This invention pertains to mechanisms for lifting and manipulating heavy loads in general, and more particularly, to a loader for the main landing gear of a large aircraft.
Modern large aircraft, such as the Boeing 777, are typically assembled on a moving assembly line, sometimes referred to simply as a “Boeing Production System. (BPS)” Moving line assembly requires that the aircraft's main landing gear (MLG), each of which may weigh more 14,000 lbs., be installed while the weight of the aircraft is supported on jacks, with the belly of its fuselage disposed 106 inches or more above the floor. Moreover, repairs or maintenance of large aircraft in the field often must be effected in an actual “flight line” environment, necessitating the removal and installation of large MLG at heights of up to 154 inches above the tarmac, and additionally, in a potentially more hazardous environment, e.g., an Underwriters Laboratories (“UL”) “Class 1, Division 1” (fueled aircraft) environment.
The prior art methods for installing large MLG are typically accomplished on the flight line or in a customer's hangar. Several examples of specialized apparatus adapted for effecting such heavy equipment lifts and manipulations can be found in the patent art, e.g., in U.S. Pat. No. 5,460,474 to L. E. Iles; U.S. Pat. No. 6,390,762 to W J. Peery et al.; and, U.S. Pat. No. 6,485,247 to O. J. Groves et al.
One such prior art method and associated apparatus are those developed for loading the MLG of the Boeing 747 aircraft. However, it should be noted that the 747 MLG loader is not capable of supporting the increased weight of more recent, larger aircraft, e.g., the Boeing 777, and is therefore incapable of installing the 777 MLG in either a moving line or a flight line environment. This prior art MLG loader comprises three separate towers having associated floor plates that are installed concentrically to the MLG. The equipment necessitates that all six MLG wheels be removed from their respective axels, and that at least three protective sleeves be installed on the bare axels, two on the outboard side and one at the opposite inboard side on the center axle. The protective sleeves are in turn attached to three, six-ton lever hoists located on respective ones of the three towers. The lever chain hoists are attached to the plates and respective hoist chains are attached between the tower and the MLG, each of which are then independently tensioned or relaxed in the desired direction to align the upper end of the strut of the MLG into position inside the wheel well of the aircraft.
The foregoing sequence must be accomplished prior to either the installation or the removal of a MLG from an aircraft, and either case, the aircraft must first be fully supported on jacks or other supports. The disadvantage of the prior art method and apparatus is that they take substantial setup time and manual labor, including disassembly of the MLG wheels and the manual manipulation of the MLG with multiple, independent lever chain hoists, and with the subsequent need to reassemble three of the six wheels on the gear and disassemble the equipment after the MLG has been installed.
Accordingly, there is a long-felt but as yet unsatisfied need in the industry for a loader that can install a large MLG into or remove it from an aircraft in either a moving line or a flight line environment in a controllable, safe, accurate, reliable manner, and in a substantially reduced amount of time.
In accordance with the exemplary embodiments thereof described herein, the present invention provides a method and apparatus for loading the MLG of a large aircraft into or from the wheel wells of the aircraft in either a moving assembly line or a flight line environment in a safer, more reliable and accurate manner, and in a substantially reduced amount of time than those of the prior art.
In one advantageous exemplary embodiment, the MLG loader comprises a U-shaped support frame having opposing symmetrical portions disposed on opposite sides of a sagittal plane extending through the MLG, and a fixture supported on the support frame and coupled to the MLG such that both axial forces and turning moments applied to the fixture by the loader are coupled through the fixture to the MLG. The fixture may comprise, for example, an MLG shipping fixture that is coupled to the tires of the wheels on the MLG truck. Means are provided for both controllably translating and rotating the fixture in both a horizontal plane and the sagittal plane of the MLG.
The means for controllably translating the fixture in the sagittal plane include a pair of opposing slide mechanisms respectively coupled to an opposite side of the fixture and supported on a corresponding one of the opposing support frame side portions for simultaneous, coextensive sliding movement relative to the support frame and parallel to the sagittal plane, and means are provided, e.g., a ball-screw or hydraulic linear actuator, for urging the slide mechanisms in such movement.
