noted above, valve 94 is biased to the “neutral” position. Lever 96 enables the operator to move valve 94 between the “neutral” position and either of the first or second supply positions. Valve 94 is connected to pneumatic motor 15 such that air passing through valve 94 when in the first supply position causes pneumatic motor 15 to rotate in a first direction (e.g., clockwise) associated with downwardly extending stabilizing legs 24, 26 (see
In alternative embodiments, valve 94 can be a power-assisted type control valve that utilizes one or more solenoids, for example to actuate valve 94 to the first or second positions. Such a power-assisted valve 94 may be configured so that the user operates valve 94 in proximity of valve 94 or at a position remote from valve 94 (e.g., from the cab of the tractor-trailer). Even with such alternative valve designs, however, valve 94 is preferably biased towards the “neutral” position. Pneumatic control valves are known in the art and the operation thereof need not be discussed further herein.
In one embodiment, a lubrication unit 98 (e.g., an automatic oil mist lubricator) is provided upstream of pneumatic motor 15, and more preferably upstream of both motor 15 and valve 94. Lubricator 98 treats the air with a fine oil mist so that valve 94 and motor 15 are lubricated and so that they can operate efficiently. Automatic lubrication units 98 are known in the art and will not, therefore, be further described herein.
As discussed above, stabilizing leg apparatus 10 may be operated in a power-assist mode and in a manual mode. Thus, in one embodiment, an operator could operate a hand crank 65 attachable to a manual input shaft 48 mounted on the drive leg, as shown in
When it is desired to manually operate stabilizing legs 24, 26 in the low gear, input shaft 48 is axially moved to a first axial position (
In those embodiments where the stabilizing leg apparatus 10 includes two stabilizing legs, both legs 20 may be drive legs 24. In this configuration, each leg 24 has its own motor 16 and drive mechanism 14 (within outer member 32), and thus, each leg 24 may be retracted or extended independently of the other. This embodiment may be preferred, for instance, if stability requirements specified individual stabilizing units on each side or if there existed an obstruction underneath trailer 100 that prevented the use of connecting shaft 28.
To actuate the stabilizing leg apparatus 10 in the power-assist operation mode, the operator moves control valve 94 into the supply position designated “down” for extending stabilizing legs 24, 26. In the “down” position, the compressed air powers pneumatic motor 15, which in turn actuates drive mechanism 14. Bevel gear 36 and threaded shaft 38 rotate, thereby causing the respective inner members 30 to move relative to outer members 32 of both drive leg 24 and slave leg 26. Legs 24, 26 extend until bases 34 for each leg 24, 26 contact the ground. Once the desired position of bases 34 is reached, the operator releases valve lever 96 and valve 94 automatically returns to the “neutral” position. When the operator elects to retract stabilizing leg apparatus 10, valve 94 is moved into the supply position designated “up.” In the “up” position, the compressed air powers motor 15 and the attached drive mechanism 14 in the opposite rotational direction as assumed for the “down” direction. As a result, the movement of the bevel gears 36 and threaded shafts 38 of drive and slave legs 24, 26 are reversed and the respective inner members 30 are actuated upwardly within outer members 32 to bring bases 34 clear of the ground. Once a desired position of inner members 30 and bases 34 is reached, the operator releases valve lever 96 and valve 94 automatically returns to the “neutral” position. In those embodiments wherein the stabilizing leg apparatus 10 either retracts within the container 22, or is rotated away from the ground, once the legs 20 are no longer in contact with the ground, the operator is free to either retract the legs 20 further into the container 22 or rotate the legs 20 into a storage position.
If a compressed air source is not available, the present invention can be still used with hand crank 65 and manual input shaft 48, wherein stabilizing legs 24, 26 can be manually extended or retracted as desired in accordance with known practice. Such a capability is helpful in situations where the air source of the tractor-trailer must remain dedicated to the emergency brake line, or is not available.
Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the invention.
