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 TM 55-1905-217-12
(3) With selector valve in normal position (IN).
(9) Reassemble elements ,by installing the
Loosen connection tat each ramp locking cylinder,
outer element over the inner element, snapping it into the
retighten when fluid is free of bubbles.
flat end cap of the inner element and pressing together.
(4) Disengage engine driven pump and place
(10) Place conical shaped end member of the
sector valve in EMERGENCY position (OUT). Pump
element into the housing and carefully push the entire
hand pump to build up pressure.
filter assembly into the housing. Rotate element slightly
(5) Loosen connection at selector valve from
to 'be sure the conical shaped seal surface of the outer
hand pump, retighten when fluid is free of air bubbles.
element is properly seated.
(6) 'Return all controls to normal or neutral
(11) Install the cover seal, 'being careful that the
position.
ring is in the correct position and is not twisted. Be sure
the element spring is securely fixed to spring retainer in
the center of the cover. Push the cover into place, being
4-87. Ramp Hoist System Filters and Strainers
sure the end member of the element is in its pocket.
a. Filters (Return Line). Observe the filter condition
Install bolts.
indicator (fig. 2-9) daily when the system is in operation.
c. Suction Screen Service, Hull Numbers 8520 thru
Filter elements must be changed when the needle moves
8560 and 8580 thru 8618.
into the red danger zone. Change the elements only
(1) These screens are located in the 75gallon
when the ramp hoist pumps are not in operation.
ramp hoist hydraulic system tank in the engine room. The
tank cover must be removed for access to the screens
b. Suction Strainer Service, Hull Numbers 8500
which are attached to the suction lines ,near the bottom
thru 8519. See figure 2-8.1.
of the tank.
(1) The strainer contains a reusable twin
See figure 4-62.
element. A bypass valve opens as the element becomes
(2) Drain oil and clean the screens every 200
clogged, to allow fluid to flow without passing across the
hours.
element. A vacuum indicator shows a red sleeve to
indicate that fluid is bypassing the element. When the red
4-88. Ramp Hoist System Pumps
sleeve appears the elements must be cleaned.
a. General. Power for the ramp hoist system is
(2) Close gage valve between filter and tank.
supplied by two hydraulic pumps which are di4rect driven
(3) Place a pan below the strainer to catch the
by front power take-offs on the outboard engine of each
oil; then remove cover at bottom of strainer. Inspect seal
propulsion unit. Each -power take-off includes a manually
ring and replace if in poor condition. Clean cover
operated clutch. The system may be operated using one
thoroughly.
or both pumps; however, both pumps are needed for
(4) Carefully remove the element assembly.
maximum rated winch speed.
Avoid striking the wire cloth against edges of filter
b. Removal (fig. 4-74).
housing as wire cloth may be easily damaged.
(5) Place the element assembly, with flat end
(1) Clean hose connections at pump,
down, on a flat surface. Reach through the top and open
disconnect lines, and cap open ends.
conical end of the element sidewise, inner and outer
(2) -Remove pump coupling.
element assembly will come apart easily.
(3) Remove pump from support.
c. Installation. Install pump in reverse order of
(6) Inspect housing and clean thoroughly.
(7) Place both inner and outer elements in a
removal. Align pump with power take-off shaft before
container of clean solvent and al-low to soak 'long
tightening mounting bolts.
enough to soften accumulated contaminant. A non-
metalic bristle brush may be used to remove caked
4-89. Control Valve
contaminant.
a. General. Hull numbers 8500 thru 8519 and hull
(8) When caked dirt has been thoroughly
numbers 8520 thru 8560 and 8580 thru 8618 use similar,
removed, rinse element in clean solvent. If available, use
but not identical, control valves for the ramp hoist
air hose to blow the element clean. When cleaning outer
system. Hull numbers 8500 thru 8519 have a Vickers
element blow air from inside toward outside and when
CM2N02-jR20B-L-30 control valve which is mounted on
cleaning the inner element, blow outside inward.
the pilot house on the port side. Hull numbers 8520 thru
8.560 and 8580 thru 8618 have a Vickers CM3-N02
4-75
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