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Hydraulic Actuator Project

Hydraulic Actuator Project. Development of Materials Joint Test Protocol has been work-in-progress for more than one year; large number of contributors and intermittent amount of time devoted to bringing it together

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Hydraulic Actuator Project

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  1. Hydraulic Actuator Project • Development of Materials Joint Test Protocol has been work-in-progress for more than one year; large number of contributors and intermittent amount of time devoted to bringing it together • In Summer 2001, decided to concentrate on developing and executing a rod/seal functional test to assess performance of HVOF coatings against selected seal materials • Initially expected contractor to perform work, but in Fall 2001 became aware of test apparatus at NAVAIR Pax River used for assessing new seal materials; assessment determined that this would be ideal for HCAT planned work

  2. NAVAIR Pax River Seal Testing Information provided by Jeff Moorman at Pax River • Problem was that large percentage of components on Navy aircraft hydraulic systems removed due to external leakage • Most components are packed with Nitrile rubber seals which is damaged above 200o F; amount of seal damage is cumulative with exposure time and increases rapidly with elevated temperatures • Pax River used in-house test apparatus to identify and qualify a seal material that would better withstand operating conditions by eliminating or delaying external leakage • Seal failure modes include hardening and cracking, abrasion, and extrusion

  3. Pax River Test Apparatus Environmental Chamber: Temperatures from -65 to +300 deg.F; hydraulic power supply is outside chamber Drive rod goes through chamber wall; hydraulic pressures inside seal fixture are varied between 1000 and 3000 psi

  4. Pax River Test Apparatus Test apparatus mounted in environmental chamber; consists of four rods with pair of seal blocks per rod Primary seals in blue, secondary seals in magenta; two seal configurations per block and 16 seal configurations under test

  5. Pax River Test Apparatus Schematic

  6. Pax River Test Spectrum to be Usedon Evaluation of HVOF Coatings Cycle Details - Each hour consisted of: 20 minutes sine wave 3.5 in pk to pk with period of 1.5 seconds.  Max velocity of 8 in/sec. 20 minutes sine wave 2.0 in pk to pk with period of 4 seconds superimposed with a dither 3/8 inch pk to pk at 4 Hz. 20 minutes sine wave dither in place 3/8 inch pk to pk at 4 Hz. Testing was performed in 16 hour days. First day at 300 degrees F with 25 degree drop on each subsequent day. Stand was cold soaked to 0 degrees F between testing blocks. Block 6 at 175 degrees F was followed by -40 degree F soak and 4 hours at 300 degrees F to complete 100 hours. Internal pressures were actuator drive pressures which varied from 500 to 2500 psi throughout testing.

  7. Test Matrix for Evaluation of HVOF Coatings

  8. Current Status • Test rods have been fabricated at Metcut and are being shipped to NRL • Working to finalize test document and get cost proposal from Pax River

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