The means for controllably rotating the fixture in the sagittal plane include first and second pairs of opposing vertical jacks, each pair having a jack supported on a corresponding one of the opposing support frame side portions, the first pair being fixed relative to the support frame and the second pair being axially moveable on the support frame relative to the first pair. Means are provided for rotatably coupling opposite ends of each of the slide mechanisms to an output end of a corresponding one of the jacks of each of the first and second pairs of jacks, and means are provided for controllably raising and lowering the output ends of the jacks of each opposing pair of jacks simultaneously, coextensively and independently of those of the other pair, such that the slide mechanisms, and hence, the fixture and MLG, are caused to rotate in the sagittal plane as a result thereof. The raising and lowering means of the jacks can also comprise a ball-screw or a hydraulic linear actuator.
In a preferred embodiment of the loader, means are also provided for controllably rotating and translating the fixture in a horizontal plane. These means can comprise a drive mechanism coupled to the support frame, in which the drive mechanism includes a plurality of synchronized, steerable wheels, each equipped with an independently controllable servo drive mechanism. In the preferred embodiment, all operations of the loader, including movement of the MLG in both the horizontal and sagittal planes, can be controlled by an operator remotely from the MLG using, e.g., a control pendant.
Optionally, the loader can include an electromechanical or a hydraulic linear actuator coupled between the strut and truck of the MLG which is operative to rotate the strut about a central axis of the strut and relative to the truck, for fine adjustments of the upper end of the strut relative to associated structure located in the wheel well of the aircraft.
In one advantageous embodiment, the loader can include a portable power supply, e.g., one or more battery or generator carts coupled to the loader, for powering the loader independently of fixed power sources.
A method for loading a MLG of an aircraft using the novel loader comprises coupling the fixture to the MLG and positioning the opposing side portions of the support frame on opposite sides of the fixture. The side portions of the support frame are then brought together and locked to each other such that the slide mechanisms of the loader respectively engage opposite sides of the MLG coupling fixture. When the MLG has thus been captured by the loader, the MLG can be easily translated and rotated in the horizontal plane using the loader drive mechanism so as to align it appropriately with the wheel well of the aircraft, then controllably translated and rotated in the sagittal plane of the MLG using the jacks and slider mechanisms until the upper end of the strut of the MLG enters the wheel well and is correctly aligned with associated engaging structure located in the wheel well.
A better understanding of the above and many other features and advantages of the methods and apparatus of the present invention may be obtained from a consideration of the detailed description of the exemplary embodiments thereof below, particularly if such consideration is made in conjunction with the appended drawings, wherein like reference numerals are used to identify like elements illustrated in one or more of the figures therein.
In
An advantageous tool 50 for grasping and holding the MLG 16 for such manipulation by a loader is illustrated in the perspective view of
An exemplary embodiment of a MLG loader 60 in accordance with the present invention is illustrated in the perspective view of
As illustrated in
As illustrated in, e.g., the top plan view of
Each foot-block assembly 78 is positionable on a horizontal rail of a respective one of the slide mechanisms 76 by means of a 10-ton ball-screw linear actuator 80 driven by a one-horsepower electric motor equipped with a C-face braking mechanism. The electric motor is connected to an inline gear box having a 5:1 gear ratio mounted to a bracket and coupled to the ball-screw actuator. The actuator ball screw nut is attached to the foot-block assembly by means of a bracket. A first, or forward one, of the two foot-block assemblies of each bilateral slide mechanism is adjusted by positioning it manually on the rails of the slide mechanism to align with the MLG coupling fixture 50 described above when the loader 60 is initially coupled to the MLG 16, whereas, the aft one of the foot-blocks of each slide mechanism is allowed to float freely on the rail of the slide mechanism. The forward foot/block assembly is then positioned and controlled by the electric drive motor of the linear actuator. Thus, when the motor drives the primary foot-block of a respective slide mechanism, it simultaneously controls translational movement of both of the aft foot-blocks and the fixture, and hence, the translational movement of the MLG in the sagittal plane. The respective slide mechanisms 78 of the two L-shaped half-units 62L and 62R thus translate simultaneously and coextensively with each other to translate the MLG 16 in the sagittal plane relative to the U-shaped support frame 66, regardless of the rotational position of Θy of the MLG in the sagittal plane, which is controlled by the loader in the following manner.
