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 TM 55-1905-220-14-10
5-21. HYDROSTARTER - MAINTENANCE INSTRUCTIONS (Continued).
LOCATION
ITEM
ACTION
REMARKS
TESTING (Cont)
f.
Open control valve slowly to full open position.
Hold open for 3 seconds before closing. While con-
trol valve is in open position, a pressure drop of
500 psi (3447.4 kPa) maximum is permissible.
g. Proceed to test each of the pistons in the manner
described above by rotating lock test tool in in-
crements as provided until all pistons have been
tested. Should pressure drop faster than speci-
fied when testing at one particular position, it
will of course indicate internal leakage. This
could be a piston which would require replacement.
NOTE
Turn lock test tool and shaft one full turn and retest before
replacing any one particular piston. A pressure drop at all
pistons indicates that port plate fastening screws (8) are not
properly torqued or that there is insufficient spring tension to
keep barrel (11) against port plate (6). It may be necessary to
lap port plate (6) and barrel (11) on a lapping plate or replace
spring (14) to eliminate leakage.
NOTE
Port plates are lapped at the factory with the straight fittings
installed in both ports. Fittings are torqued to 25 lb. ft. (33.9
Nm). Leave these fittings in the port plate when testing or
lapping. If they have been removed, replace with new fittings
when testing or lapping.
h. After the preceding test is complete, remove lock
testing tool.
5-392
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