Spring devices – Vehicle – Comprising compressible fluid
Reexamination Certificate
2002-03-27
2003-11-18
Schwartz, Christopher P. (Department: 3683)
Spring devices
Vehicle
Comprising compressible fluid
C267S182000, C060S453000, C092S079000, C254S132000
Reexamination Certificate
active
06648311
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an assembly for exercising a hydraulic strut of an aircraft.
As part of regular maintenance of an aircraft, the struts of the aircraft carriage are inspected and serviced. These struts are typically hydraulic and require periodic recharging of the hydraulic fluid that provides the damping between the piston and the cylinder of the strut.
Recharging involves replacing the lost hydraulic fluid by pumping hydraulic fluid through an opening of the strut's cylinder. During this process, however, air is unintentionally introduced into the cylinder, creating air pockets within the hydraulic fluid of the strut. These air pockets may affect the strut's performance. Accordingly, it is desirable to remove air from the hydraulic cylinder.
One technique employed for removing air from the cylinder involves the placement of a tire jack underneath the tires of the aircraft strut. The jack is pumped up and down causing the cylinder of the strut to be exercised, i.e., telescoped in and out relative to the piston of the strut. The relative movement of the piston to the hydraulic cylinder causes air to be worked out of the cylinder.
This technique is cumbersome. The round tires of the strut may bounce or slip off the platform of the jack even if the wheels are secured against rotation. Moreover, the technique is labor intensive, requiring a technician to manually pump a jack.
A need therefore exists for a method and assembly that permits excess air to be worked out of the hydraulic cylinder in an efficient manner.
SUMMARY OF THE INVENTION
The present invention comprises an assembly and technique for introducing hydraulic fluid and removing excess air from a strut of an aircraft. The assembly includes a couple that is selectively connectable to the strut. The couple secures the strut to a driver that moves the strut up and down, thereby exercising excess air from the strut.
The strut exercise assembly may include a source of hydraulic fluid that provides fluid to the strut. In this way, the strut may be filled with fluid while the driver exercises the strut. The couple ensures that the strut will remain closely connected to the driver and prevent the strut from disconnecting from the driver while in motion.
The assembly may also include a frame to support the fluid strut. A lever may be made part of the assembly to support the couple while the strut is in the frame. The lever may help distance the driver from the strut, creating a safer work environment and adding leverage to the action of the driver. The driver may be pneumatically powered rather than manually powered. It may further drive the strut in an oscillating fashion. A control switch may actuate operation of the driver.
The couple may have a feature that mates with a feature of the fluid strut, securing the connection between driver and strut. For example, the couple may be a peg that fits into a hole of the strut. Also, the couple may have a cup that embraces a rounded end of the strut.
By using this assembly, an aircraft strut may be coupled to a driver. The strut may be then filled with fluid, and the strut exercised by the driver by telescoping the strut up and down. Air may be bled from the strut while the fluid is exercised.
Thus, the present invention provides the benefits of exercising the strut through a driver that is coupled securely to the strut. A technician may exercise the aircraft strut without the exertion of significant manual effort. In addition, he may do so without concern about the strut.
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Carlson & Gaskey & Olds
Kramer Devon
Pentastar Aviation, Inc.
Schwartz Christopher P.
LandOfFree
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