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LOCATED IN THE HYDRAULIC CASTER VALVE BLOCK
ASSEMBLIES, SHOULD NOT BE REMOVED UNLESS ABSOLUTELY
NECESSARY. THE HYDRAULIC CASTER RELIEF VALVES ARE SET
TO BY-PASS HYDRAULIC FLUID BACK TO THE RESERVOIRS AT 900
± 20 psig (63.3 ± 1.4 kg/sq cm) IF ADJUSTMENT IS REQUIRED, SEE
PROCEDURE UNDER TESTING (SEE SHEET 5).
When necessary to disassemble the jack and/or the hydraulic casters (if so equipped), open all release
valves, drain all hydraulic fluid from reservoirs and carefully inspect the following:
1. Inspect interior walls of cylinders for smoothness and freedom from rust, nicks, scratches and
excessive wear.
2. Check plungers, extension screw, cylinders, tripod head, etc., for corrosion, wear and condition of
threads.
3. Verify that the extension screw has a positive stop to prevent it from being extended beyond its safe
thread engagement.
4. Inspect packings, seals, gaskets and wipers in the cylinder assembly, hand pumps and hydraulic
caster assemblies for cuts, scratches, deterioration and distortion.
5. Inspect upper and lower bearings for excessive scoring and/or wear.
6. Check oil screen located in the valve block for cleanliness.
7. Inspect valves and valve seats in the hand pump bodies and valve blocks for scratches, dents and
proper seating of the balls.
8. Inspect all pivot pins for wear, cracks, pits or evidence of damage or pending damage.
9. Check tripod structure for damages.
10. Inspect all areas for excessive dirt, oil, dust and chips.
REPAIR AND REPLACEMENT:
No definite time schedule can be established for the overhaul of the jack for replacement of the various
moving parts. The number of times the jack is raised and lowered and the amount of load raised at each
operation materially affect the life of the working parts. Do not overload the jack. Overloading is
dangerous, will hasten the need for overhaul and may damage the jack. During overhaul, replace all parts
that do not pass disassembly inspection requirements. Regardless of apparent condition, replace all parts
marked with (♦) and (✚) in the parts breakdown. A repair parts kit (P/N 795PK) which contains all of the
parts marked with (♦) and a hydraulic caster repair parts kit (P/N 8818PK) which contains all of the parts
marked with (✚) are available and recommended to keep on hand at your facility. Coat all O-rings and
back-up rings with hydraulic fluid MIL-H-5606 prior to assembly. Clean all metal parts with clean solvent
and dry with compressed air. Lubricate all threads. Use teflon tape carefully on all pipe threads. Remove
excess tape because it can clog valves and passages. If ball valves, located in valve blocks, do not seat
properly, they may need to be reseated by tapping the ball into the valve seat with a brass rod cupped at
one end.
TESTING:
Place jack in a load indicating test fixture. Make sure the test adapter is 1 1/4 inch female spherical
radius. Operate jack hand pump to extend plunger against the test adapter. Make sure ship adapter and
test adapter are correctly mated. Load test the jack at rated capacity of 100 tons. If the jack fails to
operate properly, check for trouble as indicated in the Trouble Shooting Chart (see sheet 12). With the
plunger extended and supporting the capacity load, allow the jack to stand for 10 minutes. Any excess
settling indicates leakage in the hand pump, check valves or jack packing seals. Check for hydraulic fluid
leaks and replace all defective parts.
If adjustment is required for the jack thermal relief valve, perform the following procedure:
1. Remove plug (figure 3, item 8) to expose thermal relief valve. Close release valve (figure 3, item 2).
2. Place jack in a load indicating test fixture. Make sure the test adapter is 1 1/4 inch female spherical
radius. Operate hand pump to extend plunger against the test adapter. Make sure ship adapter and
test adapter are correctly mated.
Property of American Airlines
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