In the exemplary embodiment of the loader 60 illustrated, each of the two pairs of opposing vertical jacks 68, 70 comprises a one-horsepower electric motor with a C-face brake that attaches to an in-line helical box having a 5:1 gear ratio. The gear box attaches to a miter gear box having a 1:1 gear ratio, which in turn, attaches to a 20 ton ball-screw mechanism 82. The screw nut of the ball-screw mechanism is restrained from rotating by fixing it, e.g., by means of a weldment on a respective slide mechanism 76, and is attached to a respective one of the two block feet 78 of a respective slide mechanism. In one exemplary embodiment, the maximum stroke or extension of the jack ball screw mechanisms, and hence, the output ends 72, 74 of the jacks, is adjusted to be about 65 inches. However, the stroke can be extended for use of the loader in, e.g., a flight line environment in which a greater stroke may be required.
The vertical position of the MLG 16, as well as its rotational position Θy in the sagittal plane and relative to the support frame 66, is thus controlled by the vertical stroke of the four jacks 68, 70 acting in concert, in the case of the vertical position of the MLG 16, or in concerted, opposing pairs, i.e., the front, or forward opposing pair 70L and 70R moving in concert with each other, and/or the aft, or rearward pair 68L and 68R moving in concert with each other and independently of the front pair. Thus, if the MLG is loaded onto the loader 60 with the strut end 20 extending forward relative to the loader, as illustrated in the front-and-left side perspective view of
In a preferred embodiment, the loader 60 is driven over the ground by a drive mechanism comprising six, synchronized, steerable, nine-inch dual-wheel assemblies 86, each equipped with an electric servo drive. The drive mechanism enables an operator of the loader to precisely control the x and y positions of the loader, and hence, the MLG, relative to the wheel well 22 of the aircraft 10 from outside of the aircraft using, e.g., a control console located on the loader, or a control “pendant,” i.e., a control pad attached to the loader by an electric cord (preferably, one which is UL rated for Class 1, Division 2, i.e., a flight line environment), or alternatively, by a wireless RF connection. As those of skill in the art will appreciate, the drive mechanism also provides the loader with an additional degree of rotational control, namely, the ability to rotate in the horizontal plane (“Θz”), i.e., about the vertical z axis. The total weight of the MLG Loader is distributed over the wheels of the drive mechanism such that the bearing weight of the fully burdened loader does not exceed a rated floor load of 450 PSI. In the exemplary embodiment of the loader 60 illustrated in the figures, the total weight of the loader is about 26,000 lbs., and its overall dimensions are 190 inches long×194 inches wide×120 inches high.
In one advantageous embodiment, the MLG loader 60 is provided with a pair of battery carts 88 (see
The method used for attaching the exemplary loader 60 of the present invention to the MLG 16, and thence, the MLG to the aircraft 10, is as follows. The MLG is initially provided at the location of the loader, e.g., with a forklift, with the shipping fixture 50 already coupled to the wheels 26 of the MLG truck 24. The two L-shaped half-units 62L and 62R of the loader are then moved toward each other across the sagittal plane of the MLG until opposing fingers on respective ones of the slider assemblies 76L and 76R engage in respective openings on opposite sides of the fixture. The two L-shaped units are then locked together such that the slider mechanisms, together with the fixture, define a single platform coupled to the MLG that can be raised, lowered, horizontally traversed, and rotated about two axes of rotation, through control of the loader.
The operator of the loader 60, while positioned, for example aboard the loader on one of the work platforms 84 thereof, or remotely from the loader, can then steer the loader and MLG into position under the wing of the aircraft 10 at the position of the desired well 22, and using the control pendant, manipulate the MLG up into the wheel well without causing any interference between the MLG and the airplane wing or any auxiliary working or support stands that provide access and/or support of the airplane on the moving assembly line.
By now, those of skill in this art will appreciate that many modifications, substitutions and variations can be made in and to the materials, apparatus, configurations and methods of MLG loader of the present invention without departing from its spirit and scope. For example, in an appropriate situation, hydraulic linear actuators can be substituted for one or more of the electrical ball-screw linear actuators illustrated and described herein. Accordingly, the scope of the present invention should not be limited to that of the particular embodiments illustrated and described herein, as they are only exemplary in nature, but rather, should be fully commensurate with that of the claims appended hereafter and their functional equivalents.