Test System for Wheel Bearings

The present invention relates generally to a wheel bearing test system, in particular a wheel bearing test system for aircraft wheel bearings.

Many testing devices have been provided in order to test components prior to utilization in their intended environment. It is highly desirable to provide a testing apparatus that effects as realistic an environmental testing as possible. There is a need for an aircraft wheel bearing test system which will provide realistic duplication of the actual environment in which the wheel and bearings will operate. The bearing test system should provide an accurate means for evaluating aircraft wheel bearings while mounted in a simulated wheel and on a simulated axle both of which provide representative aircraft component stiffness, functions, and operational environment. The test system must be capable of producing loads comparable to those developed during actual aircraft operation sequences, i.e., ramp positioning, taxi maneuvers, takeoffs, drift landings, and so on.

The present invention comprises motor means connected with a fixed support, a wheel connected with the motor means, axle means upon which the wheel is mounted via wheel bearings, an axial load application mechanism disposed substantially coaxially with said axle means, a radial and moment load application mechanism, a connecting member connecting together the axial load application mechanism, radial and moment load application mechanism, and axle means, load sensing devices associated with the load mechanisms, and control means, so that activation of the respective load mechanisms effects the selective imposition of loads upon the bearings during rotation of the wheel by the motor means and when the wheel is at rest.

One way of carrying out the invention is described in detail below with reference to the drawings which illustrate a specific embodiment, in which:

FIG. 1 is a schematic representation of the wheel bearing test system of the present invention and

FIG. 1A is a schematic representation of the control mechanism of the present invention.

The wheel bearing test system of the present invention is indicated generally by reference numeral 10 in FIG. 1. System 10 comprises a motor 12 including a shaft 14, the motor 12 attached to a fixed support 15. The motor shaft is surrounded by load reaction bearings 16. Attached to the motor-driven shaft 14 is a wheel attachment fixture 18 shaped to receive the outer radial flange portions of an aircraft wheel 20. Aircraft wheel 20 may have the outer radial flanges removed in order to simplify its attachment by bolts 22 to the support structure 18. The wheel is mounted upon mandrel assembly or axial means 30. The mandrel assembly or axle means 30 has positioned thereabout test bearings 40, which typically comprise roller bearings utilized in aircraft wheel assemblies, or other bearings depending on the type of wheel and bearings to be tested. The axle means 30 is nonrotably attached along area 36 to a T-shaped connecting member 50. T-shaped connecting member 50 comprises legs 52, 54, and 56. Disposed substantially coaxially with axle means 30 is an axial load application mechanism 60. Mechanism 60 is pivotally attached at 65 to fixed member 15 and includes a cylinder rod 62 pivotally attached at 64 to leg 52 of T-shaped connecting member 50. The axial load application mechanism comprises an axial hydraulic load cylinder that is aligned substantially linearly with the axle means. Located substantially orthogonally relative to axle means 30 is a pair of radial and moment load application mechanisms indicated generally by reference numeral 70. Mechanism 70 comprises a pair of hydraulic radial and moment load cylinders 72 and 74, each pivotally attached at 75, 77, respectively, to fixed support 15. The pivotal attachments at 65, 75, and 77 allow multi-planar movement of connecting member 50, and thus the axle means 30 is multi-planar movable by means of the multi-planar movable connecting member 50 to which the axle means is fixedly connected. At the other end, cylinders 72 and 74 have rods 78 and 79 attached pivotally at pivot points 84 and 86 on respective legs 54 and 56 of T-shaped connecting mechanism 50. Each load cylinder 60, 72, and 74 includes therewith load sensing devices 61, 73, and 76, respectively, which enable the loading forces effected by the respective hydraulic cylinders to be sensed and communicated to a control mechanism 100. The control mechanism 100 receives the sensed loads and ensures that the appropriate forces are effected by the respective cylinders in order to effect the desired loading forces which are inputted to the controller. Additionally, strain gauges and rotary encoders may be placed on each cylinder rod to detect bending of the rods. The strain gauges and rotary encoders can communicate with the control mechanism 100 (typically a computer) so that the control mechanism compensates for bending and accurate results are obtained.

The wheel bearing test system of the present invention enables a highly accurate and realistic testing of wheel bearings while in their intended environment. At the start of each test sequence, all load sensing devices are electronically zeroed to a reference point wherein they are representative of an unloaded position. The controller receives, via the load sensing devices, the applied loads, and may record temperature variations. A load sensing device 31 on the mandrel 30 provides verification of the composite-applied loads magnitude. Motor 12 effects rotation of wheel 20 while mechanisms 60 and 70 are actuated selectively to provide a singularly or in combination: axial loading, radial loading, and moment loading applied via the axle means 30. Hydraulic cylinders 72 and 74 may be actuated selectively so that a net radial load is applied to the wheel bearings, or so that a combination radial load and moment load is applied to the wheel bearings. By controlling selectively the operation of the motor via the controller, various operational sequences may be run in order to duplicate the environment in which the wheel bearings operate during ground turns, drift landings, a five-point brake roll, maneuvering at low speeds, takeoffs, and landings. It has been found that the most severe wear experienced by wheel bearings is during maneuvering and takeoff operations. Thus, the environment of these operations can be successfully duplicated and repeated any selected number of times in order to test the capability of the wheel bearings. It is possible to impose infinite load variations upon the wheel bearings because of the orientation and number of load cylinders. Also, the loading effected upon wheel bearings by stationary aircraft can be effected simply by actuating the appropriate load cylinders.

While the invention has been described with respect to the detailed embodiment, it will be understood that the invention is capable of numerous rearrangements, modifications, and alterations, and such are intended to be within the scope of the appended claims. It is reasonably to be expected that those skilled in the art can make numerous revisions and additions to the invention and it is intended that such revisions and additions will be included in the scope of the following claims as equivalents of the invention.